ALLIS - CHALMERS MOTOR AND GENERATOR REFERENCE BOOK

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP83-00423R001200450002-7
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 68
• Document Creation Date: November 9, 2016
• Document Release Date: March 10, 1999
• Sequence Number: 2
• Content Type: BOOK

. approved For.. Release 1999109/10 : CIA-RDP83-00423 R001200450002--7
MOTO
C 30042
.and GENERATOR
 Approved For Release 1999/09/10 : CIA-RDP83-00423R001200450002-7
ALUSCNALMEF
MOTOR
and GENERATOR
0
Approved For Release 1999/09/10 : CIA-RDP83-00423R001200450002-7
 Approved For Release 1999/09/10 : CIAO-RDP83-00423R001200450002-7
' TBook his Allis-Ch lmers Motor and Generator Reference
is r printed from the complete Electrical
Reference Bool published by the Electrical Moderni-
zation Bureau nd edited by Mr. iE. S. Lincoln. Allis-
,Chalmers sponsored this section of the book and
furnished all o the text and illustrations for the part
on integral hor iepower motors and generators.
This is not int nded to be a text book on the broad
field of motors and generators. lEt is rather a brief
outline of information that we believe will assist in
the selection o motive power to handle most indus-
trial applications.
For specific information on any of the equipment
described in th se pages we suggest that you get in
touch with th Allis-Chalmers sales office nearest
you. A comple a list is given at the end of the book.
The complete Electrical Referencebook of over 1700 pages
cover the entire field of industrial electric operations
from service entrance equipment to power distribution
and tilization. It can be obtained for $18.75 each from
The Electrical Modernization Bureau, Inc., 124 Mama-
roneck Ave., White Plains, N. Y.
Approved For Release 1999/09/10 : CIAO-RDP83-00423R001200450002-7
 Approved, For Release 1999/09/10 : CIA-RDP83-00423R00120045Qn nn.'R--77 H-1
'N[ S AND
MOTORS AND GENERATORS
INTRODUCTION
One of the most important functions of electricity
is the production of mechanical power for industrial
plants through the medium of electric motors. The
millions of horsepower provided by electric motors
have done much to make our modern standard of
living possible.
Motors, like all electrical equipment, have been
developed to the point where they provide outstand-
ing reliability and flexibility if they are properly
applied.
Basically, a motor is simply a means of producing
mechanical power from electricity through change in
the direction of a magnetic field. In ac motors, this
change is produced by the current itself, while in do
motors, the change is produced by a commutator,
which acts as a switch to maintain the proper rela-
tionship between the magnetism of the armature and
field. In other words, both ac and dc motors operate
on the principle of magnetic induction, attraction
and repulsion, and differ only in the method by which
magnetic action is applied.
This same principle and distinction also applies to
generators. Electricity can be generated commercially
only from motion produced by a prime mover.
STANDARDIZATION
The National Electrical Manufacturers Association,
in cooperation with other organizations, such as the
AIEE and ASA, has done much toward developing
standards for motors and generators. The standards
define products, processes and procedures with ref-
erence to nomenclature, composition, construction,
dimensions, tolerances, safety, performance, quality,
rating, testing, and service.
GENERATORS
CPYRGHT
While conformance to the standards is not com-
pulsory, most manufacturers generally adhere to them.
Hence the difference between products of various
manufacturers is in the means by which the applicable
standards are met. This is one of the main reasons
why manufacturers' descriptive literature emphasizes
particular features of construction as the best means
of simplifying comparison of different makes.
Standardization benefits both the manufacturer
and the purchaser. The standards are designed to
eliminate misunderstanding between the manufacturer
and purchaser and to assist the purchaser in selecting
and obtaining the product for his particular need.
Selection would be extremely difficult if every manu-
facturer proceeded on his own entirely independent
way. In addition, the standards help promote pro-
duction economies, which benefit both manufacturer
and purchaser.
MOTORS-GENERAL INFORMATION
Today, industry is more dependent than ever on
uninterrupted operation of electric motors in successive
production steps. At the same time, the motors are
subjected to increasingly severe operating conditions.
In many modern plants, processing has become an
integral part of the production line, and the electrical
equipment may have to operate successfully in the
presence of corrosive and explosive fumes, conducting
and abrasive dusts, steam, vapor, or dripping or
splashing liquids.
The insulation used on standard motors is suitable
for most applications-even where moderate amounts
of moisture, weak acids or alkalies, non-conducting
abrasive dusts, oil, and so forth are present. But
for unusually severe conditions, special insulation or
enclosing features, or both, may be needed to give
the motor a normal operating life.
Fig. H-1. Squirrel-cage induction motor rated 250-hp, Fig. H-2. Centrifugal compressor for brine-cooling
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 H-2 CPYRGHT
MOTOApproved For Release 1999/09/10 : Cl -RDP83-00 M b0450002-7
GENERAL
HORSEPOWER RA INGS
Motor mane ac ure s, under the auspic is of NEMA,
have agreed on certain rating standards based on
definite operating conditions, such as voltage, fre-
quency, speed, ambi nt temperature, etc. Standard
horsepower ratings ar4 given under the various motor
divisions which follow.
Open-type general-~urpose motors are guaranteed
to develop their ratedhorsepower continuously with-
out a temperature inc ease of more than 40 C above
a normal ambient of room temperature of 40 C.
Where enclosures are fused, motors generally operate
at higher temperatures because of ventilating re-
strictions. Such motors have temperature ratings of
50, 55, 70, or 75 C, depending upon the type of en-
closure and insulation.
Open-type general-purpose motors, when operated
at rated voltage (anc frequency in the case of ac
motors), will carry Continuously 1.15 times their
rated load without injurious temperature rise. This
is known as their service factor. (Alternating-current
motors smaller than three hp have slightly larger service
factors.) There may bq slight differences in efficiency
and power factor from those at rated load.
For maximum efficiency, a motor that will operate
as near full load as possible should be selected. In
most cases, the manufacturer of the machine to be
driven by the motor cap give the power requirements.
If definite informatio is not available, the best
method of obtaining he power requirements of a
given application is b actual test, using a spare or
rented motor.
fficiency varies with the load placed on the motor
Is usually highest when the motor is fully bade
ected by variations of voltage and frequency.
Large motors are more efficient than small motors
r the same horsepower ratings, high-speed motor
e more efficient than low-speed motors becaus
gh-speed motors have louver losses since less materia
required in their construction. Except for the large
es, high-voltage motors (2300 volts and over) ar
efficient than low-voltage motors of the sam
rigs, due to the greater space .required. for insulatin
windings.
EED CHARACTERISTICS
Except for synchronous motors, speeds of motors
ry somewhat with their loads. This variation in
ed is termed speed regulation arid is expressed in
cent of full-load speed. 'For a normal speed of 1750
a variation of 10 percent below normal would
an a loss of 175 rpm, resulting in a running speed
1575 rpm.
sect-current motor speeds depend upon the
tage of the circuit on which they operate and may
increased or decreased by varying the supply
tage. Alternating-current motor speeds, however,
end upon the frequency of the circuit and cannot
increased except by increasing the frequency of
circuit.
ynchronous speeds for different ac frequencies are
en in Table 1. These speeds apply directly to syn-
EFFICIENCY
The efficiency of a rrtotor is the ratio of its output
(or its input minus all; losses that take place in the
motor) divided by its input expressed in the same
terms.
onous motors. Induction motors operate at slightly
er speeds due to the slip which is inherent in their
de gn.
peed limitations recommended by NEMA for
me ors using belt, gear and chain drives are given
by Table 2.
rig. H-3. This centrifugal blower is driven by a Fig. H-4. These 3000 and 2500-hp direct-current
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 H-3
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GENERAL
TABLE I-SYNCHRONOUS SPEEDS-AC
GENERATORS AND MOTORS
Poles X Rpm
Frequency = 120
Number of Poles
Revolutions per Minute When Frequency Is
(Generator
or Motor)
25 Cycles
50 Cycles
60 Cycles
6
0
2
1500
3000
0
3
4
750
1500
1800
6
500
1000
1200
8
375
750
900
10
300
600
720
12
250
500
600
14
214
429
514
16
188
375
450
18
167
333
400
20
150
300
360
22
136
273
327
24
125
250
300
26
115
231
277
28
107
214
257
30
100
200
240
32
94
188
36
83
167
200
40
75
150
180
44
-
136
164
48
-
125
150
52
-
115
138
56
-
107
129
60
-
100
120
66
-
91
109
72
-
83
100
76
-
79
95
80
-
90
84
86
80
90
The pull-up torque of an ac motor is the minimum
external torque developed by the motor during the
period of acceleration from rest to the speed at
which breakdown torque occurs. For motors which
do not have a definite breakdown torque, the pull-
up torque is the minimum torque developed up to
rated speed.
The breakdown torque of an ac motor is the maxi-
mum torque which it will develop with rated voltage
applied at rated frequency, without an abrupt drop
to the horsepower times 5250 divided by the full-
load speed.
The locked-rotor (static) torque of a motor is the
minimum torque which it will develop at rest for
all angular positions of the rotor, with rated voltage
applied at rated frequency.
The full-load torque of a motor is the torque
necessary to produce its rated horsepower at full-
load speed. In pounds at one foot radius it is equal
MOTOR TORQUES
One of the principal factors in the selection of the
proper motor is the torque required by the driven
machine from starting to shutdown. Following are
the NEMA definitions of the torques that must be
considered:
TABLE 2-SPEED LIMITATIONS-BELT,
AND CHAIN DRIVES
This table, based on NEMA definitions, represents good
practice (under normal operating conditions) for the use
of these drives on motors and generators which are not
provided with outboard bearings.
Full-Load Rpm of Motor
or Generator Maximum Maximum
IIp Rating Kw Rating
Above Including of Motor of Generator
Flat-Belt Drive (1)
15
2400
3600
20
1800
2400
30
20
1200
1800
40
30
900
1200
75
50
750
900
125
75
720
750
150
100
560
720
200
50
1
V-Belt Drive (2)
15
2400
3600
0
20
40
30
1800
240
75
50
1200
1800
75
900
1200
125
750
900
200
100
720
750
250
150
560
720
300
Gear Drive (3) (4)
1500
1800
71/2
l5
1200
1500
15
25
15
900
1200
50
30
750
900
5
50
560
750
7
Chain Drive (5)
2400
3600
20
15
1800
2400
40
30
1200
1800
75
40
900
1200
125
200
125
750
900
50
250
150
720
7
200
560
720
300
See NEMA MG1-3.13 for dimensions of standard pulleys
and for limiting dimensions of pulleys.
(2) Limiting dimensions of V-belt sheaves for general-purpose
motors in frames 505 and smaller are given In NEMA
r
nsions for v-,,, s eaves
d
i
i
(3)
(4)
ime
ng
t
MGI-3.15. Lim
motors in frames larger than 505 have not been standardized;
they are specified by the motor manufacturer.
These values are based on the use of steel pinions.
In general, for quiet operation and freedom from severe
vibration, the peripheral speed of cut-steel gearing at the
pitch diameter should not exceed 1400 feet per minute. For
further information, see American Standard Gear Tolerances
and Inspection, Publication No. B6.6-1946, or latest revision
thereof.
(5) Limiting dimensions of chain-drive sprockets for general-
purpose motors in frames 505 and smaller are given in
NEMA MG1-3.14. Limiting dimensions of chain-drive
sprockets for motors in frames larger than 505 have no
been standardized; they are specified by the motor manu-
facturer.
NOTES: The above limitations are based on the use of pulleys
etc., as standardized by NEMA. The limitations will be less tha
those given when motors are belted to low-speed drives, sue
as countershafts.
The above values are not intended to establish a definit
dividing line below which the use of outboard bearings is no
the motor user what establish the manufacturers considert
indicate to but
be good practice in general service.
The use of outboard bearings is approved and recommende
for belted motors in frame sizes of 250 hp, 575 to 600 rpm an
larger.
t th
h
in speed.
The pull-out torque of a synchronous motor is the
motor will
-P R
dev r th q n i he moor.
(IN 6 1200450002-7
a
Where an outboard bearing is specified, it is assumed t
late and slide rails, if r
 H-4 CPYRGHT
MoTOApproved For Release 1999/09/10 : CI -RDP83-00423 R001200450002-7 .-
rated voltage applied at rated frequency and with
normal excitation.
The pull-in torqu}? of a synchronous motor is the
maximum constant! torque under which the motor
will pull its connect ;d inertia load into synchronism,
at rated voltage and frequency, when its field
excitation is appliegl.
The speed to which a synchronous motor will
bring its load depends on the power required to
drive it, and whethjer the motor can pull the load
into step from this peed depends on the inertia of
the revolving part, so that the pull-in torque
cannot be determind without having the Wk2 as
well as the torque of the load.
The locked-rotor toque of a motor must be well
above the torque requir red to start the driven machine
from rest. This may be anywhere from 10 to 250
percent of full-load torque, depending upon the type
of driven machine. Low voltage and the type of starter
employed affect the locked-rotor torque of the motor.
The torque delivered by the motor (after breakaway)
for acceleration to fu4 speed must also be well in
excess of the torque required by the driven machine.
The greater this margin, the shorter will be the time
equired to accelerate the inertia (Wka) of the rotating
arts of the driven m' chine (and the rr..otor rotor)
to full speed. In otherjwords, the time required for
cceleration is a function of the torque available for
his purpose and the ' Vk2. (Note also the effect of
oad inertia on pull-in torque of synchronous motors
5 discussed under thIe NEMA definition above.)
To prevent the inotoi from stalling, the breakdown
r pull-out torque
(see NEMA definitions above)
ust be greater than the maximum torque required
INSULATION AND 1EMPERATURE LIMITS
Operating temperatures have a very pronounced
cffect on the operating! life of motors because the
t mperature, to a largq extent, determincas the life
the insulation. The !type of insulation, in turn,
determines the maximum temperature allowable for
reasonable motor life.
NEMA has defined several classes of insulation for
c nsideration in connection with temperature limits.
he two most commonly Ised on motors and generators
are:
Class A: (1) Cotten, silk, paper and similar
organic materials when either impregnated or
immersed in a liquid ! dielectric; (2) molded and
laminated materials with cellulose filler, phenolic
Class B: Mica, asbestos, fiber glass and similar
inorganic materials in. built-up form with organic
binding substances. A small portion of Class A
material may be used for structural purposes only.
The highest observable temperatures permissible
r open machines, based on AIEE standards. a.ra
easured by- Class A Insulation Class B Insulation
sistance............ 100 C +y~
A_,__, ,_. 120C
1.
-
The limiting observable temperature for totally-
.closed machines is 5 C higher than for open machines.
It should be noted that while a standard motor can
operated at the above temperatures without sacri-
ing the life expectancy of the insulation, the rating
d other operating characteristics may be based on
ne other temperature. For example, open general-
rpose ratings, which have Class A insulation, are
ed 40 C rise based on a 40 C ambient temperature-
it is, a total temperature of 80 C (by thermometer);
this case, the additional permissible 10 C permits
ervice factor, as discussed earlier under the heading
rsepower Ratings.
(rdinarily, Class A insulation is standard. Class B
ulation, which is more expensive, is used principally
permit higher operating temperatures but also
>rds some other advantages in high-voltage ma-
zes. Some machines lend themselves to a combina-
i of the two classes of insulation. In some cases,
additional cost of Class B insulation may be
nterbalanced by the fact that it may permit the
of a smaller frame size for a given rating. Inter-
tent operation or adverse ambient conditions may
ire specially treated insulation.
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to
affc
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the
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are
and
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such
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with
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esins and other resins of similar properties; (3) Ope
lms and sheets of dellulose acetate and other A
cellulose derivatives ofd similar properties; and (4) whit
arnishes (enamel) as lie t pgc
Amroved 'fir Re?I6 &X9/09/10: .
CHANICAL PROTECTION AND
rHOD OF COOLING
he mechanical protection. features covered by the
wing definitions (NEMA unless otherwise noted)
n general available in and applicable to most ac
do motors and generators. There are of course
ptions. For example, the totally-enclosed non-
Hated type is limited to a few horsepower, after
h the fan-cooled type takes over. Likewise, a
ly-enclosed machine may be enclosed with air
ors and use a recirculating ventilating system, but
construction is generally confined to large high-
1 machines having a specific rating over 1 hp
va) per rpm. The internal construction of motors
various degrees of enclosure is basically the same
at of open machines.
Machines
open machine is one having ventilating openings
permit the passage of external cooling air over
"R8 30?4 3ROO112204 02.7
 CPYRGHT
Approved For Release 1999/09/10 : CIA-RDP83-00423 R001200450002-7 H-5
MOTORS
Fig. H-5. Sectional view of typical drip-proof,
general-purpose, squirrel-cage induction motor.
Fig. H-6. Typical construction for drip-proof,
general-purpose, squirrel-cage induction motors.
Fig. H-7. Drip-proof construction of large motors
is illustrated by this 300-hp, 695-rpm machine.
Fig. H-8. Sectional view of splash-proof 'squirrel-
cage motor in general-purpose rating range.
Fig. H-9. Splash-proof construction typical of
that used in the general-purpose rating range.
Fig. H-10. Two-pole cage motors, such as this
2000-hp unit, frequently must be splash-proof.
A drip-proof machine is an open machine in which A splash-proof machine is an open machine in which
the ventilating openings are so constructed that drops the ventilating openings are so constructed that drops
of liquid or solid particles falling on the machine at of liquid or solid particles falling on the machine or
any angle not greater than 15 degrees from the vertical coming towards it in a straight line at any angle not
cannot enter the machine either directly or by striking greater than 100 degrees from the vertical cannot
and running along a horizontal or inwardly inclined enter the machine either directly or by striking and
surface. WfrplbOea&Fx r Release 1999/09/10 : Ct R83g0 2&R0(V32GQ45O02. d 12.)
 H-6 Approved For Release 1999/09/10 : Cl
MOTORS
GENERAL
Fig. H-11. Large, 'splash-proof motor of the
pedestal-bearing type.
Fig. H-12. Splash-proof construction is also
available in vertical motors.
RDP83-00423M4$0002-7
Fig H-14. This dc motor Is semi-protected since it
ha expanded-metal covers over top half openings.
Fi!. H-15. Expanded-metal covers on both top and
bo torn openings make this a protected dc motor.
Fil. H-16. Drip-proof protected dc motors have solid
and expanded-metal covers, as shown above.
semi-protected machine is an open machine in
w ich part of the ventilating openings in the machine,
us ally in the top half, are protected as in the case of
a "protected machine" but the others are left open.
Fig. H-13. Large otherrsquirrel-cage A protected machine is an open machine in which
A rAiW(~o~Qn6tlea ee1999/09/10 : C1 RtDM"~1aRo9f }bP45OO6r2a7d shape.
 -7
MOTORS
GENERAL
- ----?--?-- --? - ----- -CRAIGN.T-------- H-7
Such openings shall not exceed 1/2 square inch (323
square millimeters) in area and are of such shape as
not to permit the passage of a rod larger than 1/2 inch
(12.7 millimeters) in diameter except where the dis-
tance of exposed live parts from the guard is more
than 4 inches (101.7 millimeters), the openings may
be 3/4 square inch (484 square millimeters) in area
and must be of such shape as not to permit the passage
of a rod larger than 3/4 inch (19 millimeters) in
diameter. (Fig. 15.)
A drip-proof fully protected machine is a drip-proof
machine whose ventilating openings are protected
in accordance with the preceding paragraph. (Fig. 16.)
Fig. H-18. Tube-type, totally-enclosed, fan-cooled,
wound-rotor motors installed outdoors.
Note 2: Chicago covers consist of hinged perforated
covers for all openings on the collector end of wound-
rotor motors or the commutator end of de machines.
Fig. H-17. Installation view of open, externally
ventilated dc motor with frame-mounted blower.
An open externally-ventilated machine is one which
is ventilated by means of a separate motor-driven
blower mounted on the machine enclosure. Mechanical
protection may be as defined in the preceding para-
graphs. (Fig. 17.)
An open pipe-ventilated machine is an open machine
except that openings for the admission of the venti-
lating air are so arranged that inlet ducts or pipes
can be connected to them. This air may be circulated
by means integral with the machine or by means
external to and not a part of the machine. In the
latter case, this machine is sometimes known as a
separately or forced-ventilated machine. Enclosures
may be as defined in preceding paragraphs.
A weather-protected motor is an open motor (protected
in accordance with that definition above) whose
ventilating passages are so designed as to minimize
the entrance of rain, snow and air-borne particles
to the electrical parts.
Note 1: ASA C-42 definition is: An open machine
is a self-ventilated machine having no restriction
to ventilation other than that necessitated by me-
chanical construction. Thus, in the sense of this
definition an open machine, when the term is used
without qualification, is understood not to include
Totally-Enclosed Machines
A totally-enclosed machine is one so enclosed as to
prevent exchange of air between the inside and the
outside of the case but not sufficiently enclosed to be
termed air-tight.
A totally-enclosed non-ventilated machine is a totally-
enclosed machine which is not equipped for cooling
by means external to the enclosing parts. (Fig. 20.)
A totally-enclosed fan-cooled machine is a totally-
enclosed machine equipped for exterior cooling by
means of a fan or fans integral with the machine but
Fig. H-19. Outdoor installation of vertical, tube-
the lisA}Dp>> deForaReIease 1999/09/10: CIA-RDPOmID&49MO(I T l$SoW2p'Ptors.
 H-8 Approved or Release 1999/09/10 : Cl
MOTORS
GENERAL
external to the enclosing parts. (Figs. 18, 19 and 30
show fan-cooled motor's in service. See also Figs. 21, 22
and 2s.)
An explosion-proof; machine is a totally-enclosed
machine whose enclo 'ure is designed and constructed
to withstand an explosion of a specified gas or vapor
which may occur within it and to prevent the ignition
of the specified gas orb vapor surrounding the machine
by sparks, flashes or explosions of the specified gas
or vapor which may occur within the machine casing.
(Figs. 24, 25 and 31 show typical explosion-proof
motors.)
Note: See page 10 for classification of hazards.
Fig. H-20. Totally-enclosed non-ventilated design is
limited to small motors-usually 2-hp or less.
Fig. H-21. Totally-enclosed fan-cooled construction
used for general-purpose ratings is shown above.
RDP83-00423 R001200450002-7
Fig. H-23. Sectional view through typical general-
purpose, totally-enclosed, fan-cooled cage motor.
Fij. H-24. Explosion-proof construction is modifica-
tion of totally-enclosed fan-cooled design.
Fi~. H-25. Tube-type cooling makes large totally-
enclosed explosion-piroof motors practical.
dust-explosion-proof machine is a totally-enclosed
machine whose enclosure is designed and constructed
so as not to cause the ignition or explosion of an am-
bient atmosphere of the specific dust, and also not to
case the ignition of the dust on or around the machine.
Vote 1: Successful operation of this type of machine
equires avoidance of overheating from such causes
excessive overloads
stalling
or accumulation of
,
,
Fig. H-22. Large TEFC motors need special cooling xcessive quantities of dust on the machine.
designs, such as the tube-type air-to-air heat exchanger Ap veidn "dR l as&4999/09110 : CI DP83*Q422&OdiA2Q,45OMJrds.
CPYRGHT
 Approved For Release 1999/09/10 : CIA-RDP83-00423 R001200450002-7 u
r,
A water-proof machine is a totally-enclosed machine
so constructed that it will exclude water applied in
the form of a stream from a hose, except that leakage
may occur around the shaft, provided it is prevented
from entering the oil reservoir and provision is made
for automatically draining the machine. The means
for automatic draining may be a check valve or a
tapped hole at the lowest part of the frame which will
serve for application of a drain pipe.
Note: A common form of test for a water-proof
machine is to play on the machine a stream of water
from a hose with a one-inch nozzle delivering at
least 65 gpm from a distance of about 10 feet, from
any direction, and for a period of not less than 5
minutes.
A totally-enclosed pipe-ventilated machine is a totally-
enclosed machine except for openings so arranged that
inlet and outlet ducts or pipes may be connected to
them for admission and discharge of the ventilating
air. This air may be circulated by means integral with
the machine or by means external to and not a part
of the machine. In the latter case, these machines
shall be known as separately or forced-ventilated
machines. (Fig. 26.)
Note: ASA definition of an enclosed, separately
ventilated machine is a machine having openings
for the admission and discharge of the ventilating
air, which is circulated by means external to and
not part of the machine, the machine being other-
wise totally enclosed. These openings are so ar-
ranged that inlet and outlet duct pipes may be
connected to them.
SERVICE CONDITIONS
General-purpose 40 C motors are designed to give
successful operation at rated load under the following
MOTORS
GENERAL
Fig.'. H-27. Base ventilated motor with air intakes
and discharge at the bottom of the stator yoke.
Fig. H-28. Completely assembled cage motor using
recirculating ventilating system with air cooler.
service conditions defined by NEMA as usual:
1. An ambient temperature not exceeding 40 C.
2. A variation in voltage of not more than 10
percent above or below the nameplate rating.
3. A variation in frequency of not more than 5
percent above or below the nameplate rating.
4. A combined variation of voltage and frequency
of not more than 10 er t b
c
p
en a ove or below
Fig. H-26. Pipe-ventilated motor with top air the nameplate ratin rii f e
r uency
intakeAp I &de R LdbgEOq98?/09/10: CIA-lad ' 4$e 3F~y e i~'do. LL
 C-PYRGHT
H-10 Approved For Release 1999/09/10 : CI -RDP83-00423R001200450002-7
MOTORS
ii6MERA L
Fig. H-29. Splash-proof 75-hp cage motors were
selected for chemicpl processing plant drive.
5. An altitude notj exceeding 3300 feet (1000
vent agents harmful to the insulation or to
meters). Location or atmospheric conditions as to dust,
current-collecting parts, the use of enclosed
moisture or furies which will not seriously
or separately ventilated motors may be necessary.
interfere with the ventilation of the motor.
Exposure to conducting or abrasive dusts, such
Solid mounting and all belt and chain drives
as coal, coke, carbon, graphite, iron, etc. Even
and gearing in accordance with adopted
in small amounts these may be extremely
standards.
harmful to insulation, and the use of enclosed
In general, since the service conditions to which such
motors is preferable.: Open motors with special
motors are subjected are uncontrolled and not subject
insulation may suffice for lower voltages.
A combination of conductive or abrasive dusts
to exact determination) I i the basis of rating chosen, in
standards, provides a factor
accordance with NEM plus sulphur fumes and moisture is often en-
mperature rise at 100 percent
of safety of 10 C in t countered in power plant boiler rooms around
d coal-pulverising equipment.
loading.
Specific service con itions defined by NEMA as ash-handling and
Exposure to hazardous atmospheres containing
service conditions more favorable than usual are:
flammable or explosive gases or combustible or
1. Operation at rated voltage and frequency.
explosive dusts requires totally-enclosed explo-
2. Individual application to a machine where the
sion-proof motors.
loads and duty cycle are accurately known and
The National Electrical Code designates haz-
cannot be exceeded.
ardous gas locations as Class I and hazardous
dust-and-air locations as Class II. Class I is
Unusual Service Conditions
divided into Groups A, B, C, and D, Group A
Where apparatus into be subject to any one or a
being the most hazardous and Group D being
combination of the following conditions, the manu-
the least hazardous. Similarly, Class II is
facturer should be consulted to make sure that the
divided into Groups E, F, and G, Group E being
proper motor is selected :
the most hazardous and Group G being the
1. Exposure to st4am or excessive moisture from
least hazardous. Motors for Class I Groups A
other causes, such as vapor or excessive splashing
and B are generallx not available.
and dripping, as may be encountered in parts
6. Exposure to lint, such as encountered by tex-
tile mill motors, may quickly clog ventilating
of dye houseq . , bleacheries, packing plants, paper mills, metal mines, etc. These conditions
of open motors and make totally-
may require special insulation, low-voltage passages
enclosed motors desirable for looms, and special
designs, and/or enclosed motors.
self-cleaning motors for spinning frames, etc.
2. Exposure to tl e corrosive action of salt-laden
Exposure to abnormal shock or vibration may
necessary.
air usually requires special consideration of 7. 1 insulation and the use of non-corroding nuts,
make special structural materials
Exposure to ambient temperatures above 40 C
bolts and currnt-collecting parts. S
(104 F). Where the windings will be subjected
fi v es or 1` o nts TAW, r9 1 CI -RD -Q04 04x11 * tempera-
H-30. Dust in lime plant dictated selection of
this 71/2-hp, totally-enclosed fan-cooled motor.
ical, fertilizer and similar plants. Where the
ambient atmosphere contains corrosive or sol-
fwb~
 Approved For Release 1999/09/10 : CIA-RDP83-00422386 d(T450002-MOTOWlt
RS
GENERAL
Fig. H-31. Explosion-proof, totally-enclosed fan-
cooled motors were needed for oil pipe-line station.
ture plus operating temperature. rise) above 90 C
for open motors, or 95 C for enclosed motors,
Class B insulation is required. Maximums for
Class B are 110 and 115 C respectively.
Outdoor operation requires a degree of enclosure
dependent on the climate involved. Usually
totally-enclosed types are preferable. Splash-
proof construction should be limited to the milder
climates and lower voltages. Low ambient
temperatures require special consideration of the
bearing lubrication. In general, outdoor in-
stallations are not recommended under condi-
tions of extreme cold and heavy snows.
Operation in poorly ventilated rooms or pits
is undesirable. If such locations are unavoidable,
means should be provided for separate forced
ventilation to insure an ample volume of cooling
air.
TABLE 3-COMPARISON OF DC AND AC MOTORS
Speed
adjustment
Direct Current Alternating Current
Limited to 230 Any standard volt-
volts on ordinary age available with
circuits. use of transformers.
Good.
Unsatisfactory and
heavy current-
except wound-
rotor motors.
Efficiency High.
Intermittent Good.
starting service
Starting Generally low. High for cage type.
currents
Maintenance Higher because of Low.
commutator.
Constant speed
Semi-constant
speed
Speed adjustable
but remaining
constant
Shunt motor with In combination with
field control. magnetic coup-
lings.
Fig. H-32. Special textile motors are available for
applications like these cotton spinning frames.
SELECTING A MOTOR
There are many factors to be considered in selecting
the right type of electric motor for a specific drive.
First, the requirements of the machine to be driven
must be considered. This involves not only establishing
the motor size (which may be a problem in itself) but
also consideration of other characteristics of the load
which have a direct bearing on the type of motor to be
selected. What is the required operating speed? Should
it be constant, adjustable or variable? What are the
torque requirements? These and many other factors
must be considered if an intelligent selection is to be
made.
Second, there are questions of power supply. What
current is available-direct or alternating? Should
plant power factor be improved? Are there power
company current limitations?
Third, ambient conditions must be considered. Will
the motor need special protective enclosures? Special
insulation? Separate ventilating equipment?
Fourth, the available forms of motors must be
weighed in relation to the characteristics desired, and
the economics of initial and future costs must be
investigated.
Take a compressor for example. If initial cost is the
main consideration and plant power factor can be
ignored, a squirrel-cage induction motor is the obvious
choice for small and medium sized compressors. For
heavy-duty compressors requiring large motors, the
smooth acceleration and low starting current of wound-
rotor motors justifies their use. But if there are already
numerous induction motors in the plant, the best
choice may be a synchronous motor to provide cor-
rective kva for plant power factor improvement.
Tables 3 and 4 are provided as a general guide for
use in selecting motors. Whenever there is any question
about an application, the motor manufacturer should
be furnished with as complete information as possible.
Failure to do so might result in misapplication. Table 5
Speed varying Series motor. Wound-rotor motor formation
with Approved For Re lease 19991*09 91: C lP 8 !O At2 ? O 4V66b? -'
 H-12
CPYRGHT
MOTORSApproved For Release 1999/09/10 : CIAO-RDP83-00423R001200450002-7 .
GENERAL
Fig. H-33. Sectional view through ring-ailed sleeve
bearing used on large end-shield bearing motor.
APPLICATION
Agitator
Baler (power)
Ball mill
Blower (positive pressure):
Boring mill
Buffer
Cement kiln
Compressor
Conveyor
Crane
Crusher
Dough mixer
Drilling machine
Drying tumbler
Elevator
Fan (centrifugal
Finishing stand
Grinder
and propeller)
Hammer (power)
Hammer mill
Hoist
Jordan
Keyseater
Lathe
Laundry extractor
Laundry washer
Line shaft
Metal grinder
Metal saw
Milling machine
Mill table
Mine hoist
Molder
Ore grinder
TABLE 4-MOTOR
MOTOR ;SYMBOL
Alternating Direct
Current Current
lA-1B-2B 6A
1D 6B-7
1C-2B-3A 611
lA-1B-2B-3A-4 6A
2A-3A 6A-8
IA-1B-2A 6A
3A 8
IA-1B-1C-3A-.4 6B-8
IA-IC-2B-3A 6B-8
1D-2A-3B 7
1A-1C-1D 6A-6B
IA-1B-1C-2B 6A-6B
IA-1B-2A 6A-8
IA-lB-1.D 6A
1D-1E-2B-3B 611-8
lA-1B-2C-3A.4 6A-8
3B 8
IA-1B-2A 6A
1D 6B
1C 6A
1D-2A-3B 7
IA-1B-4 6A
IA-1B 6A
IA-1B-2A 6A-8
1C-1D 6B
IA-1B-1D 6A
lA-lB 6A
IA-1B 6A
IA-1B 6A
IA-1B-2A 6A-8
3A 8
3B 8
IA-1B 6A
Pipe threader IA-1B
Planer IA-1B 6A
Polisher 1A-1B-2A 6A
Printing press (job) IA-1B-3A 6B-8
Printing press (rotary and offset) 3A 611-8
Pulverizer 1C 611
Pump (centrifugal) 1A-1B-211-3A-4 6B
Pump ppred For 6 as 19"/09/10
Fii. H-34. Partially dismantled capsule-type sleeve
earing of same type as that shown in Fig. H-33.
MOTOR SYMBOL
Roo
PPLICATION
k crusher
Alternating
Current
3A
Direct
Current
6B-7
Sat
der
IA-1B
6B
Sat
d mixer (centrifugal)
1C
6A
Sa
(circular)
1A-1B
6A
Saw
(band)
IA-1B-.1C-3A
6A-6B
Ser
w machine
IA-1B
6A
She
per
IA-1B
6A
Spi
m
nning and weaving
achinery
IA-1B
6A
Sto
er
IA-1B-1C-2B
6A-8
Tu
bling barrel
1C
6A
Wit
ch
1D-3A
6B-8
EXPLANATION OF SYMBOLS
1. uirrel-Cage, Constant-Speed
Normal torque, normal starting current
I. Normal torque, low starting current
. High torque, low starting current
D. High torque, high slip
Elevator
2. S uirrel-Cage, Multi-Speed
. Constant horsepower
Constant torque
Variable torque
Note: Classes "A," "B" and "C" listed under "1" are
a so applicable to multi-speed motors. The listing ("A,"
" "or "C") for the constant-speed motor indicates the
firm of motor to use under "2." For example: If the
Ii ting shows 1C-2B, then the multi-speed, constant
torque motor should also be high torque, low starting
current.
3. 'Wound-Rotor
A General-purpose
B Crane and hoist
4. Synchronous
6. D rect-Current, Constant-Speed
A-Shunt-wound -
B Compound-wound
7. D rect-Current, Variable-Speed, Series-Wound
N te: Series motors must be connected directly to the
to d (not belted).
X0660*1?0450002-7
 H.13
Approved For Release 1999/09/10 : CIA-RDP8t-ng01200450002-WOTORS
Fig. H-35. Various types of ball bearings are used
on motors. Above unit is a double-shielded type.
required for various types of motors. To this the
purchaser should, of course, add any other desired
characteristics and features and indications of any
unusual operating conditions.
MOTOR BEARINGS
Bearing design, including provision for lubrication
and protection, forms one of the most vital features
of motor construction. Bearings are one of the few
wearing parts in electric motors; in cage motors they
are, in fact, the only element that can be considered
as a wearing part.
NEW,
In properly designed sleeve bearings, the shaft
rotates on a film of oil, which prevents actual contact
between the shaft and the bearing during operation.
With clean oil, free from abrasive materials, sleeve
bearings should provide long years of service, and
they are very quiet in operation. They do, however,
normally require more attention than the anti-friction
type. Figs. 33 and 34 show typical sleeve bearing
mountings.
The use of anti-friction bearings is usually confined
to ratings in the general-purpose classification (200
hp and less). The type most commonly used is the
ball bA roved For Release 1999/09/10 : Cl fl 3nGO423R0O12O0450002-7'.""'"'
grease-lubricated ball bearing, Figs. 35 and 36, which
requires little attention except for checking grease
about once a year. Most ball-bearing troubles in the
smaller machines are, in fact, due to overgreasing.
Experience indicates that for ratings of 250 hp and
larger, particularly for speeds above 1000 rpm, anti-
friction bearings are not as reliable as oil-lubricated
sleeve bearings. For lower speeds, anti-friction bearings
are usually satisfactory in ratings up to 1 hp per rpm.
The balls, or rollers, undergo cyclical compression and
release with every revolution, so that high speeds
and high loading cause fatigue and ultimate failure.
Exceptional cases may permit the use of oil-lubricated
Fig. H-36. Cutaway view showing shielded ball
bearing installed in a general-purpose cage motor.
TABLE 5-INFORMATION REQUIRED FOR
SELECTING MOTORS
GENERAL
Type of motor (cage, wound-rotor, synchronous, or de) ........
Quantity ........ lip ........ Rpm ........ Phase ........
Cycles ........ Voltage ........
Time rating (continuous, short-time, intermittent) ............
Overload (if any)...... % for ........ Service factor........ %
Ambient temperature........ C Temperature rise.......... C
Class of insulation: Armature.. Field.. Rotor of w-r motor...
Horizontal or vertical .......... Plugging duty............
Full- or reduced-voltage or part-winding starting (ac) ........
If reduced voltage-by autotransformer or reactor......... .
Locked-rotor starting current limitations ...................
Special characteristics .....................................
INDUCTION MOTORS
Locked-rotor torque.......... % Breakdown torque........ %
or for general-purpose cage motor: NEMA Design (A, B, C, D)
....................................
SYNCHRONOUS MOTORS
Power factor.... Torques: Locked-rotor.... % Pull-in.... %
Pull-out.... % Excitation...... volts dc. Typo of exciter..... .
If m-g exciter set, what are motor characteristics?..........
Motor field rheostat........ Motor field discharge resistor.... .
DIRECT-CURRENT MOTORS
Shunt, stabilized shunt, compound, or series wound..........
Speed range ........ Non-reversing or reversing ..............
Continuous or tapered-rated ...............................
MECHANICAL FEATURES
Protection or enclosure............ Stator shift............
Number of bearings .......... Type of bearings............
Shaft extension: Flanged ...... Standard or special length .....
Press on half-coupling ........ Terminal box ................
NEMA C or D flange... ' * . . Round-frame or with feet . ..... .
Vertical: External thrust load.... lbs. Type of thrust bearing... .
Base ring type ............ Sole plates ..................
Accessories ..............................................
Load Data
Type of load ..............................................
If compressor drive, give NEMA application number ..........
Direct-connected, geared, chain, V-belt, or flat-belt drive .......
Wk2 (inertia) for high inertia drives ..................lb-ft2
Starting with full load, or unloaded ........................
If unloaded, by what means? ............................
For variable-speed or multi-speed drives, is load variable torque,
 H-14
INDUCT roved For Release 1999/09/10 : CI -RDP83-00423R0012004506YGHT
AAMnic
INDUCTION MOTORS
Applicable to a broad range of applications, induction
motors are the most; widely used because of their
simple construction. As is true of practically every
type of polyphase motor, the operation of an induction
motor depends on the production of a revolving mag-
netic field in the stator: the rotor of the machine being
pulled around by the ;revolving magnetic field.
This revolving field is produced by increasing and
decreasing currents in the stator winding. In a two-
phase motor, the magnetic field, at a given instant, is
produced entirely by the first phase winding. As the
instantaneous current decreases in the first phase and
increases in the second; a slight shift of the magnetic
field takes place. This shift continues to the point
where the second phase is producing the entire mag-
netic field.
In a three-phase motor, the third-phase winding has
a maximum field which is still further shifted around
the stator. The windings are so distributed as to allow
uniform continuous shifting or rotation of the magnetic
field around the stator;
Beyond this, induction motors operate on the prin-
ciple of magnetic indiction; that is, the magnetic
field in the rotor is induced by the current flow in the
stator. The rotor maybe (1) the squirrel-cage type,
or (2) the wound-roto? type with the ends of the
winding brought out through collector rings to an
external circuit.
SQUIRREL-CAGE POLYPHASE
INDUCTION MOTORS
Squirrel-cage motors, Figs. 5 to 10, the most common-
ly used type of polyphase induction motor, derive their
name from the similarity of their rotor windings to
squirrel cages. Since thee motors operate by induction,
the stator is sometimes' called the primary because it
receives power from th~ line, and the rotor, the sec-
ondary because its curr~nts result from the action of
the primary currents.
Fig. H-37. Wound stator for small general-purpose, defi
A'fE~IifUfp@~'It? 1999/09/10 :,
. H-38. Stator yoke and core for large cage
motor readyiFor winding.
he operation of a cage motor can best be explained
by starting with the motor at rest. When current is
supplied to the stator (primary) winding, a revolving
magnetic field is set up as described above. This
re olving field cuts the rotor conductors (cage bars)
an thereby induces voltages in the bars.
s a result of the induced voltages, current flows in
th cage winding. The current loops through the bars
an short-circuiting end rings are distributed in such
a manner as to create a magnetic field similar to that
of he stator. Interaction of these two magnetic fields
res Its in a force that tends to pull the rotor along
wi 1 the revolving field of the stator. The motor
the efore starts and gains speed.
he rotor cannot, however, rotate as rapidly as the
rev lving field of the stator. If it did, the cage bars,
instead of being cut by the revolving field, would
bee me magnetically stationary with respect to the
revolving field. In that case, no voltage would be
induced in the rotor, and there would be no attraction
between the rotor and the rotating field in the stator.
1: 1 other words, the rotor constantly slips back and an
induction motor cannot operate at synchronous speed.
Obviously increasing the load will increase the slip,
an the motor will run slower. However, at full load,
the slip is small, and motors of this type are usually
considered to be of constant speed.
Cage Motor Construction Features
e basic simplicity of cage motors is favorable to
ope ational reliability, but, careful engineering and
quality construction are nevertheless essential to
reliability and minimum maintenance.
Te stator construction (Figs. 37, 38, 39) is the same
for age, wound-rotor and synchronous motors. It com-
pris s a supporting yoke, a slotted laminated sheet-
Stec core, and insulated coils connected to provide
ite polar areas providing the revolving magnetic
-RDP83-00423R001200450002-7
 CPYRGHT H-15
Approved For Release 1999/09/10 : CIA-RDP83-00423 R0012004500gAb~CT1ON
MOTORS
6011,
Fig. H-39. Wound stator for large, end-shield
bearing, squirrel-cage induction motor.
A cage motor rotor (Figs. 40, 41, 42) consists of a
shaft, core, and cage winding. The core is built up of
slotted laminated-steel punchings mounted directly on
the shaft or supported by a spider mounted on the shaft
(Fig. 43). The winding consists of bars short-circuited
by end rings. In smaller motors, the winding is fre-
quently cast in one operation, and aluminum is often
used for this purpose. In larger motors, heavy copper
bars or rods are used, and these are brazed or otherwise
fastened to the end rings. Due to the very low voltage
in the bars, insulation is not necessary between the
bars and the rotor core.
End-shield or bracket bearing construction is used
for most cage motors. Pedestal bearing construction
is, however, commonly used for ratings above one hp
per rpm. Ball bearings are generally confined to
general-purpose sizes; sleeve bearings are available
for both general-purpose and large motors.
Fig. H-40. Squirrel-cage rotor construction typical
of ratings beyond general-purpose sizes.
Shaft rigidity and bearing quality are especially
important in these motors because, to obtain good
efficiency and power factor, the air gap between rotor
and stator must be small. It should be noted, however,
that too small an air gap can be detrimental to con-
struction, to sound level, and, by producing parasitic
torques, to efficiency.
Cage Motor Characteristics
Polyphase squirrel-cage induction motors are the
most reliable and, with the exception of large syn-
chronous motors, the most efficient motors available.
This presupposes that the motor selected for any
definite load is of such size that it can be operated at
nearly full load because the power factor and efficiency
Fig. H-43. Rotor spider and core assemblies for
Fig. /If3~rO~e R l' R~N~+HS ih99941?9~PO : C IA-RDP T)VOTI9O1MV4*3JN!2!T
 H-16 AVroved For Release 1999/09/10: Cl -RDP83-00423gpQ1gp450002-7
INDUCTI
MOTORS
also important to remember
that high-speed motors have higher power factors
than lower speed machines.
Under normal load And voltage conditions, squirrel-
cage motor speeds are practically constant and, like
those of synchronous-motors, are dependent on the
number of poles and the frequency of the power supply.
But, as previously notod, the cage motor slows down
sufficiently to produce 'the necessary torque when load
is applied. This slip is 4xpressed as a percentage of the
synchronous speed. For example, if a motor with a
synchronous speed of ;1200 rpm is loaded until the
speed drops to 1164 rpm, the slip is:
1200 - 1164 36 = 3%
1200 1: 1200
A definite relationship exists between the slip and
the efficiency of the motor; that is, the higher the slip,
the lower the efficiency, for slip is a measure of the
losses in the rotor winding. In the above example,
about 3 percent of the total power input would be
lost in the rotor winding. However, relatively high
slip motors may be necessary if high starting (locked-
rotor) torque is required by the application.
To provide the best gtarting torque consistent with
high power factor and efficiency, cage motors must be
of well-balanced design}. Within limits, the amount
of starting torque developed will depend on the re-
sistance of the rotor winding. Increasing the rotor
resistance will increase; the starting torque-with a
corresponding increase in slip and decrease in efficiency.
NEMA Design Classifications
To simplify the selection of motors by providing
some uniformity of design, NEMA has divided poly-
phase squirrel-cage motors into classes based on
electrical characteristics!. While these classifications
TABLE 7-BREAKDOWN TORQUE
T e break-down torque of Design B and C cage motors, wit
rated voltage and frequency applied, shall be in accordance wit
th following values which are: expressed in percent of full-loa
to que and which represent the upper limit of the range o
ap lication for these motors.
Synchronous Speed in Rpm
Hp (60 and 50 Cycles)
1/2 900-750
]Design
B
250
Design
C
...
Lower than 750
200
...
3/4 1200-1000
275
...
900-750
250
...
Lower than'750
200
...
1 1800-1500
300
,..
1200-1000
275
...
900-750
250
...
Lower than: 750
200
...
1-1/2 3600-3000
275
...
1800-1500
300
1200-1000
275
...
900-750
250
...
Lower than 750
200
...
2 3600-3000
250
...
1800-1500
275
...
1200-1000
250
...
900-750
225
...
Lower than 750
200
...
3 3600-3000
250
1800-1500
275
1200-1000
250
225
900-750
225
200
Lower than 750
200
...
3600-3000
225
1800-1500
225
200
1200-1000
225
200
900-750
225
200
Lower than 750
200
...
1-1/2 3600-3000
215
1800-1500
215
190
1200-1000
215
190
900-750
::15
190
Lower than 7:50
200
0 3600-3000
200
1800-1500
200
190
1200-1000
200
190
900-750
200
190
Lower than 750
200
5-25 All Speeds
200
190
30 a
d Larger All Speeds
200
190
D
sign A values are in excess Of those for Design B.
D
sign D motors have no sharply defined breakdown torque
TABLE 6-LOCKED-ROTOR TORQUE
The locked-rotor torque of Design A, B and C motors, with rated voltage and frequency applied, shall be in accordance with?the
following values, which are expressed in percentage of full-load torque and represent the upper limit of the range of application. -
60 Cy 3600 1800 1200 -DE900 N A and B
Hp 50 Cy 3000 1500 1000 750 600
Poles 2 ! 4 6 8 10
1/2 ... ... 150 150
3/4
175 150 150
1 275 175 150 150
1-1/2 175 265 175 150 150
2 175; 250 175 150 145
3 175; 250 175 150 135
5 150; 185 160 130 130
7-1/2 150 175 150 125 120
10 150: 175 150 125 120
15 150; 165 140 125 120
20 150; 150 135 125 120
25 150; 150 135 125 120
30 150; 150 135 125 120
40 1351 150 135 125 120
50 125 150 135 125 120
60 125; 150 135 125 120
75 1101 150 135 125 120
100 1101 125 :125 125 120
125 100' 110 :125 125 120
150 100' 110 125 125 120
200
100 100 ]125
2 20
The locke
-DESIGN C
600
514
450
1800
1200
900
500
428
375
1500
1000
750
12
14
16
4
6
8
115
110
105
...
...
...
115
110
105
...
...
..
115
110
105
...
...
..
115
110
105
...
...
...
115
110
105
...
...
...
115
110
105
250
225
115
110
105
250
250
225
115
110
105
250
225
200
115
110
105
250
225
200
115
110
105
225
200
200
115
110
105
200
200
200
115
110
105
200
200
200
115
110
105
200
200
200
115
110
105
200
200
200
115
110
105
200
200
200
115
110
105
200
200
200
115
110
105
200
200
200
115
110
105
200
200
200
115
110
105
200
200
200
115
110
105.
200
200
200
1
0
00
knP8
 Approved For Release 1999/09/10 : CIA-RDP83-00423F&110002-7 H-17
INDUCTION
MOTORS
TABLE 8-LOCKED-ROTOR CURRENT
Locked-rotor current measured with rated voltage and fre-
quency, shall not excee 1 the following values for 220-volt Design
B (and C and D 60 cycle) cage motors.
Hp
60 Cy
50 Cy
1/2
12
14
3/4
18
21
1
24
28
1-1/2
35
40
2
45
50
3
60
70
5
90
105
7-1/2
120
140
10
150
175
15
220
255
20
290
335
25
365
420
30
435
500
40
580
670
50
725
835
60
870
1000
75
1085
1250
100
1450
1670
125
1815
2090
150
2170
2495
200
2900
3335
Locked-rotor current at other voltages is inversely propor-
tional to the voltage.
TABLE 9A-STANDARD HORSEPOWER RATINGS
-INDUCTION MOTORS
GENERAL-PURPOSE MOTORS: 1/2, 3/4, 1, 1-1/2, 2, 3,
5, 7-1/2, 10, 15, 20, 25, 30, 40, 50, 60, 75, 100, 125, 150, 200.
LARGE MOTORS: 250, 300, 350, 400, 450, 500, 600, 700, 800,
900, 1000, 1250, 1500, 1750, 2000, 2250, 2500, 3000, 3500,
4000, 4500, 5000, 5500, 6000, 7000, 8000, 9000, 10,000, 11,000,
12,000, 13,000, 14,000, 15,000, 16,000, 17,000, 18,000, 19,000,
20,000, 22,500, 25,000, 30,000.
TABLE 9B-STANDARD VOLTAGES-INDUCTION
MOTORS
Voltage
Approximate Hp Range
110
1/2 - 20
208, 220
1/2 - 200
440, 550
1/2 - 1000
2
300
40
4000
100
-1
ro e~
4600
250
01.9 q
6600
250
13200
1000
TABLE 9C-STANDARD SPEEDS-INDUCTION
MOTORS
Speed in Rpm
(60 Cycles)
Number of
Poles
Approximate
Hp Range
3600
2
1-1/2 - 5000
1800
4
1 - 5000
1200
6
3/4 - 5000
900
8
1/2 - 10000
720
10
1/2 - 10000
600
12
1/2 - 10000
514
14
3 - 22500
450
16
3 -
400
18
50 -
360
20
50 -
327
22
50 -
300
24
50 -
v"
277
26
75 -
257
28
100 -
a.q
240
30
125 -
225
32
150 -
200
36
200 -
specify locked-rotor (starting) torque, breakdown
torque, locked-rotor (starting) current, and slip,
variations in practically all types can be obtained by
changes in the design of the rotor slots and resistance
of the rotor windings. Except for coil design, stator
construction remains the same for all types.
It is, however, advantageous to specify motors
meeting the NEMA standards, which are as follows:
A Design A motor is a squirrel-cage motor de-
signed to withstand full-voltage starting and de-
veloping locked-rotor torque as shown in Table 6,
breakdown torque as shown in Table 7, with locked-
rotor current higher than the values shown in Table
8 and having a slip at rated load of less than 5
percent*. (See Fig. 44.) Standard horsepower ratings,
voltages and speeds of induction motors are given
in Tables 9A, B and C.
A Design B motor is a squirrel-cage motor de-
signed to withstand full-voltage starting, developing
locked-rotor and breakdown torques adequate for
general application as specified in Tables 6 and 7,
drawing locked-rotor current not to exceed the
values shown in Table 8 and having a slip at rated
load of less than 5 percent*. (See Fig. 45.)
A Design C motor is a squirrel-cage motor de-
signed to withstand full-voltage starting, developing
locked-rotor torque for special high-torque applica-
tion up to the values shown in Table 6, breakdown
torque up to the values shown in Table 7, with
locked-rotor current not to exceed the values shown
To obtain normal torque with higher than normal starting
current, rotor bars are placed close to surface of rotor.
Rotor reactance is relatively low, resulting in high power
factor and efficiency.
Fig. H-44.
DESlaN- a
To obtain normal torque with normal starting current,
rotor bars are deep and narrow, producing relatively
high reactance when frequency of magnetic flux is high.
Fig. H-45.
NOTE: Some of the smaller ratings listed are not normally
gd-rot ,,
are availabotl lepp IBb O(sRa some s : ClP RDP8 0423800120045have 00102-7 tly greater
 H-18 A , proved For Release 1999/09/10 : CIA-RDP83-00423R0012004 O HT
MOTORS
TABLE 10-PERFORMANCE DATA
SQUIRREL-CAGE, CONSTANT-SPE
OPEN AND ENCLOS
D, DESIGN B MOTORS:
Di TYPES
3 PIIASI3, 60 CYCLES, 208-2
EFFICIENCIES AND POWER FACTORS
0-440-550 VOLTS
RICH MIGHT BE EXPECTED2
HP
Rpm
Efficiency
Power Factor
Full-Load Currents
Amps per Phase
(Synchronous)
4/4
3/4
1/2
4/4
3/4
1/2
220 Volts, 3 Phase
1/2
9100
66
60
53
54
45
37
2.74
3/4
1000
70
68
64
66
55
43
3
18
3/4
9;00
68
63
55
57
49
38
.
3.8
1
1800
76
74
68
71.5
62
48
3
6
1
12,00
71
70
64
67
57
45
.
4
1
1
9;00
70
66
57
60
51
39
.
4.66
1-1/2
36',00
79
76
69
84
78
67
4.48
1-1/2
1800
79
76.5
72
72.5
66
54
5.14
1-1/2
12.00
76.5
76
71
70
61
49
5.5
1-1/2
900
74
73
67
63
52
40
6.3
2
3600
81.5
78
73
84.5
78.5
68
5.7
2
1800
80
78
73
76
68
54.5
6.44
2
1200
77
76
73
71
62
50
7.16
2
9,00
75
74
69
65
55
43
8.04
3
3660
82.5
82
80
85
79
69
8
4
3
1800
81
81.5
77.5
79
73
61
.
9
2
3
1200
80
79
75
75
66
51
.
9
8
3
960
78
76
70.5
65
56
44
.
11.6
5
36)0
83.5
83.5
81
85
79
69
13.8
5
1800
85
85
83
81
75
64
14.2
5
1200
82
81.5
80
77
73
60
15.5
5
9
81
80.5
79
71
63
50
17.0
7-1/2
36 0
85
85
82
87
82
75
19.9
7-1/2
18 0
84
83.5
81
85.5
80
71
20.4
7-1/2
12 0
83.5
83
80
80
74
62
22.0
7-1/2
900
82.5
82
79
71
63
50
25.0
10
3600
86
86
84
88
84
77
26
10
1800
85
85
84
87
83
76
26.5
10
1290
84
84
83
81.5
77
68
28.6
10
900
83.5
83.5
81
80
75
63
29.4
15
3680
86
86
84
90
87
81
38
15
1800
86
86
85
87
84
76
39
4
15
12'
0
87
87
86
82
77
67
.
41
2
15
9
0
84
84
82
81
75
64
.
43.2
20
36
0
86
86
85
91
89
.84
50
20
18
0
87.5
87.5
86.5
87
84.5
79
51
6
20
12
0
87
87
86
82
77
67
.
55
0
20
9
0
86
86
85
81
75
64
.
56.4
25
36
0
87
86
85
90
87.5
33.5
62.6
25
18
0
88.5
88.5
873
87
84.5
79
63.6
25
12
0
88
88.5
87
86
83.5
72
64.8
25
9
0
87
87
86
82
76
66
68.8
30
360
0
89
88
86
90
87.5
133.5
734
30
180
0
89
89
88
88
85
80
75.0
30
120
0
88.5
89
88
87.5
85.0
73.5
76
30
90
0
88
88
87
82
78
70
81.4
40
3600
89
88
86.5
90
87.5
83.5
98
40
1800
89
89
88
88.5
86
81
99
6
40
1200
89 _
89
88
88
84.5
78
.
100
0
40
900
.
108.0
50
3600
89
88
85.5
89
87
113.5
124.0
50
1890
89.5
89.5
88
89
87
.112
123.0
50
120;0
89.5
89.5
88
88
84.5
78
124.4
50
900
88.5
88.5
87
83
79.5
71
134.0
60
3600
90
89
87
90
89
85
145
60
18010
90
90
89.5
89
87
112
147
60
12001
,
89.5
89.5
88.5
87.5
84.5
76
150
60
go
88.5
88.5
87
83
79.5
71
160
75
1
3601
90.5
90
88
89.5
883
84.5
181
75
1800
90
90
89
89
87
82
184
75
1209
90
90
89
87.5
84.5
76
187
75
900
89
89
88
86
84.5
74
192
1 For 2-pole, totally-enclosed fan-cooled motors, efficiency should be reduced 1% at 4/4 load, 2% at 3/4 load, and 3% at 1/2 load.
2 Not to be used for guarantees; consult motor manufacturer?
3 Full-loadArp ybin! fov`
fts IaS M VOM ee( 4 DP813d80A RcOW.200450002-7
 P83-60423R0012004500 H-19
Approved For Release 1999/09/10: CIA-REWCTioN
MOTORS
LOW R#S/STQ4'CE W/ND/NG
To obtain high starting torque with low starting current,
two sets of rotor bars are used. The operation of this type
is described under the heading "Double-Cage Motors."
Fig. H-46.
"ED/UM LEHKRGE FLUX
HIGN RES/STANCE WIND/MG
0ES/GN- D
To obtain high starting torque with normal starting
current, thin high-resistance bars are used, producing
relatively high reactance.
Fig. H-47.
inTable 8 and having a slip at rated load of less
than 5 percent. (See Fig. 46.)
A Design D motor is a squirrel-cage motor de-
signed to withstand full-voltage starting, developing
high locked-rotor torque as shown in Table 6, with
locked-rotor current not greater than shown in
Table 8 and having a slip at rated load of 5 percent
or more. (See Fig. 47.)
NOTE: Standard speeds for most 25-cycle motors
are 1500, 750 and 500 rpm for which no torque values
have been established.
Typical Applications
Design A motors obtain higher breakdown torque
than Design B motors, but they do this at the expense
of higher locked-rotor current.
Design B motors are the standard, forming the
basis for comparative motor performance of all other
types. Their torque, starting current and slip char-
acteristics make them suitable for most applications.
Efficiency is relatively high-even under fractional
loads. Power factor is also good at full load, although
it does decrease quite rapidly with decrease in load.
Both efficiency and power factor decrease as the number
of poles increases. (See Table 10.)
Design A and B motors are used for such constant-
speed applications as light conveyors, line shafts,
blowers, fans, woodworking machines, rotary com-
esign
but lower breakdown torque than Design B motors,
while locked-rotor current and slip are the same for
the two designs. Design C is for applications requiring
high initial torque to start, such as vibrating screens,
conveyors, milling machines, pulverizers, reciprocating
pumps, crushers, and compressors without unloading
devices. It should be noted that while these motors
develop high starting torque, they are not intended
for applications requiring frequent starting and
stopping.
Design D motors have high torque and high slip.
They are generally used on applications involving
high inertia and frequent load changes, such as fly-
wheel-equipped punch presses. The high slip enables,
the motor to pick up the load when the excess energy
stored in the flywheel has been released during the
working stroke of the cycle. The high torque enables
the motor to repeatedly accelerate the load to full
speed, without overheating, to restore energy to the
flywheel. This alternate supplying and releasing of,
power irons out the load peaks, that is, the maximum
power demand. Other applications include elevators,'
metal drawing, shears, hoists, and bailers.
Double-Cage Motors
A double-cage motor is a polyphase induction motor
having a rotor with two separate squirrel-cage wind-
ings, one within the other, as shown in Figs. 48 and 49.
The stator is of standard construction. Double-cage
construction is used only when it is necessary to obtain
high starting torques with relatively low starting
current. It provides higher starting torques than
ordinary single-winding motors, but not as high
torques as single high-resistance winding motors.
In a double-cage motor, the outer cage has high
resistance and the inner cage has low resistance. The
former provides high torque in starting, while the
latter carries most of the current at full load.
,9-LOW RESISTANCE
SOU/RR#L CRGE
C-STRTOR W/NDINO' B-NIGH RESISTRNCE
SQUIRREL GRGE
This diagram shows two things: (a) Typical rotor and
stator slot shapes used in small double-cage rotors.
(b) Relative current flow at time motor is ready to start;
most of current is carried by high-resistance outer cage
bars, giving high starting torque with low starting current.
 INDUC roved For Release 1999/09/10 : Cl
iivDUc
MOTORS
srRTOR CORE
R-LOW RES/STANCE C-STHTOR WINO/NF B-H/Gh RES/STRNCE
S4U/RREL CRGE SQC'/RREL CI9aE
(a) Typical rotor and s tator slot shapes used in large
double-cage motors. (b) *elativc current flow when motor
has reached normal sped, most of current is carried by
low-resistance inner cage, giving high efficiency during
operation.
Fig. H-49.
Figs. 48 and 49 shovlr that the inner cage bars are
more completely enclosed by stator core iron than
are the outer cage bars. Thus the magnetic path
around the inner cage bars is more satisfactory than
that around the outer bars. This, however, means
that the path around the inner bars has greater in-
ductance.
Now, at the instant of starting, the revolving field
produced by the stator current induces currents in
both sets of rotor conductors-at full line frequency.
But at full line frequency, the high inductance of the
inner winding impedes he current in the inner con-
ductors.
However, even at fulfil line frequency, considerable
current is set up in the outer conductors since they
have relatively low inductance. But this is a high
resistance winding, and this plus the choking action
of self-induction at line frequency limits the current
in starting.
In Fig. 48, the depth of shading indicates the com-
parative density of the currents in the two sets of
conductorswhen the motor is ready to start.
As the rotor gains speed, the frequency of the cur-
rents induced in the rotor decreases, and the relation-
ship between the currerts in the two squirrel cages
automatically changes. This is due to the fact that
the frequency of the induced currents is proportional
to the slip, and at normal speed this frequency be-
comes only a few cycles er second.
At this low frequency, the higher inductance of the
inner cage windings produces only a small choking
effect. Therefore the resistances of the two cages are
the essential factors influencing the distrijution of
and limiting the flow of the rotor currents. Thus, at
normal speed the greater part of the total rotor current
is carried by the low-resistsance inner cage, as indicated
CPYRGHT
RDP83-00423R001200450002-7 .
and-rotor motor are quite similar to those of the
he general principles of operation of the polyphase
g. 50 shows a standard wound-rotor motor.)
rt-circuited or closed' through suitable circuits.
lyphase winding or coils whose terminals are either
tor in which the secondary circuit consists of a
lap-rang motor, is defined, by NEMA as an induction
A wound-rotor induction motor, sometimes called
OUND-ROTOR MOTORS
yphase squirrel-cage type.
he essential structural difference between the
and-rotor motor and the squirrel-cage motor is in
rotor. The wound-rotor motor has a distributed
se-wound rotor winding arranged for the same
ber of poles as the stator winding. The terminals
the rotor winding are connected to three collector
(slip rings) mounted on the shaft (Fig. 51). From
shes riding on the collector rings, leads are brought
for connection to a secondary control-which
vides resistance for starting or speed regulating
poses.
o increase the speed, the resistance is gradually cut
of the circuit until, for operation at full speed, the
r winding is short-circuited through the control.
he torque of a polyphase induction motor is a
tion of its impedance,: and the function of the
nd-rotor motor secondary control is to change
impedance to an optimum value. By properly
ortioning the external resistance, it is possible
btain a locked-rotor torque that is nearly equal
Fio. H-50. Open, drip-proof wound-rotor motor.
by the sha$r;g ,- d or Release 1999/09/10 : CIA-PtDFli6 -00rAPZRG1Qd QM, Q.QDZ;7
 Approved- For Release 1999/09/10 : CIA-RDP83-0RM6MI0045000~H 21
UCTION
MOTORS
to the breakdown torque, and this can be done with
much lower locked-rotor (starting) current than with
squirrel-cage motors.
Wound-Rotor Motor Advantages
The wound-rotor motor thus has some very distinct
advantages over the squirrel-cage motor:
a) It can develop high starting torque with rela-
tively low starting current. This characteristic makes
it suitable for high load-torque drives where starting
current must be limited.
As noted above, it is possible to obtain starting
torques nearly equal to the breakdown torques. This
depends on the external resistance in the rotor circuit
and its method of distribution. The breakdown torque,
with collector rings short-circuited, is not less than
.200 percent for general-purpose ratings, and larger
values can be obtained for special load requirements.
b) The major portion of the heat developed during
starting can be dissipated in the external resistors
(provided that they are suitably proportioned) instead
of being concentrated in the rotor winding, as is the
case in squirrel-cage motors. This makes the wound-
rotor motor suitable for drives having such high load
inertia as to be beyond the thermal capacity of the
starting windings of squirrel-cage or synchronous
motors.
c) The wound-rotor motor can be used for ad-
justable-varying speed regulating duty for such ap-
plications as fans, cranes, hoists, etc. It should be
noted that this does not, however, provide good speed
regulation on non-steady loads as the speed changes
with changes in load, due to the slip inherent in in-
duction motors. The percentage of speed reduction
obtainable depends on the character of the load; a
50 percent reduction is usually permissible on variable
torque loads without producing unstable operation.
The temperature of the motor will usually be higher
at reduced speeds, due to the reduction in normal
ventilation.
Other Characteristics
When a wound-rotor motor is operating at full speed
with the secondary short-circuited through the control,
its operating characteristics are very similar to those
of a normal-torque, normal starting-current cage motor.
The main differences are usually slightly lower slip
(2 percent for larger sizes to 5 percent for smaller ones)
and somewhat lower power factors (due to certain
magnetic "leakage" factors inherent in the design).
Wound-rotor motors are limited to two xe spee
because of complications in rotor construction. How-
ever, each "fixed" speed is capable of further speed
adjustment in the same manner as outlined above
for single-speed motors of this type. For example, the
speed can be adjusted from the higher one through
the range to the lower fixed speed.
Multi-speed squirrel-cage construction constitutes
the simplest form of adjustable-speed motor, since
there are no brushes, commutators or collector rings
involved. Its principal drawback lies in the fact that
it provides only the two, three or four speeds for which
it is designed-there are no intermediate speeds.
Construction Principles
The stator may have either one or two windings, each
of which will produce either one or two of the desired
rotor speeds-depending upon the ratios of the various
speeds required.
Two-speed motors (for operation on 3-phase circuits)
having a speed ratio of 2 to 1 (1800 and 900 rpm, or
1200 and 600 rpm, for example) are usually furnished
with a single stator winding. The two speeds are ob-
tained by means of a selector switch which renders
either all or half of the poles effective. With all of the
poles effective, the motor operates at the low speed;
with half of the poles effective, it operates at the high
speed. This is called a consequent-pole winding, and
the low speed is always one-half of the high speed.
If the two speeds required are not in a 2 to 1 ratio,
two separate stator windings are required. This applies
to such speed ratios as 1200/900 rpm or 1800/1200 rpm.
When three or four speeds are required, the motor
is built with two separate windings, with one or both
of the windings being of the consequent-pole type.
This permits speed ratings such as 1200/900/600 rpm
or 1800/1200/900/600 rpm. Diagrams of windings and
coil connections of consequent pole motors are shown
on pages 124 and 125, Section F.
Torque Characteristics
Multi-speed motors are available with any
the following three torque characteristics:
Constant-horsepower motors produce the same horse-
power output at all speeds. They are used for lathes,
boring mills and other machine tools where the torque
demand decreases as the speed increases.
Constant-torque motors produce the same torque at
all speeds and the horsepower is in direct proportion
to the speed. These motors are used for conveyors,
stokers, etc.
MULTI-SPEED INDUCTION MOTORS
Multi-speed squirrel-cage motors can be designed
t ate at two three or four speeds-having con-
e
Variable-torque motors produce a torque that de-
creases with the speed, resulting in a horsepower
output which decreases with the square of the speed.
Atl"e dtFiMcRelea 9/09/10 : C IA 'D UU64223 '1 ( 0 fo er require-
stant
 CPYRGH-T.
H"ZTAooroved For Release 1999/09/10 : CI -RDP83-00423 R001200450002-7
INDUCTJdt4
MOTORS
TABLE 1-SUMMARY OF PROTECTION AN
Standard
Type of
Approximate
Temperature Rise
Enclosure
I Range of Sizes
Class A
Insulation
l1/2 hp and larger
Semi-protected
1/2 hp and larger
50 C
Protected
1/2 hp and larger
50 C
Frame 224 and larger
Enclosed, forced-
Frame 364 and larger
ventilated
Enclosed, self-
Frame 364 and larger
ventilated
Totally-enclosed,
Fkames 204 to 254
non-ventilated
Totally-enclosed,
Frame 254 and larger
fan-cooled
TABLE 12-REPRESENTATIVE CAGE MOT
Open D4-Proof
ENCLOSURES-INDUCTION MOTORS
Approximate Application
Cost Increase Information
0 to 10% Protection against dripping liquids or
falling: particles.
5% Same as protected.
10% Protections against metal chips in
machine shops, cite.
10 to 15% Protections against dripping and splash-
ing liquids; used in breweries, food
plants, dairies, etc.
4 to 20% Same as fis-cooled..
40 to 115% Used where abrasive dust, dirt, grit,
or corrosive fumes are too severe for
open moltors-in ruetal-working
plants, ;foundries? machine shops,
etc.
10 to 20% For oil refineries, varnish plants, lac-
higher than quer plants, or others where flam-
fan-cooled mable, Ivolatile liquids are manu-
factured, used or handled.
R DIMENSIONS (IN INCHES)
Splash-Proof
Frame
A$
Bj
i C
D t
Et
Ft
L
M
N
0
P
Ut
W
AL
AM
AN
ACOt
A12f
Keyt
203
204
99(
6%
J3%
5
4
2%
53
5%
2%
9%
9?/a
.750
3a
14
11
6%
5
49(
%x%al
224
9%
7%
14%
1
5
4
33
634
634
2%
9%
95%
.750
38
14
12
6%
5
53(
%z%a1
225
109(
8%
6%
534
434
3%
69(
69(
3%
10%
10 98
1.000
38
1534
;
123,(
7%
534
5%
3(z3ja2
254
109/
9
17%
534
43
3%
738
7%
3%
10%
10%
1.000
3
1534
13'
7%
534
594
3483x2
119(
10
40
6%
5
43a
834
8X
33
12 V,
11%
1.125
3a
17%
1533
8%
63 41
6%
348/x298
284
324
129(
1134
22 %
7
534
49(
9%
9%
3%
13%
2 %
1.250
38
199(
16 T/,i
9
7
7A
(x 3(x2%
326
14%
8
12%
25%
2
8
634
53
1D%
10%
5%
15%
4%
1.625
%
223/4
1939;
1034
8
8%
/
s8%s3%
364
%
14
1738
1434
14
7%
2
8
634
6
11%
113(
536
15%
4%
1.625
%
229(
20%
1038
8
934
8
%x %x3(
8 %
9
7
598
1134
1134
5%
179
7 %
1.875
34
2538
2035
1134
9
9 y
34z34s4 34
364-S
365
1734
14
2 6
9
7
5 %
1134
1134
334
17%
7%
1.625
34
365-S
17A
173
15
15
29%
27
9
7
638
119(
119(
5%
17%
7%
1.875
3j
253
2134
1138
9
9%
3aa34s43(
9
7
638
11%
1184
33;
179(
7%
1.625
34
....
..
..
..
988%zlY8
9%
2.125
34
2838
22
13
10
9%
34z34a5
404-S
405
1938
19
153
1
29
10
8
638
1:134
12,14
4
19,%
9%
1.875
%
....
....
....
....
3/8x3482
405-S
34
19
6%
3$ YS
0
10
8
6%
1'; Y4
13%
6%
199%
9%
2.125
34
2834
233
13
10
109
34834x5
444
34
21
16%
3
38
5
10
8
6%
1:43(
1334
4
19.%
9%
1.875
34
....
....
....
34z35z2
444-S
34
2134
1734
17
3
38
$
11
9
7%
154
14
7%
21%
134
2.375
%
31
24 4
14
11
11
988 %x534
34
3
11
9
7%
144
14
5
21%
134
2.125
3(
....
....
....
....
...
34z34z2%
445
445-S
2134
21
19%
1
3;%
11
9
8Y,
15
15
7%
21%
134
2.375
3%
31
2634
14 :
11
12
%z /x534
34
9%
3
11
9
834
15
15
5
21%
1A
2
125
%
504-U
2434 19 4 v
12 1 8
.
....
...I
....
35z34z2U
505
a
Appioved4 orme4ease '~
9I
24, I
4
J
~a/a734
 mppruvt;ca rur mwiucrsu i ziuvivvi i v : .w-muroo-vv,+zomL( `Jp plgvvL
INDUCTION
MOTORS
STANDARD OPEN DRIP-PROOF AND SPLASH-PROOF STANDARD TOTALLY-ENCLOSED MOTORS
MOTORS (60 CYCLES) (60 CYCLES)
HP
3600
1800
1200
900
720
600
Motors above line are non-ventilated.
1/2
....
....
....
204
224
225
Motors below line are fan-cooled.
3/4
.
203
224
225
254
1
...
....
....
203
204
225
254
254
Hp
3600
1800
1200
900
720
600
1-1/2
203
204
224
254
254
284
1/2
....
....
....
204
224
225
2
204
224
225
254
284
324
3/4
....
....
203
224
254
254
3
224
225
254
284
324
326
1
....
203
204
225
254
254
5
225
254
284
324
326
364
1-1/2
204
204
224
254
254
284
7-1/2
254
284
324
326
364
365
2
204
224
225
254
284
324
3
224
225
254
284
324
326
10
284
324
326
364
365
404
5
225
254
284
324
326
365
15
324
326
364
365
404
405
7-1/2
254
284
324
326
365
404
20
326
364
365
404
405
444
10
284
324
326
364
404
405
25
364S
364
404
405
444
445
15
324
326
364
365
405
444
30
364S
365
405
444
445
504U
20
326
364
365
404
444
445
40
365S
404
444
445
504U
505
25
365S
365
404
405
445
504U
50
404S
405S
445
504U
505
....
30
4045
404
405
444
504U
505
60
405S
444S
504U
505
....
....
40
405S
405
444
445
505
75
444S
445S
505
....
....
....
50
444S
444S
445
504U
100
445S
504S
....
....
....
....
60
4458
445S
504U
505
125
504S
5055
....
75
504S
504S
505
150
5055
....
....
....
....
....
100
505S
505S-
TABLE 12-REPRESENTATIVE CAGE MOTOR DIMENSIONS (IN INCHES)-Continued
Frame
At
Bt
C
Df
Et
Ft
L
M
N
0
P
Ut
W
AL
AM
AN
AOt
ARt
Keyt
203*
9%
6%
13 34
5
4
2%
5%
5 6%
2%
9%
9%
.750
34
14
11
6%
5
4%
Xx X135
204*
9%
7%
14%
5
4
334
634
6%
2A
9%
93%
.750
34
14
12
6%
5
534
%z%az1%
224*
10%
8%
16%
5%
4%
3%
6%
6%
334
10%
10% .
1.000
34
15%
12%
734
534
5%
34x%x2
225*
10%
9
17%
534
4%4
3%
73s
7
3%
10%
10%
1.000
34
1534
13
7%
534
534
3(z %z2
254
11%
10
22%j
6%
5
438
10%
838
3%
12
1134
1.125
34
17%
1538
834
634
6%
%%34x238
284
12%
11%
24%
7
5%
434
11%
934
3%
1334
12%
1.250
34
19%
16%
9
7
734
1%z%z2%
324
14%
12%
2834
8
634
534
12%
10 %
538
15%
1534
1.625
34
22%
1934
1034
8
8%
%x%z334
326
14%
14%
29%
8
634
6
13%
11
5%8
15%
1534
1.625
34
20%
22%
1034
8
934
%a%a3%
364
17%
14
31 %
9
7
5 %
14
1134
5%
18%
19
1.875
34
25%
20%
11%
9
938
34x3484%
364-S
1734
14
28%
9
7
5%
14
1134
334
1834
19
1.625
34
..
....
..
...
*
..
%.%x1%
365
1734
15
323s
9
7
6%
14%
11%
5%
1834
19
1.875
34
25%
21%
1134
9
9 %
%z34z434
365-S
1734
15
29%
9
7
638
1434
11%
334
1834
19
1.625
34
....
...
%z38z1 %
404
1934
1534
3434
10
8
638
15%
1234
6%
2068
20 %
2.125 .
34
2834
22
13
10
9 %
34z34z5
404-S
1934
1534
31%
10
8
636
1534
1234
4
2038
20 %
1.875
34
....
....
....
....
....
34xMx2
405
1934
16%
35%
10
8
6%
16
1334
634
2034
20%
2.125
34
28%
2334
13
10
10%
3az3az5
405-S
19%
16%
3334
10
8
6 %
16
1334
4
20%
20 %
1.875
34
....
....
....
....
....
%z%z2
444
21%
1734
3934
11
9
734
17%
1434
7%
22%
23%
2.375
34
31
24%
14
11
11
%x%853
445
2134
19M
41%
11
9
8%
18%
1534
7%
22%
2334
2.375
34
31
2634
14
11
12
%z %x5%
445-S
21%4
1934
38%
11
9
834
18%
1534
4%
22%
2334
2.125
34
....
....
....
....
....
3483482%
504-U
2434
21
4436
1234
10
8
19
16 %
834
24%
2434
2.875
34
3434
27 34
16
1234
1234
348%8734
505
2434
23
46 %
1234
10
9
20
1734
8%
2434
24%
2.875
34
34%
2934
16
12A
13%
348348734
*Dimensions shown for these frames are for totally-enclosed non-ventilated construction.
tThese are NEMA standard dimensions. Other dimensions may vary, depending upon the manufacturer.
:These PllVrCY'dtPP rnRClLy'tbSLP".7.7/V.7/'IVMACIA-RDP83-004238001200450002-7
 H-24 Approved For Release 1999/09/10 : Cl -RDP83-00423R001200450DQrHT
INDUCTION
MOTORS
ments of a fan decreas' approximately as the cube
of the speed.
Squirrel-cage multi-speed motors are built to the
same NEMA design standards for torques and starting
currents as single-speed pnotors.
!
MOTOR PROTECTIO14
Classification of maclines by types of mechanical
protection and methods of cooling will be found in
the definitions of pages 4 to 9. Accompanying illustra-
tions, Figs. 5 to 28, inclusive, show the construction
employed for the various types, and Table 11 gives a
brief summary of such, features. This table shows
(a) the approximate range of sizes or ratings in which
each type is built, (b) tlie maximum temperature rise
for Class A insulated machines, (c) the approximate
increase in cost over tllie standard open type, and
(d) application suggestions.
STANDARD DIMENSIONS
Table 12 gives representative dimensions for foot-
mounted motors, while Table 13 shows representative
frame sizes for various horsepower and speed ratings
in open drip-proof and totally-enclosed motors.
tota ly-enclosed types are also available, as well as
vert cal types.
Performance and cost are b.sually consistently better
tha for direct-connected motors of the same output
spec is. For smaller ratings, !gearmotor construction is
the only practical answer for low output speeds.
Figs. 52 and 53 show two types of gearmotors.
Ratings and Classifications
U its of this type are available in ratings up to 50
hp or all applications and up to 75 hp for some ap-
plications. Table 14 gives output speeds listed in the
NE 1A Recommended Standards, but it should be
not that some of these speeds, namely 1430, 1170,
950, 6, 5, and 4 rpm, are seldom used and are not always
avai able.
Aft
Gearmotors meet the demand for a highly efficient,
economical and dependable source of power for low-
speed drives. Basically, a gearmotor consists of a
1750-rpm motor and a double-, triple- or quadruple-
reduction gear unit. The standard motor is the squirrel-
cage type, but wound-rotor and direct-current motors
are occasionally used.
Construction
The gear units use precision-cut gears, some manu-
facturers using the helicaljtype and others the planetary
type. The gear efficiency usually is not less than
97 percent.
High efficiency and, in jthe case of induction motors,
good power factor result: from the use of high-speed
motors. Motors usually are of the standard open
drip-proof type, but in most cases splash-proof or
ravrer_iaT...
TAB .E 14-OUTPUT SPEEDS FOR INTEGRAL-HORSE-
PO ER GEARMOTORS OF PARALLEL CONSTRUCTION
ominal Nominal
Gear Output Gear Output
Ratios Speeds Ratios Speeds
1.225 1430 25.628 68
1.500 1170 31.388 56
1.837 950 38.442 45
2.250 780 47.082 37
2.756 640 57.633 30
3.375 520 70.623 25
4.134 420 86.495 20
5.062 350 105.934 16.5
6.200 280 129.742 13.5
7.594 230 158.900 11.0
9.300 190 194.612 9.0
11.390 155 238.350 7.5
13.950 125 291.917 6.0
17.086 100 357.525 5.0
20.926 84 437.875 4.0
These output speeds are based on an assumed operating
spec of 1750 rpm and certain nominal gear ratios and will
be modified:
1.. By the variation in individual motor speeds from the
basic operating speed of 17,150 rpm.
(The same list of outputispeeds may be applied to 25-
or 50-cycle gearmotors when employing motors of 1500
rpmsynchronous speed if ;an assumed motor operating
speed of 1430 rpm is used.);
(This list of output speeds may be applied to 60-cycle
gearmotors when employing motors of 1200 rpm syn-
chronous speed if an assumed motor operating speed of
1165 rpm is used.)
2. By a variation in the exact. gear ratio from the nominal,
which variation will not chaiige the output speed by more
than plus or minus 3 per cent.
foot-mounted motors-recommended when Fig. H-53. Integral-type gearrmotor uses round-frame
Approved w lease 1999/09/10: n Or*0@42 RO@tl"4800W-lbngth.
 Approved For Release 1999/09/10 : CIA-RDP83-00423R0M0002-7 H-25
INDUCTION
OAGI4RS
AGMA recommended practice calls for three classi-
fications of gearmotors as follows:
Class I-For steady loads not exceeding normal
rating of motor and 8 hours a day service. Moder-
ate shock loads where service is intermittent.
Class II-For steady loads not exceeding normal
rating of motor and 24 hours a day. Moderate
shock loads for 8 hours a day.
Class III-Moderate shock loads for 24 hours a
day. Heavy shock loads for 8 hours a day.
As shown by Table 15, gearmotors in these various
classifications are available for most applications. To
assure proper selection of units, it is essential that the
manufacturer be given complete application data.
TABLE 15-COMMONLY AVAILABLE GEARMOTOR
RATINGS
Output Rpm
Hp
(1750 Rpm Motors)
Class I
Class II
Class III
520, 420, 350
1 to 50
1 to 50
1 to 40
280,
230,190, 155
1 to 50
1 to 50
1 to 50
125
1 to 50
1 to 50
1 to 40
100
1 to 50
1 to 50
1 to 30
84
1 to 50
1 to 30
1 to 25
68
1 to 40
1 to 30
1 to 20
56
1 to 40
1 to 25
1 to 30
45
1 to 30
1to20
1to15
37
1 to 25
1 to 20
1 to 10
30
1 to 20
1to15
1to10
25,20
l to 15
Ito10
1to7.5
16.5, 13.5
1 to 10
1 to 7.5
1 to 5.0
11.0, 9.0
1 to 7.5
1 to 5.0
1 to 3.0
7.5
1 to 5.0
1 to 3.0
1 to 3.0
TABLE 16-OPERATION;ION OFF-STANDARD VOLTAGES AND FREQUENCIES
VALUES SHOWN ARE FOR GENERAL-PURPOSE DESIGN B CAGE MOTORS AND WILL
VARY SOMEWHAT FOR DIFFERENT RATINGS AND DESIGNS.
*Torque
Locked-rotor and breakdown
(Speed
Synchronous
Full load ....................
Percent slip ................
Efficiency
Full load ....................
3/4 load .....................
1/2 load .....................
Power factor
Full load ....................
3/4 load .....................
1/2 load .....................
Current
Locked-rotor ................
Full load ....................
Temperature rise
Maximum overload capacity...
Voltage (in percent of rated)
110% 90%
No change
Increase 1%
Decrease 17%
Increase 0.5 to 1
Little change
Decrease 1 to 2
Decrease 3%
Decrease 4%
Decrease 5 to 6%
No change Increase 5%
Decrease 1.5% Increase 5%
Increase 23% Little change
Decrease 2 Slight increase
Little change Slight increase
Increase 1 to 2 Slight increase
Increase 1% Slight increase
Increase 2 to 3% Slight increase
Increase 4 to 5% Slight increase
Increase 10 to 12% Decrease 10 to 12% Decrease 5 to 6%
Decrease 7% Increase 11% Slight decrease
Decrease 3 to 4 C Increase 6 to 7 C Slight decrease
Increase 21% Decrease 19% Slight decrease
Magnetic noise ................ Slight increase Slight decrease Slight decrease
*The locked-rotor and breakdown torque of ac induction motors will vary as the square of the voltage.
tThe speed of ac induction motors will vary directly with the frequency.
OPERATION ON OFF-STANDARD
VOLTAGES AND FREQUENCIES
Guarantees of motor characteristics (torque, power
factor, efficiency, etc.) are based on operation of the
motor at rated (nameplate) voltage and frequency.
As explained earlier, under the heading Service Condi-
tions, motors will operate successfully despite some
deviation from rated values, but not necessarily in
accordance with the standards established for operation
under rated conditions. Table 16 shows the approxi-
mate effects of variations in voltage and frequency
on motor performance. The values will vary somewhat
with the rating of the motor.
SYNCHRONOUS MOTORS
A synchronous motor is defined by NEMA as a
Decrease 5%
Decrease 5%
Little change
Slight decrease
Slight decrease
Slight decrease
Slight decrease
Slight decrease
Slight decrease
Increase 5 to 6%
Slight increase
Slight increase
Slight increase
Slight increase
from an alternating-current system into mechanical
power. Synchronous motors usually have direct-
current field excitation.
A synchronous motor consists essentially of a
stationary armature (stator) and a revolving field with
windings arranged for excitation from a source of
direct current. Fields of motors with four or more
poles are of the salient pole type. Two-pole motors,
which are seldom used except in very large sizes, are
usually of the non-salient pole type and are similar to
steam-turbine-driven synchronous generators.
The speed of a synchronous motor is a function of
the number of poles. It remains in synchronism with
the supply frequency and is unaffected by the load.
(See Table 1.)
Efficiencies are generally higher than for induction
synchrgoW,8,V6( '`&*6li6%rW& *oby,V! ClA DP834E} B4 4d( ' cularly so
 H-26 Approved For Release 1999/09/10: Cl -RDP83-00423ROO12004500o '7{RGHT
SYNCHRONOUS
MOTORS
Fig. H-54. Engine-type, 6b0-hp, 150-rpm synchronous
motor driving 450-ton-pe!-day ammonia compressor.
in the case of unity powei factor motors and/or lower
speeds.
Application of synchronous motors requires careful
consideration of all factor involved, especially:
Power factor.
Locked-rotor (static) toque.
Pull-up (accelerating) torque.
Pull-in torque,
Pull-out torque.
Effect of load inertia o'n pull-in torque and thermal
capacity of the am rtisseur winding.
Effect of voltage variation on torques.
POWER FACTOR
Normally, one does not think of induction .motors as
requiring excitation, but actually they do. The fact is,
the exciting current is supplied from the 'line. And
because the magnetizing !component lags 90 degrees,
the result is that the line current lags at all loads to an
extent depending on the r agnitude of the magnetizing
current.
In synchronous motors the excitation is supplied to
the field from a separate dc source. Thus, by varying
the field strength, the phase relationship (power
factor) of the armature current. and voltages may be
changed. With a given field strength the power factor
is unity; that is, the armature current is a minimum
and in phase with the voltage.
Decreasing the field strength causes the increasing
current to lag, increasing the field strength causes the
increasing current to lead] the voltage. In other words,
lagging or leading powe . factor results. Synchronous
motors can therefore be made suitable for power-factor
correction purposes.
The above should not be interpreted to mean that Wk2
any such motor is necessarily suitable for operation at in t
other thanAliPPfM 0raReIeA$0499 YA9/10 : Cl
ING
rtisseur Winding
armature (stator) winding is wound for operation
a polyphase (2 or 3-phase) source. When voltage
lied at the terminals, a revolving; magnetic field
duced in the stator; its speed is proportional to
equency and number of 'poles.
rotor assembly contains, an amortisseur winding
pole faces. This winding is similar to the cage
ng of an induction motor. It is shown in Fig. 55.
revolving field of the armature acting on the
isseur winding produces (a) the static torque
auses the motor to break from rest and (b) the
p torque for acceleration. Depending upon the
of load and the resistance of the amortisseur
ng, the motor will accelerate to a speed of from
percent below synchronous speed..
us, the synchronous motor is actually started and
ht up to near synchronotis speed as a squirrel-cage
r. Then the field excitation is applied. If the motor
:
application, the field of
perly designed for the
otor will "pull in" and. lock in step with the
ng magnetic field of the stator.
t of Load Wk2
rtain types of drives are characterized by high
inertia (load Wk2), as indicated by Table 18. The
inertia which a synchronous motor can accelerate
finitely limited by the thermal capacity of its
tisseur winding.
aller motors can accelerate relatively higher load
than larger motors, until a point may be reached
e very large sizes where the motor may be capable
82342d0O2.
oft
 Approved For Release 1999/09/10: CIA-RDPO0049WO01200450002- 1-27
Fig. H-56. Besides driving 3000-gpm pumps, these
500-hp synchronous motors improve plant
power factor.
As indicated by the NEMA definition of pull-in
torque on page 4, the matter of load Wk2 has a most
important effect on the pull-in capabilities of syn-
chronous motors.
Effect of Voltage on, Torques
It must be remembered that all torque values listed
are based on full voltage at the motor terminals.
Hence, if the voltage at the terminals is below rated
voltage, the starting and pull-in torques should be
based on values adjusted to compensate for the re-
duction in voltage so that the required torques will be
obtained with the actual voltage at the terminals.
This condition exists when reduced-voltage starting
is used and/or when the line voltage drops below rated
voltage during the starting period.
Starting and pull-in torques vary approximately as
the square of the voltage.
For example, suppose you have an application that
requires 100 percent starting torque (static torque)
and 100 percent pull-in torque. Suppose also that
reduced voltage starting on 85 percent tap and pull-in
on full voltage is to be used but that line voltage will
drop to 95 percent during the starting and pull-in
period. You would then require a motor with rated
starting and pull-in torques as follows:
Starting torque = 100 = 153%
0.852 X 0.952 _
Pull-in torque = U 952 = 111%
torque. The increased torque requirement is produced
by a backward shift or lag in the position of the field
poles with respect to the revolving magnetic field. The
motor, however, still maintains its synchronous speed.
The motor develops its maximum torque when the
field poles have shifted backward approximately one-
half the distance between adjacent poles. Any further
increase in load will cause the motor to pull out of
step and stop.
The maximum torque that a motor will develop
without pulling out of step is called its pull-out torque.
Typical pull-out torque requirements for various
SYNCHRONOUS MOTORS
TABLE 17A-STANDARD HORSEPOWER RATINGS
GENERAL-PURPOSE MOTORS: 30, 40, 50, 60, 75, 100,
125, 150, 200*.
LARGE IIIGII-SPEED: 200**, 250, 300, 350, 400, 450,
500, 600, 700, 800, 900, 1000, 1250, 1500, 1750, 2000, 2250,
2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 7000, 8000,
9000, 10,000, 11,000, 12,000, 13,000, 14,000, 15,000, 16,000,
17,000, 18,000, 19,000, 20,000, 22,500, 25,000, 27,500,
30,000.
LOW-SPEED: 20, 25, 30, 40, 50, 60, 75, 100, .125, 150, 175,
200, 225, and larger ratings as listed above for large
highspeed motors.
*At 1.0 pf. **At 0.8 pf.
TABLE 17B-STANDARD VOLTAGES
Voltage Approximate Hp Range---1.0 Pf
208, 220 20 - 200
440, 550 20 - 1000
2300 20 - 10000
4000 75 - 17000
4600 75 - 20000
6600 400 - 30000
13200 1000 - Any
Speed in Rpm Number
(60 Cycles) Poles
3600
1800
1200
900
720
600
514
450
400
360
327
300
277
257
240
225
200
180
164
150
138
128
120
109
100
95
90
86
80
of Approximate Hp
Range--1.0 Pf
1000 & Larger
30 - 5000
30 - 10000
30 - 30000
40 - 30000
50 - 30000
100 - 30000
20 - 10000
20 - 10000
20 - 10000
20 - 10000
20 - 10000
20 - 10000
20 - 10000
20 - 10000
20 - 10000
20 - 10000
20 - 10000
20 - 10000
50 - 10000
60 - 10000
75 - 10000
100 - 10000
100 - 10000
100 - 10000
150 - 10000
150 - 10000
150 - 10000
150 - 10000
re
pose ion w p
of the armature. A load applied to the motor develops Standard speeds for other frequencies will be proportionate
to the fre uenc using the pole groupings listed above for 60
a torq A d cFsaR@fsi3swr"99/G9/1QQ1: CIA- DP 3-60423 R001200450002-7
PULL-OUT TORQUE
When a synchronous motor is operating at no-load,
the individual field poles of the motor have a fixed
s ect to the revolving magnetic field
t' ith
 "28Approved For Release 1999/09/10 : CIA-RDP83-00423R00120a0MWT
The following, taken in the main from NEMA MG1-8.9, represent ypical locked-rotor, pull-in and pull-out torque requiremen
of various synchronous motor applications.
In individual cases, lowjr values may be satisfactory or higher value may be necessary, depending upon the characteristics of th
particular machine and the effect of locked-rotor kva on the line voltage.
TYPICAL TORQUE REQUIREMENTS
In P cent of Full-Load Torque Max.
APPLICA7iION "Load
1-CENTRIFUGAL MAcIIINERY-Blowers, Compressors, Fans and Pumps
12 Blowers .............i................. ..... ..... ..... ..... ..... 10-15
is Compressors. ........i ................. ..... ..... ..... ..... 15-25
1 Fans-(except sintering) ............... ..... ..... ..... ..... ..... 20-50
4 Inlet or discharge .valve closed...... 40% ..... 60% ..... 150% .....
5 Inlet or discharge valve open........ ..... 40% ..... 100% 150% .....
Sintering-Inlet gates either open
or closed ..... ................. 40% ..... 100% 150% 25-60
Propeller-type Discharge open.. ..... 40% ..... 100% 150% 25
Pumps-Centrifugal (Horizontal) ...... ..... ..... ..... ..... 1
4 With discharge valve closed
High-and medium-speed......... 40% ..... 50-60% ..... 150i?1,
Low-speed .. . . . . . . . ........
....... 40%. ..... 70-100% ..... 150% .....
With discharge valve open.......... ..... 40% 100% 150%
-Centrifugal (Vertical)
4 With discharge vale closed
High-and mediurkr-speed......... 50% ..... 60-70% ..... 150'70
Low-speed ......................... 50% ..... 75-100% ..... 150'7/, .....
With discharge valve open.......... ..... 50% ..... 100% 150% .....
4 Adjustable-blade--Vertical......... 50% ..... 40% ..... 150% 1
Screw-type....... ..... ..... .....
1
Started dry...... i ................ 40% ..... 30% ..... 150%
Primed, dischargl open........... ..... 40% ..... 100% 150%
Axial-flow type.... I ................ ..... ..... ..... I
With discharge open .............. ..... 40% ..... 100% 150% .....
With discharge closed ............. ..... 40% ..... 200-300% Sante
2-CEMENT, ROCK PRODUCTS AND MINING MACHINERY
Grinding Mills
1 Attrition............ ............... 100% ..... 60% ..... 175% 12
Ball and Compeb
Rock and coal ....................... ..... 150% ..... 110% 150010 2
.......
Ore...... . . . .~ ................ ..... 175% ..... 110% 175c,,-, 2
Rod and tube mills-O4e ............... ..... 175% ..... 110% 175% 3
Crushers
B. and W............................... 200% ..... 100% ..... 25050 3
Bradley-Hercules ...................... 100% ..... 80-100% ..... 250% 3
Cone .................................. 100% ..... 100% ..... 250% 6
Gyratory ..............!................ 100% ..... 70-100% ..... 2505, 4
Jaw ................................... 100% ..... 70-100% ..... 25050 2
Roll ................................... 100% ..... 70-100% ..... 25050 3
Hammer mills .......................... 120% ..... 100% ..... 250% 15-40
Flotation machines.....: ................ 150-175% ..... 110% 17550 1
Fuller mills............ ................ ..... 125-150% ..... 110% 175%
-METAL ROLLING MILLS
Structural and rail-Roughing......... 40% ..... 30%
-Fiiishing......... 40% ..... 30%
Plate .................. i ............... 40% ..... 30% .....
Merchant trains ...................... 60% ..... 40% .....
Billet, skelp and sheet 1)ar-
(Continuous with layll~ shaft drive) .... 60% ..... 40%
Hot-stria. continuous. iinrlivirlnal dri?a
-6- ---e --- ..... I ............... "70 ..... 4u% 250-300%
Tube-piercing and. expatding.......... 60% ..... 40% ..... 300-350%
Tube-rolling (plug) ................ 60% ..... 40% ..... 250%
Tube-reeling. ............... 60% ..... 40% ..... 250%
Sheet and tin (cold-rollijng)............ ..... 200% ..... 150% 250%
REQUIREMENTS OF SYNCHRONOUS MOTOR APPLICATIONS
Locked-Rotor (Static) Pull-In Pull-Out Wk2"
Unloaded Loaded Unloaded Loaded Ratio
/ A .......... %
Brass and copper --Roughing........... 50% ..... 40% 250
ApprovfT . Release 1999/09/145PC1 -RDP83-00428800120 002-7
 ZO"us
Approved, For Release 1999/09/10 : CIA-RDP83-00423R0012T0045gpQ& No 9
MOTORS
TABLE 18-TYPICAL TORQUE REQUIREMENTS OF SYNCHRONOUS MOTOR APPLICATIONS-Continued
TYPICAL TORQUE REQUIREMENTS
In Percent of Full-Load Torque Max.
"L
d
APPLICATION
Unloaded
Loaded
Unloaded
Loaded
P-11-Out
oa
Wk2"
Ratio
4-PULP AND PAPER MACHINERY
(Approx.)
Beaters-Standard .....................
.....
125%
.....
100%
150%
5
5
-Breaker ...................... .
.....
125%
100%
200%
250%
30-100
1 Chippers (empty) ......................
60%
.....
50%
.....
150
Hydraupulpers ........................
.....
125%
125%
%
50
.....
1
Jordan (plug out) .....................
50%
.....
50%
.....
1
%
150%
5
Pulp grinders-Magazine type.........
. 50%
50%
.....
4
-3 or 4 Pochet type .......
40%
.....
30%
.....
150%
1
Screens-Centrifugal ..................
50%
.....
100%
150%
200
4
Vacuum pumps-(Hytor) ..............
.....
60%
.....
100%
%
5
30
1 Wood Hogs ............................
5-RECIPROCATING MACHINERY
60%
.....
60%
100%
22
%
Blowing Engines .......................
Compressors
40%
.....
50%
.....
150%
.....
10
Air and gas ............................
40%
.....
30%
.....
150%
Ammonia (discharge pressures 100 to
30%
150%
7
250 psi) ..............................
1 Ammonia boosters?
40%
.....
4
Freon ...............................
Carbon dioxide (with piston rod di-
ameter of 30% to 60% of piston
diameter) :
40%
.....
50%
.....
150%
5
10
1 Single-cylinder, double acting....
40-120%
.....
40%
.....
150%
-
4
7
Two-cylinder, double acting ......
40-90%
.....
40%
.....
150%
-
I
Pumps-Positive displacement...........
.....
.....
. ? ? ? ?
? ?
150
Started dry ............................
40%
.....
30%
40%
.....
%
150%
.....
.?
By-passed .............................
40%
.....
.....
100%
150%
Not by-passed (3-cylinder) .............
....
150%
.....
...
10
1 Vacuum pumps .......................
6-RUBBER MILLS
40%
.....
60%
.....
150%
Banbury mixers .......................
125%
100%
250%
1
..........................
Line shafts
125%
110%
225%
1
..
..........................
Plasticators
125%
100%
250%
1
.
Individual drive .......................
7-SAWMILLS
125%
100%
250%
1
Saws-Band mills ......................
80%
.....
40%
.....
250%
50
100
5
-Edger ...........................
40%
.....
30%
.....
2
%
10
-Gang' ..........................
60%
.....
30%
.....
200%
1
-Trimmer ..
40%
.....
30%
200%
30
1 Wood hogs ............................
8-MISCELLANEOUS
60%
.....
60%
100%
225%
' Blowers-Positive displacement,
40%
150%
8
rotating, cycloidal type ..............
6 Bowl mills-(coal pulverizer)
40%
, ,, ,,
(with common motor for pulverizer
125%
150%
? ? ? ? .
and exhaust fan) ....................
Compressors-Positive displacement,
rotating, sliding-vane type:
.....
150%
50
By-pass open..
60%
.....
30%
.....
1
%
150
.....
Inlet open, by-pass closed..........
.....
60%
...
100%
%
?...
15
5
1 Flour mill line shafts ..................
.....
175%
110%
150%
150
-
25
1 Gas cleaners-(Thiessen) ..............
40%
.....
60%
%
1 Vacuum pumps-(Ilytor)
150%
4
In other than paper mill service......
40%
.....
60%
1 These applications have high inertia, and the Wk2 of the load may require a motor design which cannot be determined from the
for ue requirements alone. For these applications the motor manufacturer should always be provided with the actual value of the Wk2
of the load.
2 a 4 The torque requirements may vary for the individual machine. The manufacturer should be consulted
5 May require higher torques under certain conditions; such as starting with cold air when rating is based upon normally warm air.
6 On some mills the exhaust fan may be separately driven and different torque values will apply; in either case the mill manufacturer
should a consulted. s s
At sng method.
"Te:??~ '"17 ?~"~ ,? ?;~ ..ailhnua~aihYwvaith alilieren~pR~9PS1litA>A'iSIP-
 YNCH b10p~0S p0ro ved For Release 1999/09/10 : Cl -RDP83-00423RO01200450002-7
CPYRGHT
MOTORS
Fig. H-57. This pedestal-bearing, 1000-hip, 720-rpm
synchronous motor has direct-connected exciter.
synchronous motor applications are given in Table 18.
Standard horsepower ratings, voltages and speeds of
synchronous motors are given in Tables 17A, B and C.
CONSTRUCTION OF SYNCHRONOUS MOTORS
Synchronous motors nay be divided into two general
classifications: (a) Hig -speed motors, operating at
speeds of 500 rpm or more, and (b) low-speed motors,
having speeds below 500 rpm.
High-Speed Motors
For high-speed synchronous-motors, the temperature
rise, based on an ambient temperature of 40 C, normal
conditions of ventilation' and an altitude o:' 3300 feet
(1000 ,meters) or less, will not exceed:
Unity power factor motors :
Armature.............40 C by thermometer
Field .............. ... 50 C by resistance
Leading power factor ;motors and all motors having
greater than normal torques:
Armature..............40 C by thermometer
Field ..............1...60 C by resistance
End-shield bearing construction is generally con-
sidered standard up to and including the following
ratings; these limitations' may be exceeded for certain
steady-load applications such as centrifugal com-
pressors, at speeds from 600 to 900 rpm:
Hp per Rpm
Rpm 1.0 Pf 0.8 Pf
500 to 900......... . 1.0 1.0
1200 ............. . 1.0 0.8
1800 .............. 1 .0.7 0.;i
Larger motors are generally furnished with a base
and two pedestal-type bearings. Provision :l'or stator
shift (to facilitate inspection and repair of windings) is
not standard but can be obtained at slight extra cost
Fig. H-58. Rotor for 900-hp, 0.B-pf, 900-rpm
synchronous motor shows collector ring details.
Lo i-Speed Motors
he temperature rise for standard :low-speed moto
is 5 C, that is, 10 C higher than for high-speed motor
However, the use of motors. with this temperature ri
is u wally confined to such applications as reciprocatin
co pressors and other non-overloading drives. Motoi
wit] i the same temperature rise as high-speed units ar
ava lable and essential for many types of application
sue]
L
end
as metal rolling mills, ball mills, etc.
)w-speed motors are available in engine-type
shield bearing, and pedestal-bearing construction
(Fi s. 54 to 62.) Engine-type units, which are furnishe
without shaft, base or bearings, are widely used fa
app ications such as reciprocating compressors. End
shied bearing construction is limited to some smalle
ratings. Pedestal-bearing construction, with base ar
ranted for stator shift optional, is available in al
larg r sizes. -
Ve ical Motors
V rtical construction is generally available for mos
rati gs and is widely used for pump drives.
in most ratings, except that it is usuall ALLIS-CHALMERS MFG. CO.
P y impractical Fi -59. Verticals o u o gently
in four anc~op veO'Fet- Release 1999/09/10 : fRD i Qo1I i Z rpm.
 CPYRGHT
Approved For Release 1999/09/10 : CIA-RDP83-00423R001200450002-7 H-31
ZTiml-FIKUNOUS
MOTORS
Fig. H-60. Enclosed synchronous motor rated 4500 hp
driving roughing stand in eastern steel mill.
Excitation
Field excitation should be provided from a source
that is not subject to circuit interruption. Direct-
connected exciters are preferable for high-speed
motors. For low-speed units, belted exciters or separate
motor-generator sets are recommended.
MOTOR PROTECTION
Classification of machines by types of mechanical
protection and methods of cooling will be found in the
definitions on pages 4 to 9. Accompanying illustrations
show some of the types applicable to synchronous
motors, and Table 19 gives a brief summary of such
features. Because synchronous motors are not built in
ratings as small as induction motors, some types (such
as totally-enclosed non-ventilated construction) are
not practical.
DATA ON COMPARISON
As a further aid to motor selection, the various
characteristics of synchronous and induction motors
have been summarized in Table 20.
Fig. H-61. Five 3500-hp, 11,200-volt, 257-rpm syn-
chronous motors driving paper mill pulp grinders.
Fig. H-62. Built for cement grinding mill use, this
synchronous motor is rated 1500 hp, 180 rpm.
TABLE 19-SUMMARY OF PROTECTION AND ENCLOSURES-SYNCHRONOUS MOTORS
Standard
Type of
Approximate
Temperature Rise
Approximate
Enclosure
Range of Sizes
Class A Insulation
Cost Increase
Application Information
Drip-proof
All ratings
Same as open motor
4 to 10%
Protection against dripping
liquids or falling particles.
15%
Protection against dripping
and splashing liquids.
Enclosed collector
All ratings
Same as open motor
4 to 30%
Used in both explosive and
rings
non-explosive at-
mospheres.
Totally-enclosed, High-speed 55 C 135% Used where abrasive dust,
fan-cooled only dirt, grit, or corrosive
Approved For Release 1999/09/10 : CIA-RDP83-00423R00''4=V2T7 ere for
Enclosed, forced- All ratings
ventilated
Enclosed-self- High-speed
ventilated only
 H-32 Approved For Release 1999/09/10 : Cl RDP83-00423R001,200450002-7
-
SYNCHRONOUS CPYRGHT
CONDENSERS
TABLE 20-COMPARISON OF GENE
AL CHARACTERISTICS OF
SYNCHRONOUS AND IND
UCTION MOTORS
Synchronous Motors
Induction Motors
Power Fact
r
Operates at unity (1.0) power factor with current in phase with Po
wer factor is always lagging due to magnetizing current re-
eed and large motors than
hi
h-s
h
hi
It i
voltage, or at leading power factor with current leading voltage. q
Hence, eminently suitable for power factor correction or im- in
g
p
er in
g
s
rements.
low-speed and smaller motors. It is highest at full load and
provement. de
reases with decreasing load:
Speed
The speed is an inverse function of the number of poles and B (
the power supply frequency, with which the motor is synchro- sy
l
h
d
h
cause of slip, standard motor speed is a few percent below
ichronous speed but remains constant under constant load
ue motors have higher slip. Motors
ecial hi
h-tor
S
diti
e co
ess t
ange
un
nized. The speed is constant and cannot be c
frequency is changed (except in the case of two-speed motors, ca
d
q
g
p
ons.
i
be designed as high-slip machines, with slip of 5 to 12 percent
i
di
e
which are available in the larger sizes only).
ze.
ng on s
pen
Wound-rotor motors with external adjustable resistance in
ro
or circuit can provide a wide range of ispeed.
Constructio
n
Salient poles, an amortisseur winding, and a field winding with T
lace the simpler cage rotor of the induc- a
re
a collector assembl
e polyphase squirrel-cage motor is the simplest in construction
for that reason it is the most reliable of all motors.
y
p
tion motor.
The wound-rotor type has a phase-wound rotor winding,
Motor is started with the field circuit closed through a re- co
sistor to prevent injury from high voltages due to transformer de
action. When excitation is removed, on shutting down the motor, re
lector rings and brush rigging, but these do not affect its
pendability. However, wound-rotor motors for plugging duty
uire special attention in design because of the double normal
the field is closed through a resistor to protect windings from vo
high discharge voltages. With present control, failure from these
ltage when plugging on full voltage.
sources seldom occurs.
Auxiliary App
ratus
Requires a separate exciter with shunt field rheostat, or a motor N
auxiliary apparatus is required for squirrel-cage motors.
field rheostat if excited froln a source common to several motors.
ound-rotor motors require secondary control.
Requires additional metering and field switches on the auxiliary
control.
Torques and Start
ng Kva
Starting, pull-up, pull-in, and pull-out torques ample for nearly
all types of constant-speed applications are obtainable. High- to
otor design classification determines variation of cage motor
rques from starting to breakdown. Locked-rotor (starting)
speed motor torques have been standardized by NEMA for cu
rrent for general-purpose ratings is in accordance with NEMA
common applications, but other values can also be obtained. st
ndards, and ranges from 400 to 650 percent for large ratings.
Locked-rotor (starting)! current is proportional to torque
requirements. It ranges from 250 percent for low-speed, low- re
Starting currents for wound-rotor motors depend on secondary
sistance and nature of the load. Starting current may be as
torque compressor motors .to 600 percent or more for high-speed, 1
as 25 percent for first step and usually will not exceed 250
high-torque motors. t
300 percent for full-load torque. Average accelerating current
fo
r average conditions is 125 percent.
Starting Met
hods
May be designed for starting (1) on full voltage, (2) on reduced
squirrel-cage motor may be started on reduced or full voltage.
voltage by means of an a@itotransformer or a reactor, or (3) by li
t the latter case a push-button-operated magnetic line con-
the part-winding method,] in which full voltage is applied suc- t a
ctor may be all that is needed.
cessively to each of several sections of the stator winding.
Manual or fully automatic magnetic controls are available
With present-day controls providing at least some automatic fo
r both the primary of cage and wound-rotor motors and the
functions, such as automatic field application, starting has a
condary of wound-rotor motors.
become nearly as simple as for cage motors. Some precautions
must, of course, be observd in selecting the control; for example,
a motor designed to start a machine wholly or partially unloaded
should not have a control 'arranged for automatic resynchroniza-
tion unless the driven maphine also has an automatic unloading
device. Controls are usually semi- or fully-automatic and provide
protection for various causes of failure.
Sizes and - Efl'i
encies
Not extensively used in ratings below 40 or 50 hp. In ratings
smaller than this, it is always a good idea to consider induction P
able 10 shows the efficiencies of standard induction motors.
olyphase induction motors can be built in any practical size
motors for high speeds and gearmotors for low ?.peeda. a
d speed. The only limit to size is the capacity of the au orting
and effect of lagging
current limitations
startin
r s
stem
For high speeds, weights and dimensions are comparable to p
those of squirrel-cage motors except as added to by the exciters. p
,
g
y
,
we
wer factor on the system.
For lower speeds, the synchronous type gradually becomes
smaller, than the induction type; this is particularly true at unity fo
For very large sizes at low speeds, such as large pump motors
r irrigation projects, the synchronous motor usually warrants
power factor. p
reference.
ties for unity ower-factor motors are somewhat
proxima s u
 CPYRGHT
Approved For Release 1999/09/10 : CIA-RDP83-00423R001200450002-7H-33
SYNCHRONOUS
c^nNn~r~ccne
rig. H-63. Air-cooled synchronous condenser with
wound-rotor induction starting motor.
SYNCHRONOUS CONDENSERS
A synchronous condenser is essentially a synchronous
motor running without load while connected to an
lectrical system. From an economic standpoint their
se is confined to the larger systems where correction
values are 1000 kva and over. These condensers can
lso be described as synchronous phase modifiers
nning without mechanical load, whose field excitation
an be varied so as to modify the power factor of the
ystem, or through such modification to serve as
oltage regulators. Fig. 63 shows a 12,500/6250-kva,
160-volt, 900-rpm air-cooled synchronous condenser
'th its wound-rotor starting motor.
Small condensers are mainly used for their corrective
fleet on system power factor, by supplying reactive
va to the system. The condenser may be controlled
Fig. H-64. Air-cooled synchronous condenser rated
25,000/12,500 kva is used in a southern steel plant.
to maintain a given system power factor, or it may be
operated at full leading kvar to supply all or part
of the system reactive kva. If the condenser is over-
excited it supplies leading kva, and if under-excited
it supplies lagging kva. In either case, system losses
are reduced, and capacity is released for useful work.
Synchronous condensers are also much used for
system voltage regulation. This function is especially
important on long high-voltage transmission systems
with high line charging capacity and loading. The
inertia of a synchronous condenser improves the speed
regulation and overall stability of the system. The
flywheel effect (Wk2) enables the condenser to act
momentarily as a generator to reduce system dis-
turbances caused by sudden load increases.
System improvement depends upon the inertia ratio
ABLE 21A-NEMA STANDARD KVA, SPEED AND VOLTAGES, AIR-COOLED SYNCHRONOUS CONDENSERS
Leading Lagging Speed Voltage Ratings
Kva Kva 60 Cycles 240 480 600 2400 4160 6900 *11,500 13,800
100
50
1200
x
x
x
x
x
200
100
1200
x
x
x
x
x
250
125
1200
x
x
x
x
x
300
150
1200
x
x
x
x
x
400
200
1200
x
x
x
x
x
500
250
1200
x
x
x
x
x
750
375
1200
x
x
x
x
1000
500
1200
x
x
x
x
x
1500
750
1200
x
x
x
x
x
2000
1000
900
x
x
x
x
x x
2500
1250
900
x
x
x
x
x x
3000
1500
900
x
x
x
x x
4000
2000
900
x
x
x
x x
5000
2500
900
x
x
x
x x
7500
3750
900
x
x
x
x x
10000
5000
900
x
x
x
x x
15000
7500
900
x
x x
20000
10000
720
x
x x
25000
12500
720
x x
30000
15000
720
x x
40000
20000
Inn
75000
37500
514
X
*This ratilfei-i4 v6d F eFW dl9 /1ot elA D,P88 OO 23 R001200450002-7
 H-34Approved For Release 1999/09/10 : CIA-RDP83-00423R001200d4gT-
CONDENSERS
Fig. H-65. Outdoor installation of 40,000/16,800-
kva, hydrogen-coaled synchronous condenser.
of the system and the condenser, which is influenced
by the size of the condenser. For example, the inertia
constant II ranges from 1.0 for a 5000-k,za condenser
to 2.0 for a 75,000-kv'a condenser, in the case of air-
cooled condensers rated at 13,800 volts.
Synchronous condensers are available in two forms,
air cooled, including indoor and outdoor types, and
hydrogen cooled. The! construction of the indoor air-
cooled condensers is wi~ry similar to that of an ordinary
synchronous motor. hey depend for cooling on the
free circulation of air i through and back of the core
and windings of the .'stator. Outdoor ai::?-cooled con-
densers may be either! self-ventilated, or they may be
totally enclosed, using a recirculating ventilating sys-
tem with coolers in the foundation. Ratings 3,000 kva
and larger are availably in the completely enclosed type.
Table 21A gives the NEMA ratings for air-cooled
synchronous condense.
Maj or operating dvantages of hydrogen-cooled
condensers can be summarized as follows. First, the
windage loss drops about 90 percent for average
operating conditions, with a consequent drop in leading
kva load losses. Second, the higher heat transfer
coefficient of hydrogetr makes for better output from
a given rating, and pe I rmits operating under overloads.
TABLE 21B-NEMA STANDARD KVA, SPEED AND
,VOLTAGES
HYDROGEN-COOLED ! SYNCHRONOUS CONDENSERS
Finally, maintenance is reduced because damage to
t insulation from corona-produced ozone is prac-
tically eliminated, and so is overhea-ting caused by the
accumulation of dirt in the ventilating passages.
Fig. 65 shows a hydrogen-cooled condenser installed
in a substation, and Table 21B gives the NEMA
r ings of such condensers.
Excitation
Exciters are usually of the direct connected type.
I cases where condensers are serving as voltage
regulators, the condensers, must be able to deliver
both lagging and leading kvar, possible variations
ranging from 40 percent lagging to 100 percent of the
le ding capacity.
An excitation system that acts accurately and
rapidly is necessary to obtain a smooth variation of
k ar over the entire operating ranges. The system
recommended for both large air-cooled condensers and
hydrogen-cooled condensers consists of the following
equipment:
1. Direct connected stabilized main exciter.
2. Standard motor-operated main exciter field rheo-
stat (for manual control in emergencies).
3. Motor driven Regulea, exciter set.
4. Static impedance type automatic voltage regu-
lating control, using :a saturated transformer and
a discriminating circuit.
Starting
There are several way$ available for starting syn-
onous condensers, but, reduced voltage starting
f om autotransformers is the one most commonly
u ed. Taps are provided for from approximately 20 to
3 percent of rated voltage, depending on the require-
ents of the system. As the larger condensers are
p ovided with high pressure lubrication, which reduces
tie breakaway torque, most machines can be started
ith no more than full lead line current when auto-
tfansformers are used.
If minimum starting kva is desirable for any reason,
direct connected wound-rotor induction motor can
used. The motor is designed with two poles less than
t fie condenser in order to accelerate the latter to
nchronous speed, and the condenser is synchronized
s
y
ith the power supply in the same manner as a syn-
+ronous generator. The motor and control are usually
ased on a starting time of about 2-1/2 minutes for
Leading
Lagging
Speed
Voltage Ratings
Kva
Kva
60 Cycles
4,160
6,900
*11,500
13,800 #
15,000
6,300
900
X
X
X
X
20,000
8,400
900
X
X
X
25,000
10,500
720
X
X
30,000
12,600
720
X
X
40,000
16,800
720
X
X
50
000
21
000
6 0
X
X
,
60,000
,
25,200
6D0
x
75,000
31,500
514
X
*This
i~ y~~.gg~
is not pf !k'M1'&t' W
Rel?I'e%te Ngwb `Th'b't: CIA
5000-kva condenser, and up to 5 minutes for the
rger sizes.
:ondensers as Power. Factor Correctors
The application and effect of a synchronous con-
enser for power factor correction can probably be
est shown by taking a concrete example. This case is
xRDPa3 Oe423RQ OO45oOO-7j improve
 Approved' For Release 1999/09/10: CIA-RDPO-d63W001200450002-7H-35
the power factor of a 300-kw system operating at
0.75 pf.
The first step is to express the components of the
system as shown in Fig. 66.
300 Kw B
Fig. H-66. Vector presentation of a system
delivering 300 kw at 0.75 power factor.
A 300 KW=ENERGY COMPONENT B
Fig. H-67. Determination of condenser output needed
to raise power factor from 0.75 to 0.9.
H
U.
W
SYNCHRONOUS
kw
Using the equation pf = kva and solving for kva
300
we have 0.75 or 400 kva.
In Fig. 66 line AB equals 300 kw. Since kvar is
always at right angles to kw, the perpendicular BH
is erected at B on AB. With A as a center, and a
radius equal to 400 kva an are is described that cuts
BII at C.
The triangle ABC shows graphically the total kva
(AC) of the generator, its energy component (AB) and
the wattless component (BC), which is 264.5 kvar. The
triangle also shows the phase relation between AB and
AC : angle A. This angle need not be determined be-
cause its cosine (AB) equals the power factor, 0.75.
As the next step, using the same equation pf = k a
and assuming that a power factor of 0.9 is desired,
solving for kva shows that the system must be altered
(kva \
so that it delivers only 333.3 kva = 300
0 9 J
Then using the triangle already developed, with A as
a center, and 333.3 kva as a radius an are is described
that cuts BC at E (Fig. 67). By scale, or otherwise,
BE = 145.2 kvar, and EC = 119.3 kvar.
Therefore, a synchronous condenser with an output
of 119.3 kva at zero pf leading would correct the system
power factor to 0.9.
To take another phase of the problem, assume that
it is desired to find out what the effect would be of
adding a 150-kva condenser; 150 kvar is laid off on
line CB. The value of AK can be found by scale
measurement, or by solving the triangle; ABK, to be
321.1 kvar. (Fig. 68.)
The resultant power factor is 3200 = 0.93.4.
DIRECT-CURRENT MOTORS
Direct-current motors are used for applications that
require continuous operation under fairly constant
load (such as fans, blowers, line shafting) in plants
having direct-current rather than alternating-current
power service. In addition, they are used for applica-
tions such as machine tools when fine speed adjustment
and other characteristics of dc motors are so necessary
that the cost of conversion equipment is warranted
when the source of electrical power supplies alternating
current.
Direct-current motors are divided into three classes:
series, shunt and compound wound. These terms refer
to the relationship of the connections between the
armature and fields. Each type is explained briefly
below, while Table 22 on page 36 provides a ready
ti
li
ti
d
h
f
h
ca
ons an
opera
ng c
ar-
e app
t
H-68. Effect of adding a 150-kva synchronous comparison o
Apprm nF*rbftJG0l0.1999/09/10 : CIAE b 83-00423 R001200450002-7
 H-36Approved For Release 1999/09/10 : CIAO-RDP83-00423 R001200450d92-- GHT
DC MOTORS '
TABLE 22-COMPARISON OF GENERAL CHARACTERISTICS OF DC MOTORS
Series Motors Shunt Moto s
Applieatio s
Where speed can be regulated and where Wt-ere starting conditions are not severe Required where high starting torque
high starting torque is necessary. Car and where constant or adjustable speed combined with fairly constant speed is
retarding, traction, car dampers, hoists, is :necessary. Metal wor mg machines, necessary. Conveyors, plunger pumps,
gates, etc. elegy ators, centrifugal pu s, line shafts, bending rolls, punch presses, elevators
High. Varies as square of voltage. Limited
by commutation and heating.
High. Limited by comin.utation and
heating.
Zero to maximum, according to load
and control.
Speed varies inversely with the load.
Races on light loads and full voltage.
Good. Constant field, va:
voltage applied to armat
High. Limited by
heating.
es directly as
.re.
Speed Cent
Any range desired, actor
mol;or and system.
TABLE 23A-STANDARD HORSEPOWER RATINGS
-DC MOTORS
GENERAL-PURPOSE MOTORS: 1/2; 3/4, 1, 1-1/2, 2, 3,
5, 7-1/2,10,15, 20, 25, 30, 40, 50, 60, 75, 100, 125, 150, 200.
LARGE MOTORS: 250, i 300, 350, 400, 500, f'00, 700, 800,
900, 1000, 1250, 1500, 71750, 2000, 2250, 2500, 3000, 3500,
4000, 4500, 5000, 5500, 4000, 7000, 8000.
TABLE 23B-STANDARD VOLTAGES-DC: MOTORS
Voltage
Approximate Hp Range
115
1/2
- 30
230
1/2
- 200
250
250
- 1D00
600
250
- 8D00
TABLE 23C-STANDARD
Speed in Rpm
SPEEDS--DC MOTORS
Approximate Hp Range
3500
1-1/2
- 40
1750
1
- :100
1150
3/4,
- 800
850
1/2
- 1't50
690
1/2
- 2250
575
3/4
- 2500
500
3/4
- 3000
450
1
- 3500
400
1
- 4000
350
1
- 4500
300
10
- 5000
250
20
- 5000
225*
250
- 5000
200
75
- 5000
175*
250
- 6000
150
75
- 7000
140**
7000
- 8000
130**
7000
- 8000
125*
250
- 6000
120**
7000
- 8000
110*
250
- 8000
100
75
- 8000
90
500
- 8000
80
600
-
8000
70
700
- 8000
65
800
- 8000
60
800
8000
55
900
- 8000
50
1000
-
8000
Higher than for shunt motors, according
to amount of compounding.
High. Limited by commutation and
heating.
Any range desired, according to type of
motor and control.
Drops 7 to 25 percent from no load to
full load, according to type of motor
and control.
he armature and fields of the series motor are
co netted in series (Fig. 69), and the speed of the
motor varies inversely with the load; that is, the speed
increases as the load decreases. This is due to the
change in field strength with changes of current in the
fie caused by the load on the motor.
or this reason, a series motor should never be
applied to a drive which can become unloaded. In
ge eral, a series motor should be direct-coupled to its
loa 1, for with full voltage 'applied and without load,
its speed increases to the destruction point.
odifications of the series motor include a small
shunt winding of sufficient strength to prevent the
mo or reaching dangerous speed but not materially
ch nging its series characteristic.
he armature and fields of the shunt motor are
co'
spe
to
d
ng to type of
ected in "shunt" or parallel (F'ig. 70), and the
d of the motor is practically constant. This is clue
he constant strength of the field.
odifications of the shunt motor include a small
seri~s winding of sufficient strength to assure a drooping
shu
con
d characteristic over a field weakening range.
his type of motor is commonly called a stabilized
t motor. Connections are the same as shown for
pound-wound motors.
COMPOUND MOTORS
The compound-wound motor has both series and
shunt
windings (Fig. 71), resulting in the characteristics
of
both series and shunt motors. That is, it provides
*These s cods standard f r motors larger than 200 h on1 ., hig starting torque and constant speed. The exact
**These roved Fou Release 1n989A9/~10 : ({. aR &3
-004a23d 0> 12~4~5Q0Q2* r will
Speed Regula ion
Varies with size and spec range from 2
to 75 percent. Close regula ion obtainable
with special control.
 CPYRGHT
Approved For Release 1999/09/10 : CIA-RDP83-00423R0012004500Q 7MOroRs
Fig. H-72. Armature for small dc motor.
Fig. H-69. Field and armature relationship in a
series-wound dc motor.
Fig. H-70. Field and armature relationship in'Ja
shunt-wound dc motor.
Fig. H-73. Field yoke ready for insertion of special
compensating winding in pole faces.
Application Information
Protection against dripping
liquids or falling particles.
Protection against metal chips in
machine shops, etc.
Combines above features.
Protection against dripping and
splashing liquids.
Same as totally-enclosed.
Same as totally-enclosed.
Used where abrasive dust, dirt,
grit, or corrosive fumes are too
severe for open motors. Metal-
working plants, foundries, ma-
Fig. H-71. Field and armature relationship in a
compound-wound dc motor.
depend upon the relationship of the series and shunt
fields.
Standard horsepower ratings, voltages and speeds of
direct-current motors are given in Table 23.
MOTOR PROTECTION
Classification of machines by types of mechanical
protection and methods of cooling will be found in the
definitions on page 4. Illustrations on pages 5 to 9 show
the construction employed for various types, and
Table 24 gives a brief summary of such features. This
table shows (a) the approximate range of ratings in
which each type is built, (b) the maximum temperature
rise for Class A insulated machines, (c) the approximate
increase in cost over the standard open type, and
(d) application suggestions.
Type of
Approximate
Temperature
Approximate
Enclosure
Range of Sizes
Rise
Cost Increase
Drip-proof
All sizes
50 C
2%
40 C
10 to 17%
All sizes
50 C
5%
40 C
12 to 20%
Drip-proof,
All sizes
55 C
5%
fully protected
40 C
12 to 20%
Splash-proof
All sizes
50 C
8 to 15%
40 C
16 to 27%
Separately ventilated
All sizes
40 C
9 to 15%
Self-ventilated
All sizes
40 C
15 to 30%
Totally-enclosed:
Non-ventilated
1/2 to 15 hp
55 C
35 to 110%
Fan-cooled
1 to 100 hp
55 C
35 to 90%
Approved For Release 1999/09/10 : CIA-RDP83-00423RObl OF45DD02-7
 H-38
CPYRGHT:
A Dproved For Release 1999/09/10 : Cl
DC MOTO
-RDP83-004238001200450002-7
EFFECTS OF VOLTAGE VARIATION
Direct-current systems, like alternating-current sys-
tems, are subject to variations in voltage above or
below the rated value.: Standard-voltage motors will
operate successfully, but not necessarily in accordance
with standard guarantees, at voltages 10 percent above
or below the nameplate stamping.
Table 25 shows the general effects of operating shunt
and compound-wound motors at voltages above and
below normal.
ADJUSTABLE-SPEED CONTROL
In many plant operations adjustable-speed control is
essential to production efficiency and product quality.
In metal-working shops rubber mills, paper mills, and
textile finishing plants,; for example, the advantages
of having operating speeds that can be exactly ad-
justed to suit the dimensions, materials and. conditions
that affect quantity and quality of production can
hardly be overemphasized.
Where do power is available, obtaining adjustable
speed presents few difpiQulties, for do motors have the
characteristics most desirable for adjustable-speed
service. And a wide ariety of control equipment
makes it possible to select a suitable drive for prac-
tically any application.
Where only the more (widely used 3-phase ac power
is available adjustable-speed operation is not as readily
obtainable, but neither xs it impossible of attainment.
In either case, it is inrportant not to overlook the
fact that selection of a satisfactory method of speed
control, when required, can quickly pay for itself with
even a slight increase it daily output. Following is a
summary of the principal methods available for plants
having direct current and for those limited to alter-
nating current :
Fig[ H-74. Test assembly: of shunt-field controlled
wi -drawing machinery with 30/40-hp dc motors.
Direct-Current Plants
Shunt-field control.
Armature control.
Combined shunt-field: and armature control.
Variable-voltage control.
Al ernating-Current Plants
1. Wound-rotor induction motors.
. Multi-speed induction motors.
. Use of conversion equipment to provide de power.
Page 11-48.
Variable-pitch V-belt drives.
Magnetic or hydraulic couplings.
SHUNT-FIELD CONTROL
ariation in the speed of a shunt-wound or stabilized
shut-wound motor is obtained by inserting an ad-
justable resistor in the shunt-field circuit of the motor.
This provides adjustable-speed control because the
sped of the motor varies inversely with the strength
TABLE 25-EFFECTS OF VOLTAGE VAtIATION ON DC MOTORS
STANDARD SHUNT OTORS
Voltage
Variation
from
Normal Full Load 75% Load 50% Load
10% low Slightly lower No change Slightly higher
10% high Slightly higher No change Slightly lower
20% high Slightly higher No change Slightly lower
Percent Starting
Full Maximum
Load Full Load Running
Speed Current Torque
-5% +11-1/2% -16%
Maximum
Overload Temperature Rise,
Capacity Full Load
-16% Main field higher.
Commutator, field
and armature higher.
+15% Main field higher.
Commutator, field
and armature lower.
+30% Main field higher.
STANDARD COMPOUND-WOUND MOTORS
10% low Slightly lower; No change Slightly higher -6% I+11-1/2% -16% -16%
Commutator, field
and armature lower.
Main field lower.
Commutator, field
and armature higher.
10% high Slightly higher No change Slightly lower +6% -8-1/2% +15% +15% Main field higher.
Commutator, field
and armature lower.
20% high Slightly higher No change Slightly lower +12% -17% +30% +30% Main field higher.
Approved For Release 1999/09/10: CI -RDP83-00423R00120&UWifwA sower.
 CPYRGHT H-39
Approved, For Release 1999/09/10 : CIA-RDP83-00423ROO12O 9 Q LL SPEED
Fig. H-75. Variable-voltage and shunt-field control
are used for 600-hp, flywheel-type tube-mill motor.
of the fields. That is, the stronger the fields the lower
the speed; as the fields are weakened the speed in-
creases.
As the strength of the field is decreased, the torque
delivered by the motor also decreases; but since the
speed increases proportionately, the horsepower output
of the motor would be expected to remain constant.
However, due to increased ventilation at the higher
speeds, the horsepower capacity will actually be
slightly more than at the low speeds. This increase in
capacity can be used to advantage in providing an
economical drive.
The efficiency is relatively high at all speeds, and
the speed regulation from no-load to full-load can be
held within close limits. Motors with speed ranges of
4 to 1 are regularly supplied, and ranges of 6 to 1 are
sometimes practicable. The limitation to the speed
increase is the ability of the motor to carry the load
at the high speeds without sparking.
Compound-wound motors are sometimes used for
this method of speed adjustment, but the results are
not as satisfactory as with shunt or stabilized shunt-
wound motors. When the compound-wound motor has
its shunt fields weakened to too great an extent, it more
nearly approaches the characteristics of the series
motor-with the inherently poor speed regulation of
the series type.
ARMATURE CONTROL
Speed control using this method is obtained by
inserting a variable resistor in the armature circuit.
A shunt-wound motor is generally used. Speeds obtained
are below the normal motor speed, and the horsepower
output decreases directly with the speed. Armature
control is not usually employed for speed reductions
greater than 50 percent below normal: The efficiency of
the motor is reduced at the low speeds, and the speed
regulation, while satisfactory at the high speeds,
becomes poor as the speed decreases.
Nevertheless, the armature control method can be
Fig. H-76. Planer drive with 30-hp motor also has
combined variable-voltage and shunt-field control.
is so small that the low efficiency is not important, and
where a constant-horsepower output with close speed
regulation is not required. This system is frequently
used for fans and blowers, especially where the unit
operates at the low speeds for only a few hours a day.
By using a compound-wound motor it is possible to
obtain better starting characteristics for heavy loads
than with the shunt-wound motor; but because ` 'of
poor speed regulation, adjustment should be limited
to about 30 percent below normal.
Series-wound motors are occasionally used with
armature control for adjustable-speed service. Of
course, with this type of motor, increased load will
result in decreased speed, and decreased load will
result in increased speed. Their principal use is for
hoisting machinery in which some load is always
present. While the load is being lifted, the speed can
be adjusted fairly closely by regulating the amount of
resistance introduced into the circuit. Series motors are
useful where heavy starting loads are involved, since
the torque developed is, up to the stalling point of the
motor, determined by the load imposed.
COMBINED SHUNT-FIELD AND ARMATURE CONTROL
Combined shunt-field and armature control provides
a wider speed range than can be obtained by either
system alone. The speed is reduced below normal by
armature control and increased above normal by field
control.
Such a combination is used on printing presses, fans,
blowers, and similar applications. That is, it is used
where low speeds without close regulation are required
at times but with most of the operation above normal,
since the efficiency by field control is much better than
by armature control.
VARIABLE-VOLTAGE CONTROL
As the name implies, this method makes use of the
fact that the speed of the motor will vary in direct
proportion to the voltage of the current supplied to the
used f(AlDJb1 60d*W Fit o44)W Pt CIA PYP$T b 42T O M64'dt}0-l' where a
 IIII-e
ADuSUffay For Release 1999/09/10 : CIAO-RDP83-00423R001200450&e2YI GHT
smooth, gradual increase in speed is needed-over a
wider range than cart usually be obtained by other
methods.
In its simplest fora this system consists of (a) an
adjustable-speed dc motor, (b) a motor-generator set
to supply the power-,t variable voltage---to drive the
motor, and (c) a constant-potential sou:?ce of direct
current for exciting the fields of both the adjustable-
speed motor and the motor-generator set generator.
The armature of the generator is connected elec-
trically to the armature of the adjustable-speed motor.
Since the motor has its fields separately excited at a
permanent flux value, its speed will be in direct propor-
tion to the voltage stiipplied by the generator. The
torque imparted to the motor armature will remain
practically constant atall times. Thus the horsepower
output of the motor ill vary with the r.'iotor speed,
being greatest at the highest speed.
Speed control is just as simple as for shunt-field
control. It is accomplis#ied with a field rheostat in the
shunt field of the generator. Speeds of :10 to 1 are
frequently used, while 4 15 to 1 or even 20 to 1 range
may be obtained under favorable circumstances.
Speed regulation is at its best at the higher speeds;
at the lowest speeds it is close enough to be satisfactory
for most applications. The efficiency at high speed is
not as high as with other forms of control; a.t low speed
the efficiency is higher than with armature control but
lower than with shunt-field control. It is more economi-
cal in the use of power than either of the other two
methods.
TABLE 26.
SUMMARY OF PRINCIPAL M
M
th
d
Range of
Speed
Speed
e
o
Hp Ratings
Range
Regulation
Shunt-field
t
l
1/2hp
4 to 1,
Can be held
con
ro
and larger
sometimes
within close
6 to 1
limits.
Ar comature
1/21hp
2 to 1
Satisfactory al
and I#rger
high speeds,
not so good
at low speed
Motor field weakening; above base speed may be
employed along with variable-voltage control to pro-
vide a very wide speed range of do motor operation.
The variable-voltage system can, be used in both
a and dc plants. When used on alternating current,
the generator is usually driven by a squirrel-cage
induction motor; larger sets may be driven by syn-
chronous motors, and flywheel sets for reversing hoist
o metal rolling mill motors are driven by wound-
ro or motors. Excitation is usually provided by an
exciter direct-connected to the motor-generator set.
For the smaller horsepower drives, the last few
years have seen increasing use of electronic tubes to
rectify alternating current to direct current to power
d motors. See Section Q.. A wide motor speed range
may be obtained by varying the output voltage of the
power tubes. Excitation for the field of the motor is
a ho obtained from electronic tubes. In addition, by
su tably controlling the power tube output, motor IR
drop compensation may be obtained, providing very
god motor speed regulation even at very low speeds.
T le 26 gives a summary of the principal methods of
sp ed control.
METHODS DISCUSSED ELSEWHERE
he use of wound-rotor and multi-speed squirrel-cage
motors is discussed in the section on induction motors
(se pages 20 and 21, respectively). Equipment for
converting alternating current to direct current is
discussed in various sections of this book, including
the preceding section on variable-voltage control and
a subsequent section on motor-generator sets.
THODS OF SPEED CONTROL
Torque
Characteristics Remarks
Reduction of Most frequently used of all
torque as speed for dc adjustable-speed
increases. motors.
Horsepower de- Used principally for smaller
creases directly motors and where oper-
with speed. ation at low speeds is for
only a few hours a day.
Series motors used for
hoist drives.
ombined
shunt-field
1/2
and 1 rger
6 to 1
See above
See above
andarmature
listings.
listings.
control
Variable
l
1 lip
10 to 1,
Good at high
To
i
vo
tage
and larger
sometimes;
speeds, satis
rque rema
ns
constant.
15 or 20
factory at
to I
low speeds.
Wound-rotor
3/4 hp
2 to 1
Poor at reduce
Ho
d
motor
and larger
speeds.
rsepower
e-
creases with
i
speed.
1/2 lip
d l
2to 1,
Same as single.
Constant horse-
an
ager
3 to 1,
speed motor.
power, constant
or
Approved For Rele`aae 1999/09/10 : Cl
-RDP torque s4'vbt?O -7
Used where most operation
will be above normal
speed.
Requires separate motor-
! generator set.
Iligh starting torques; low
efficiencies.
Gives 2, 3, or 4 fixed speeds,
except when wound-rotor
 Approved For Release 1999/09/10 :CIA-RDP0 0012004500c9 - H-41
RATORS
GENERAL
Fig. H-77. Geared turbine-driven, 250-kw, 312-kva,
1200-rpm synchronous generators.
GENERATORS
The rapid growth of power-generating central sta-
tions and power-transmission systems has provided
industry with an abundant supply of electric power.
Development of water power, which accounts for
about 25 percent of the total, and refinements in the
design of steam-generating equipment have resulted in
the production of power at remarkably low cost.
Since utilities generate power with large and con-
sequently more efficient units, purchased power is
economically satisfactory for most industrial purposes.
However, there are cases where industry finds it
desirable to generate its own power: Where steam is
essential in manufacturing processes, it may be ad-
vantageous to install a non-condensing turbine-genera-
tor unit. In some locations, the advantages of large-scale
generation may be unobtainable; on shipboard it is
obviously impossible. If continuous operation is impera-
tive, it may be essential to provide standby power.
The advantages and disadvantages must be carefully
weighed, both from the standpoint of cost and manu-
facturing efficiency. If the decision favors power
generation, the selection must be made between
alternating current and direct current.
There are fields where only direct current will meet
the requirements, such as extra-wide speed range or
severe accelerating or reversing duty. For most ap-
plications, alternating current is satisfactory, since
suitable performance can usually be obtained with ac
motors and control, and there are many fields in which
alternating current is the only suitable choice.
ALTERNATING-CURRENT (SYNCHRONOUS)
GENERATORS
Synchronous generators are generally divided into
three groups, as follows:
Fig. H-78. Horizontal hydraulic-turbine driven,
3000-kva, 720-rpm synchronous generator.
2. High-speed generators, operating at 500 to
1800 rpm.
3. Low-speed generators, operating at less than
500 rpm.
As the problems involved in the selection and
operation of two-pole turbine-generators are so closely
related to those of the steam turbine, it has been
considered advisable not to attempt to describe this
class of equipment here. The following information
applies to Groups 2 and 3 only.
AC Generator Ratings
Alternating-current generators are rated at the load
they are capable of carrying continuously without
exceeding their temperature guarantees. Each rating
is expressed in kilovolt-amperes available at the
terminals at 0.8 power factor. Standard ratings for
0.8 pf lagging generators are shown in Table 27A, B
and C.
1. Two-pole, 3600-rpm (60-cycle) generators direct- Fig. H-79. Diesel-driven engine-type, 1875-kw,
drpe bV6&"PR,6Iease 1999/09/10 : CIA-R f$l9'- d` $PUbSP'2d bo7- ator.
 H-42 Approved For Release 1999/09/10 : Cl
AC GENERATORS
TABLE 27A-STANDARD KILOWATT RATINGS-
SYNCHRONOUS GENERATOR;
The following are NEM4. listings for 60, 50 and 25-cycle, 0.8
power factor lagging, polyphase synchronous generators ex-
clusive of turbine-driven, water-wheel and inductor synchronous
generators.
Kva
Kw
*a
Kw
Kva
Kw
1.25
1
50
200
4375
3500
2.5
2
12
250
5000
4000
3.75
3
75
300
5625
4500
6.25
5
38
350
6250
5000
9.4
7.5
$00
400
7500
6000
12.5
10
625
500
8750
7000
18.7
15
750
600
10000
8000
25
20
$75
700
12500
10000
31.3
25
1 00
800
15625
12500
37.5
30
11;25
900
18750
15000
50
40
1450
1000
25000
20000
62.5
50
1163
1250
31250
25000
75*
60*
1875
1500
37500
30000
93.8
75
2188
1750
43750
35000
125
100
2100
2000
50000
40000
156
125
2 12
2250
62500
50000
187
150
3
25
2500
75000
60000
219
175
.
3150
3000
*The standard speeds for
inclusive.
For standard generators, the temperature rise, based
on an ambient temperature of 40 C, normal conditions
of ventilation, and an altlitude of 3300 feet (1000 meters)
or less, will not exceed :
Armature (stator).'. .... 50 C by thermometer, or
60 C by temperature
detector
Field (rotor) ............50 C by thermometer, or
60 C by resistance
AC Generator Construct'on
High-speed generato1s are usually available with
shaft and bearings for coupled duty. End-shield con-
struction is, in general, standard for the smaller sizes,
while pedestal-bearing construction is available for the
larger ratings. Engine-type.and belt-driven generators
are also available in the high-speed range.
For speeds below 50 rpm, engine-type generators
are commonly furnished (Fig. 80); that is, the shaft,
bearings and base are supplied by the engine builder.
Sole plates for the staor are, however, included as
standard equipment ith engine-type generators.
When required, two-baring coupled-type or three-
bearing belted-type generators can be furnished in the
low-speed ratings.
Generator field rheostats are normally furnished with
ac generators, but may be omitted under tic following
circumstances :
1. When the generator is excited from its own
individual exciter and the exciter is used for no
other purpose. (Fot operation without a generator
field rheostat, the qxciter must be of the stabilized
type, stable down; to the voltage corresponding
CPYRGHT
RDP83-00423 R001200450002-7
TABLE 27B-STANDARD VOLTAGES-
SYNCHRONOUS; GENERATORS
Voltage Approximate Kva Range---0.8 Pf
120 Up to 93.8
240 Up to 875
480, 600 6.3 - 1875
2400, 2500 25 and larger
4160 62.5 and larger
TOTE: Higher voltages (4330, 6900, 11,500, and 13,800
,
ts) are available, at additional cost, for large generators.
4BLE 27C-STANDARD; SPEEDS--SYNCHRONOUS
GENERATORS
Speed in Rpm
(60 Cycles)
Number of
Poles
Approximate Kva
Range -- 0.8 Pf
1800
4
Up to 625
1200
6
12.5 - 3125
900
8
31.3--5000
720
10
31.3-
600
12
31.3-
514
14
31.3 -
450
16
125
400
18
125
360
20
125
327
22
125
300
24
125
277
26
125
257
28
125
240
30
125
225
32
187
200
36
187
180
40
187
164
44
187
150
48
250
138
52
312
129
56
438
120
60
438
109
66
438
100
72
438
When the exciter will never be paralleled with
other exciters.
When certain forms of automatic voltage regula-
tors (which have rheostats or their equivalent
contained in the mechanism) are used.
to the field voltage required by the generator Fig H-80. Stator and rotor assemblies for a large
at_nAo#rbved For Release 1999/09/10: CI-RD 0Q4%R8Cha0 0042-7
 CPYRGHT
Approved For Release 1999/09/10 : CIA-RDP83-00423R001200450002-7H-43
AC GENERATORS
Fig. H-81. V-belt drive is used for exciter
economy on this low-speed ac generator.
The recommended practice is to include a generator
field rheostat, as the same refinement of voltage control
cannot be expected when the rheostat is omitted.
Exciters
Direct-connected exciters (Fig. 82) are preferable for
high-speed generators. Standard construction provides
for overhanging the exciter armature on the generator
shaft, with the field frame supported from the generator
end-shield or by an extension of the generator base.
Occasionally, two-bearing coupled-type exciters are
used.
Belted exciters, either V-belt or flat-belt driven, are
commonly used for the low-speed generators.
Parallel Operation
Successful parallel operation of ac generators driven
by steam or internal-combustion engines is dependent
upon the following:
1. Laminated-pole generators must be equipped
with damper windings when one of the prime
movers is an internal-combustion engine.
2. The speed characteristics of the prime movers
must be similar so that there will be a proper
division of load.
3. The governors of the prime movers must be
designed and adjusted to prevent hunting, with
interchange of power between the generators.
4. The value of the flywheel effect of the units in
parallel must be such that: (a) The varying
turning effort of the engine does not produce
more than 0.5 to 0.6 percent variation in speed
when the unit is operating alone. (b) The natural
frequencies of oscillation of the units are far
enough from the impulse frequencies so that
objectionable oscillations are not set up; usually
20 percent difference between impulse and
natArpJJrbVMigsse 1999/09/10
Fig. H-82. Small, high-speed synchronous generator
has direct-connected overhung exciter.
Impulse frequencies are: four-cycle engines-
one-half the speed of the engine and any multiple
thereof; two-cycle engines-the speed of the
engine and any multiple thereof.
For any given unit the natural frequency, at
which the generator rotor tends to oscillate, can
be changed by changing the flywheel effect.
Successful parallel operation calls for cooperation
between the engine and generator builders. The genera-
tor manufacturer can be of assistance by furnishing
technical information and by providing the requisite
flywheel effect in the generator.
Voltage Regulation
When an ac generator is furnishing power to a
steady load, both its speed and voltage remain constant.
Any sudden increase in load, such as might be caused
by starting a large motor, will affect both voltage and
speed.
The effect on the voltage is an instantaneous drop,
the extent of which depends on the magnitude of the
load change and the inherent characteristics of the
generator. After this instantaneous drop, a further
and more gradual decrease takes place before the
automatic voltage regulator can act to bring back
normal voltage by strengthening the generator field.
The subsequent rise in voltage is more gradual than
the drop, due to the reactance of the field windings
(magnetic inertia) of the exciter and main generator
rather than the time required for the voltage regulator
to act.
Should there be a sudden reduction instead of an
increase in load, there will be a sudden rise in voltage
followed by a gradual decrease to normal.
Such voltage fluctuations due to change of load are
C NAARb 3 OO423R?dV200 a7 present
 H-44 Approved or Release 1999/09/10 : CIA-RDP83-00423 R001200450002PYRGHT
AC GENERATORS II
that can prevent them-The degree of voltage uc ua- 25 percent were Better regu
tion will depend on: other reasons.
1. Kva capacity and, pf rating of the generator.
2. Inherent regulation of the generator. 5e ection of AC Generators
3. Kva and pf of the load change. he intelligent selection of ac generating equipment
4. Kva and pf of the load the generator is carrying to meet the needs of a particular installation fully and
economically requires mature engineering judgment
when the load change occurs. based on experience and on complete information about
If the above data is available, it is possible to calcu- the amount and character of the loads to be carried.
late the amount of ti4 resulting voltage change and ncluded in this information should be: amount of
thereby determine the, effect on the quality of the lig ting load; amount of power load and its average
service. power factor; number and size of motors, with details
In general, voltage disturbances are caused by two of control showing whether across-the-line or reduced-
classes of applications: vo tage starting is used and. the frequency of starting;
1. Starting and stopping of motors or other power de ree of voltage fluctuation that can be tolerated;
loads, particularly: told curve showing the variation of total load through-
a) Alternating-current elevator motors-for both ou the day and night.
passenger and freight service. 3ecause of the limited capacity of smaller systems
b) Pump and cgmpressor motors started and co pared to large central-station systems, the question
stopped frequently by automatic starters con- of voltage fluctuation is of great importance. If con-
trolled by pressure or liquid levels. sic oration of the class of service indicates that the
c) Crane and hoist motors. pr bable voltage fluctuations would be objectionable,
d) Drives requiring frequent reversal of motors. co sideration must be given. to:
e) Motors using; full-voltage starting-particu- Reduction of motor starting currents through the
larly high-speed motors. use of reduced-voltage starting of squirrel-cage
f) Induction or electric-arc furnaces. motors, or even further by the use of wound-
rotor motors.
g) Spot welders. . Use of flywheel m-g sets for part of the load-for
2. Variation in motor loads, such as: cushioning the frequent starting of elevator
a) Air or refrigeration compressors with auto- motors, for example.
matic loading 4nd unloading devices. Use of separate generators for lighting and for
b) Punch pressed and similar machines with power.
intermittent loads. L. Use of generators with better than standard
c) Compressors with insufficient flywheel effect. regulation.
Voltage fluctuations must be given part:.cular atten-
tion in the case of hotels, apartments, clubs, schools, of the number and size of units which will provide
libraries, office buildings, hospitals, and other places efficient operation at times of light load, to provide
where reading or close work calls for steady lighting. sufficient standby capacity for emergencies, and to allow
Even a 2-volt drop will cause an observable flicker in periodic inspection and cleaning.
a 120-volt lamp, and the degree of flicker will increase When full data is not already available, it can fre-
with greater voltage drop. Of course, how objectionable q ntly be obtained from'a study of monthly power
the flicker is depends to some extent on its frequency.
bi
In considering the degree to which voltags fluctuation Is. Demand charges will give the peaks to supplement
may be tolerated, there are several classes of equipment a rage load data, and in many cases power factor
data will also be available. 'T'hese figures will, however,
other than lamps which require unusually good voltage
us ally have to be supplemented by readings from
regulation:
re ording or indicating wattmeters and ammeters.
X-ray equipment. If such readings cannot be obtained, the various
Motion-picture sound projectors. motor loads may be tabulated, and the lighting load
Teletype machines, may be estimated from the number and wattage of
Continuous-tube seam welders. lamps and their usual hours of use.
Magnetic brakes on' some elevator motors may set In plants not already electrified, the required data
if the voltage drops more than 10 or 15 percent. In ca be obtained to some extent from engine indicator
general, motor control requires a voltage drop of ca ds, by comparison with similar plants which have
40 to 60 percent to shut down motors under their ben electrified, and from figures obtainable from the
n s
 Approved For Release 1999/09/10: CIA-RDP83-00 11-200450002-7 H-45
AC GENERATORS
TABLE 28-INFORMATION REQUIRED FOR SELECTING
AC GENERATORS
GENERAL
Type of generator (engine, coupled, belted) ................
Quantity.......... To be driven by ......................
Kva.... Pf.... IRpm.... Phase.... Cycles.... Voltage....
Ambient temperature......... C Temperature rise .......... C
Class of insulation: Armature (stator) ...... Field (rotor) ......
Is special insulation treatment required? ..................
Are damper windings required? ............................
Excitation...... volts de. Type of exciter ........... ......
Special characteristics (special efficiencies, etc.) ..............
MECHANICAL FEATURES
Protection or enclosure (drip-proof, splash-proof, etc.) ........
Number of bearings........ Type of bearings ..............
Coupling (half, whole, none) ........ Sole plates............
Engine type: Is shaft to be pressed into rotor? ...............
Is split stator required? ...... Split rotor? ...... Split hub? ....
LOAD DATA
Division of load (motors, lighting, etc.) .....................
Voltage regulation required ................................
Make and type of voltage regulator, is used .................
Will generator run in parallel with other generators?......... .
If so, give make and kind ................................
Motive power of other generators ........................
Are there any formal specifications? ........................
Additional information ....................................
While the foregoing material does not provide a
means for solving specific problems, it does indicate
the importance of providing complete information to
the builders of the power generating equipment. Where
consulting engineers draw up specifications, these will
usually give all of the required information. A brief
outline of the information required will be found in
Table 28.
TABLE 29B-APPROXIMATE KW RANGES AT-STANDARD SPEEDS AND VOLTAGES-DC GENERATORS
125 Volts 250 Volts 600 Volts
General-Purpose General-Purpose Standard
Speed in Generators Large Generators Large Large
Rpm and Exciters Generators and Exciters Generators Generators
High-Speed
1800-1750* 3/4 to 150
1200-1150* 3/4 to 150
900-850* 3/4 to 150
720-700 1 to 150
600-575* 1 to 150
514-500 1 to 150
- 3/4 to 150
200 to 250 3/4 to 150
200 to 300 3/4 to 150
200 to 500 1 to 150
200 to 600 1 to 150
200 to 1000 1 to 150
200 to 250
200 to 750
200 to 500
200 to 750
200 to 1250
200 to 1250
200 to 1250
200 to 1250
200 to 1250
200 to 2500
150 to 2000
200 to 2500
125 to 2000
200 to 2500
125 to 2500
200 to 3500
100 to 2500
200 to 4000
100 to 3000
200 to 4500
100 to 3000
200 to 4500
100 to 3500
200 to 5000
75 to 3500
200 to 5000
75 to 3500
200 to 5000
75 to 3500
200 to 5000
60 to 3500
200 to 5000
50 to 3500
200 to 5000
50 to 3500
200 to 5000
50 to 3500
200 to 5000
40 to 3500
200 to 5000
DIRECT-CURRENT GENERATORS
The standard kilowatt ratings of standard direct-
current generators and the approximate kw ranges
available at the various standard speeds are indicated
in Table 29. These speeds are approximately the same
as for 60-cycle synchronous generators so that the do
machines can be used with the same prime movers.
Speeds of generators direct-connected to internal-
combustion engines may range from 164 rpm for a
5000-kw unit to 1200 rpm or more for a 25 or 50-kw
unit. The lower speeds listed were originally set up for
the once popular Corliss-type steam engine. Vertical
multi-cylinder steam engines may have speeds up to
500 or 600 rpm in moderate capacities.
Since steam turbines perform most economically at
high speeds, they are usually geared to dc generators
with the maximum permissible speeds for the kw and
voltage ratings required.
TABLE 29A-STANDARD KILOWATT RATINGS
-DC GENERATORS
GENERAL-PURPOSE GENERATORS AND EXCITERS: 1,
1-1/2, 2, 3, 5, 7-1/2, 10, 15, 20, 25, 30, 40, 50, 60, 75, 100,
125, 150.
LARGE GENERATORS: 175*, 200, 250, 300, 350*, 400, 500,
600, 700*, 750, 800*, 900*, 1000, 1250, 1500, 1750, 2000,
2250*, 2500, 3000, 3500, 4000, 4500, 5000.
Low-Speed
450 2 to 125 150 to 1000 2 to 125
400 2 to 100 125 to 1000 2 to 100
360 2 to 100 125 to 1000 2 to 100
327 2 to 75 100 to 1000 2 to 75
300 2 to 75 100 to 1000 2 to 75
277 3 to 75 100 to 1000 3 to 75
257 3 to 75 100 to 1000 3 to 75
240 5 to 60 75 to 1000 5 to 60
225 5 to 60 75 to 1000 5 to 60
200 5 to 60 75 to 1000 5 to 60
180 71/2 to 50 60 to 1000 71/2 to 50
164 10 to 40 50 to 1000 10 to 40
150 10 to 40 50 to 1000 10 to 40
138 10 to 40 50 to 1000 10 to 40
128 10 to 30 40 to 1000 10 to 30
*AppliesAftlfC7VL&ibgiDbf-Rww&w,tsssi,;0, : CIA-RDP83-00423 R001200450002-7
 H-46 Approved For Release 1999/09/10 : CIA-RDP83-004231 1 10002-7
Fig. H-83. Diesel-driven 1700-kw, 327-rpm,
engine-type diect-current generator.
Standard voltages are 125, 250 and 600 volts for
2-wire units-125/250 volts for 3-wire units. Special
voltage generators area procurable, but the cost is
usually higher becauso of the added development
expense.
Standard open-type gneral-purpose generators are
rated 40 C rise for full-lead continuous dutir. However,
when operated at rated voltage and speed they will
carry continuously 1.15 times the rated load without
injurious temperature ~ rise, provided the ambient
temperature does not exceed 40 C.
Standard open-type low-speed generators and large
high-speed machines will carry 1.25 times their rated
load for two hours and hneet the following temperature
guarantees:
Core and windings..... .
Commutator....... .. .
Bare copper winding .. .
DC Generator Construction
Full-Load
Continuous
Duty
40 C
55 C
50 C
2&% Overload
for
Two Hours
55 C
65 C
65 C
High-speed generators in the general-purpose class,
that is, up through 150 kw, are usually furnished for
coupled service, with one or two end-shield type
bearings. Small sizes can be furnished for close-coupled
service. These generators have the same external
appearance as general purpose do motors (see pages
H-6, H-7, 11-38 and H 39) and are available with the
same types of protecti'e features.
For some speeds, Juch as 1200 rpm, end-shield
construction usually c,n be furnished for ratings up
to 300 kw at 250 or; 600 volts. Larger high-speed
generators generally are furnished with one or two
pedestal bearings for mounting on an extension of the
Figi H-84. End-shield bearing design is used for the
smaller dc generator ratings.
ow-speed generators (below 500 rpm) are usually
furnished in the engine type, that is, without shaft,
bearings or base. The armature is mounted on the
engine shaft, and the beari::rigs, and base if required,
are supplied by the engine builder. However, coupled-
ty e parts, including shaft, bearings, and sole plates
or ase, can be furnished if required.
Pa allel Operation
f two or more de generators are to be operated in
pa allel, it is essential that they have the same char-
ac ristics. That is, the terminal voltage drop from
no load to full load (with constant rheostat setting)
must be the same for all generators to be paralleled,
an the generator voltage regulation curves must
have similar shapes.
hunt-wound generators in. parallel form a stable
co dition under all ordinary circumstances. To obtain
exact division of the load, the percentage terminal
vo tage drop for a given percentage load change should
be the same for all machines. Ordinarily, division of
the load is controlled by adjustment of the respective
fie d rheostats.
en compound-wound generators are operated in
pa allel, equalizer connections must be used except in
ca es, such as street railway systems, where the genera-
tors are located quite a distance apart. In such cases,
the distances involved would make equalizer connec-
ti is ineffective, but at the same time the unavoidably
high resistances of the transmission lines make such
connections unnecessary; generator characteristics
in st, of course, be suited to this type of operation.
he purpose of the equalizer is to maintain the proper
current in the series windings of the machines so that
ea -,h armature will carry its proportionate share of
th load. Compound-wound generators can usually be
adjusted at the factory for parallel operation with
prime ~wed For Release 1999/09/10 : CI DPWtM4 3 112b 0O }7provided
 'Approved For Release 1999/09/10 : CIA-RDP83-00 fi Wtk 0450002-7 H-47
DC GENERATORS
the station wiring is such that the voltage drop from
the equalizer through the series field to the bus bars
at normal load is the same for all generators.
Paralleling of generators with and without interpoles
may be satisfactory under certain conditions but is
generally not recommended. Generators without inter-
poles have more rapidly drooping characteristics than
those with interpoles. At best, the interpole generators
will probably require external resistances in the series
circuits.
To parallel with standby storage battery systems,
generators should have a rapidly drooping voltage
characteristic from no load to full load. The generators
should be either shunt or differentially compound-
wound. If the batteries are to take the peak load, the
differential winding should be used so that the generator
voltage will drop faster with load than the battery
voltage.
From the foregoing it is obvious that the manu-
facturer must be supplied with complete information
if a generator is to be built to parallel with existing
generators. The information furnished should include
the nameplate data together with compounding and
regulation data and the voltage drop in the series
winding.
With this information, the machines can usually be
fully adjusted at the factory for parallel operation. If
the information is not available, or if the existing
generators have very unusual electrical characteristics,
it will be necessary to make final adjustments in the
field.
Three-Wire Distribution
In three-wire dc systems, the lower voltage between
the neutral and outside wires is used for lighting
TABLE 30-INFORMATION REQUIRED FOR SELECTING
DC GENERATORS
GENERAL
Type of generator (engine, coupled, belted) ..................
Quantity............ To be driven by ....................
Kw.... Rpm.... Voltage: Rated.... No load.... Full load.. .
Overload rating (if special) ................................
Ambient temperature ...... C Temperature rise .............
Class of Insulation: Armature... Field... Special treatment.. .
Two-wire or 3-wire...... Percent unbalance (if 3-wire) .......
service, and the higher voltage between the outside
wires is used for power. This provides an economical dc
distribution system. Its use is usually limited to 120/240
or 125/250 volts. There are two methods commonly
used to meet the demands for three-wire service.
One method uses the so-called three-wire generator,
with the voltage obtained by means of external auto-
transformers connected through collector rings to the
armature windings.
Basically, the construction of three-wire generators
differs from that of standard two-wire generators only
in the addition of two collector rings and suitable
brush rigging. The rings, which are usually mounted
on the shaft near the commutator, are connected to
suitable points of the armature winding. The lead from
each ring is connected to one leg of a balance coil,
which is usually separately mounted.
To make the compounding of the generator inde-
pendent of the unbalance of the load, the series fields
of three-wire generators are split into two circuits.
One circuit, consisting of the north poles, is connected
to one side of the armature, and the other, consisting
of the south poles, is connected to the other side of
the armature.
Standard construction provides for an unbalanced
load of 10 percent. Generators can, however, be built
for 25 or 50 percent unbalance.
The other three-wire system commonly used is the
rotary-balancer system, which consists of a two-wire
single-voltage generator operating with a rotary-
balancing set.
The rotary-balancer system has several advantages
that should be carefully considered. Regulation is
better than in other systems because the balancers
can be compounded to give full voltage at any desired
load. Any amount of unbalance can be handled, as
this depends solely on the size of the balancer. And
the full capacity of the generator is always available
whatever the condition of unbalance.
Table 30 gives an idea of the data required before
an intelligent selection of a do generator can be made.
MECHANICAL FEATURES
Protection or enclosure (drip-proof, splash-proof, etc.) ........
Number of bearings ........ Type of bearings ..............
Coupling (half, whole, none) ...... Sole plates ..............
Engine type: Is shaft to be pressed into armature?........... .
LOAD DATA
Nature of load ...........................................
Working voltage of plant..................................
Make and type of voltage regulator, if used ................
Will generator run in parallel with other generators? ..........
If so, give data .........................................
Are there any formal specifications? ........................ Fig. H-85. Geared 250-kw turbine-generator for
AdditionApp ed. For. Release 1999/09/10: CIA-RDF686004461 09"0"0 6rI-
 H-48 Approved For Release 1999/09/10 : CIA-RDP83-00423R00120045(Wo~--HT
M-G SETS II
Fig. H-86. Four Regulldx exciter sets, an 844-kw auxiliary synchronous m-g set, and :3500-kw flywheel m-g set
supporting 4000-hp, 0-50/120-rpm dc reversing blooming mill motor in.background.
MOTOR-GENERATOR SETS
Motor-generator sets,; consisting of a motor and one
or more generators, are used to transform electrical
energy from one form to another as follows:
1. From alternating 'current to direct current.
2. From direct current to alternating current.
3. From direct current to direct current at different
voltages.
4. From alternating current to alternating current
at different frequepcies.
Wherever practicable,; motor-generator sets are built
up of units of standard designs; but where this is not
feasible, special combinations are designed to suit the
requirements.
nder some conditions, the induction motor is
preferable to the synchronous motor for driving
ge erators of larger capacities. This is true, for example,
wh re the load on the generator is of a widely fluctuating
na ure. While the induction motor has the advantage
of not requiring excitation, its effect on the power
fac or of the system may be undesirable, especially
wh n the circuit supplies other apparatus taking a
lag ing current.
flywheel may be used to advantage with an induc-
tion set required to supply high peak loads of short
duration. Since the motor slows doom when the load
is applied, the stored energy in the flywheel then drives
the generator. This greatly reduces the temporary
excess load on the m-g set motor and on the main
ge crating system.
Alternating Current to Direct Current
Most electrical systems supply alternating current
because it can be more. economically transmitted and
distributed than direct current. Where direct current
is-desirable or essential, it can be obtained from an ac
system by means of an }n-g set consisting of an induc-
tion or synchronous niotor driving a do generator.
The choice of motor depends upon the conditions
to be met.
Induction Motor-Generator Sets
Alternating-current/direct-current motor-generator
sets rated less than 50i kw are almost invariably of
the induction motor-driven type, and most of these
have squirrel-cage induction motors. (Fig, 87.) They
are used to supply excitation, lighting, and general
power. Approved For Release 1999/09/10 :
ound-rotor motors are also used on flywheel m-g
set k. The control can be arranged to produce a greater
speed drop in the wound=rotor motor and 'thereby
fur her limit peak loads on the line supplying the
m- set motor.
Syr}chronous Motor-Generator Sets
he chief advantage of using synchronous motors to
dri e the dc generators of ra-g sets lies in the power-
fac or corrective effect that can be obtained by over-
ex Sting the field of the motor. In other words,
synchronous m-g sets can advantageously be used even
in fairly small ratings to correct poor power factor
res Elting from induction motors, transformers, are
lig ts, and other inductive apparatus on the circuit.
ynchronous motors do, however, require direct
DR e8Q423800fI2G046WO2'- -g sets,
 Approved For Release 1999/09/10: CIA-RDP83-0042311&T50002-7H49
M-G SETS
this is not a particularly significant disadvantage
though, since the set can readily be supplied with a
direct-connected exciter. In fact, the m-g set generator
can, if its voltage is not much above 250 volts, supply
the required excitation. Fig. 88 shows a large syn-
chronous motor driven motor-generator set.
Direct Current to Alternating Current
Although m-g sets for conversion of direct current
to alternating current are not in great demand, they
can readily be supplied if required. Such a combination
includes a do driving motor coupled to an ac generator.
Direct Current to Direct Current
Motor-generator sets consisting of dc motors driving
de generators are used to furnish a circuit with a
voltage different from that of the main power circuit
or with a voltage that can be varied independently.
Where a set supplies a special voltage circuit, the set
also serves to insulate the main and special circuits
from each other if their requirements differ.
Boosters sets are used when the load on some feeders
in a do distribution system requires a voltage regula-
tion for which the main generator cannot be adjusted
without disturbing the potential at other parts of the
system. The booster, connected in series with one wire
of the feeder, keeps the voltage constant or varying
to suit local conditions.
This method frequently has been used by central
stations to compensate for line loss in long runs. It is also
used to raise the voltage for battery charging. Booster
generators are usually driven at constant speed by
shunt-wound motors receiving power from the line.
A three-unit balancer is sometimes employed in
connection with a standard single-voltage do generator
to produce a multi-voltage supply from which dc
motors may be operated at various speeds.
For example, a three unit balancer generating 40,
80 and 120 volts used in connection with a 240-volt
generator would supply six voltages to the motors so
that they could be run at six different speeds. In
addition, field and armature control can be used to
TABLE 31
NEMA KILOWATT AND SYNCHRONOUS SPEED RAT-
INGS FOR 60 CYCLE 2 AND 3-PIIASE SQUIRREL-CAGE
INDUCTION MOTOR-DRIVEN SETS
Generators: 125 or 250 V Shunt or Compound-Wound
Motors: 110, 220, 440, 550 and 2300 V
Generator Motor
Motor Voltage
Rating
Rating
110
208-220-440-550 2300, Three-Phase
Kw Hp
Synchronous Speed-Rpm
1
2
1800
1800
11/2
3
1800
1800
2
3
1800
1800
3
5
1800
1800
5
71/2
....
1800
71/2
15
....
1800
10
15
....
1800
15
25
....
1800
20
30
....
1800
....
....
....
25
40
....
1800
....
....
1200
30
50
....
1800
....
1800
1200
40
60
....
1800
1200
1800
1200
50
75
....
1800
1200
1800
1200
60
100
....
1800
1200
1800
1200
75
125
....
1800
1200
1800
1200
100
150
....
1800
1200
1800
1200
125
200
....
1800
1200
1800
1200
150
250
....
1800
1200
1800*
1200
*250-volt generators only.
TABLE 32
NEMA KILOWATT AND SYNCHRONOUS SPEED
RATINGS FOR 60 CYCLE SINGLE-PHASE
MOTOR-DRIVEN SETS
Generators: 125 or 250 V Shunt or Compound-Wound
Motors: 110 or 220 V
Generator
Rating
Kw
Motor
Rating
IIp
Synchronous
Speed
Rpm
1
2
1800
11/2
3
1800
2
3
1800
3
5
1800
*5
*230-volt motor only.
71/2
1800
Fig. H-87. Two 15-kw induction m-g sets used for Fig. H-88. Synchronous m-g set rated 500 kw, 900
excit~q'gppb T-BlpFRpIW*-"o?99' IOW10 : CIA-RDFbegJ90 Fk06q,20V451d6-02ryrive.
 H-50 Approved For Release 1999/09/10 : CIAO-RDP83-00423 R0012004OC7HT
M-G SETS
increase or decrease the speed of the motors from the
six fundamental speeds, thus providing a wide range
of easy control.
As has already been noted in the discission of do
generators, a two--unit balancer can be used to change
a single-voltage, two-wire do system into a three-wire
system.
Alternating Current to Alternating Current
Frequency-changer sq,ts normally consist of a syn-
chronous motor driving a synchronous generator, but
occasionally an induction motor is used to drive the
synchronous generator.;
Since there is a fixed) relationship between speed and
frequency, the numbe~~ of poles for the motor and
generator must be, chosen so that the two frequencies
desired will be obtained! at the same speed. For example,
in changing from 60 toy 25 cycles a 300-rpm set can he
used; in this case the motor would have :34 poles and
the generator 10 poles.
Frequency changers are used (a) to interchange
power between two systems of different frequencies,
or (b) to supply power at either a higher or lower
frequency than that of. the available supply.
Another means of changing frequencies is the
induction frequency congerter set, consisting of a wound-
rotor induction machine driven by a suitable motor.
The primary circuits of the wound-roi,or machine
are connected to a fixed-frequency sours; of electric
power. The secondary circuits deliver ,power at a
frequency proportional, to the relative speeds of the
primary magnetic field and the secondary (rotating)
member. If a frequency higher than that of the power
lines is desired, the rotor of the frequency converter is
driven in the direction opposite to that in which it
would run as a motor.
By using a multi-speed or varying-speed driving
motor, the converter caii deliver a secondary frequency
that varies to suit the requirements. It should be
noted that the secondary voltage of the wound-rotor
machine varies directly as the secondary frequency.
Tables 31, 32, 33 and 34 give the standard NEMA
ratings for motor-generator sets.
TABLE 33
NEMA KILOWATT AND SYNCHRONOUS SPEED
RATINGS FOR 60 CYCLE 2 AND 3-PHASE SYN-
CIIRONOUS MOTOR-DRIVEN SETS, O.>, POWER
FACTOR LEADING AT FULL LOAD
Generators: 125 or 250'V Shunt or Compound-Wound
Motors: 220, 440, 550 or 2300 V
Generator
Rating
Kw
Motor
Rating
Hp
Synchronous
Speed
Rpm
50
75
1200
60
100
1200
75
125
1200
100
150
1200
Approved FoVRelease 1999/09/10: Cl
TABLE 34
MA STANDARD KILOWATT AND SPEED RATINGS
R SYNCHRONOUS MOTOR-GENERATOR SETS 200
KW AND LARGER
Rating
125 Volts--60 Cycles
Speed
Type
Kw
Rpm
of Set
200
1200
Two-Unit
250
1200
Two-Unit
300
1200
Three-Unit
300
900
Two-Unit
400
1200
Three-Unit
400
720
Two-Unit
500
1200
Three-Unit
500
720
Two-Unit
600
900
Three-Unit
800
720
Three-Unit
1000
720
Three-Unit
200
250 Volts--60 Cycles
1200
Two-Unit
250
1200
Two-Unit
300
1200
Two-Unit
400
1200
Two-Unit
500
1200
Two-Unit
600
900
Two-Unit
750
900
Two-Unit
1000
720
Two-Unit
1250
720
Two-Unit
1500
514
Two-Unit
2000
360
Two-Unit
2000
720
Three-Unit
2500
720
Three-Unit
3000
514
Three-Unit
4000
360
Three-Unit
300
600 Volts--60 Cycles
1200
Two-Unit
500
1200
Two-Unit
600
1900
Two-Unit
750
.900
Two-Unit
1000
720
Two-Unit
1250
720
Two-Unit
1500
514
Two-Unit
1750
514
Two-Unit
2000
514
Two-Unit
2000
720
Three-Unit
2500
:514
Three-Unit
2500
720
Three-Unit
3000
360
Three-Unit
3000
514
Three-Unit
3500
.514
Three-Unit
4000
.514
Three-Unit
5000
514
Three-Unit
6000
360
Three-Unit
tandard rating for two-unit motor-generator sets above
tandard rating for three-unit motor-generator sets above 4000
514 rpm, will be in steps of 1000 kw.
. H-89. Two 2500-kva, 600-rpm, 40/60-cycle
quency-changer sets. Generator in background has
-Rf P@&A1Y4i1& AN?' 45Q0$eTce.
 CPYRGHT
ALLIS-CHALMERS PRODUCTS
POWER GENERATION
STEAM TURBINES ... for all power plant applica-
tions ... ship propulsion.
GAS TURBINES ... for use with axial blowers in
process work ... power generation ... locomotives.
HYDRAULIC TURBINES ... Francis, propeller and
impulse types ... all sizes.
GENERATORS . synchronous, induction, direct
current ... vertical and horizontal ... all sizes.
GENERATOR VOLTAGE REGULATORS ...for
providing constant output voltage on generators of all
sizes.
SYNCHRO-OPERATORS . . . for full automatic
synchronizing of ac generators.
CONDENSERS . surface and jet types complete
with condensate and circulating pumps and drives
.. air ejectors.
BOILER FEED PUMPS ... drives.
WATER CONDITIONING equipment, chemicals
and service.
POWER TRANSMISSION AND
DISTRIBUTION
POWER TRANSFORMERS ... all sizes, including
load-ratio control, regulating, phase-shifting, rectifier,
furnace, and welding types.
DISTRIBUTION TRANSFORMERS ... urban and
rural types, net-work, subway, vault, non-inflammable,
and dry types.
INSTRUMENT, METERING TRANSFORMERS ...
complete line.
FEEDER VOLTAGE REGULATORS ... for station,
distribution and branch service.
SWITCHBOARDS to suit application.
SWITCHGEAR ... vertical lift metal-clad.
CIRCUIT BREAKERS . oil, magnetic and air
blast types ... outdoor and indoor ... manual and
automatic.
MOTOR CONTROL standard and special for
motors of all sizes above 1/2 hp.
UNIT SUBSTATIONS . . . single circuit, multi-
circuit and load center types.
POWER CONVERSION
RECTIFIERS . mercury arc power, with metal
tanks, single and multiple anode ... also permanently
evacuated type.
MOTOR-GENERATOR SETS . all sizes, with
synchronous or induction motor drive ... frequency
changers . . . converters.
SYNCHRONOUS CONDENSERS .. . for power
factor correction and improvement of system stability.
GENERAL INDUSTRIAL PRODUCTS
ELECTRIC MOTORS ... all types, synchronous, in-
duction, direct current, 1 hp up to largest ... motor
control.
TEXROPE DRIVES, multiple v-belt ... cast iron and
pressed steel sheaves . . . variable speed . . . speed
changers.
CENTRIFUGAL PUMPS ... single and multi-stage
... 10 to 300,000 gpm.
COMPRESSORS ... rotary sliding-vane.
BLOWERS ... single and multi-stage centrifugal ...
axial.
DIELECTRIC HEATERS ... for heating, dehydrating,
bonding, non-conducting materials.
INDUCTION HEATERS . . . for heating, brazing,
melting, metals.
METAL DETECTORS ... electronic device that safe-
guards quality ... prevents damage to machinery.
OTHER ALLIS-CHALMERS PRODUCTS
ROCK AND ORE CRUSHERS, VIBRATING SCREENS, GRINDING MILLS, WASHING EQUIP-
MENT ... KILNS, COOLERS, DRYERS ... COPPER AND NICKEL CONVERTERS ... FOUNDRY
SHAKEOUTS AND ELECTRONIC CORE DRYERS ... HYDRAULIC LOG BARKERS ... GRAIN
AND CHEMICAL MILLING MACHINERY ... SOLVENT EXTRACTION PLANTS ... BETA-
TRONS ... WHEEL AND TRACK-TYPE TRACTORS . . . TRACTOR DRAWN FARM IMPLE-
MENTS ... ROAD AND CONSTRUCTION EQUIPMENT ... GASOLINE POWER UNITS.
Approved For Release 1999/09/10 : CIA-RDP83-00423R001200450002-7
 An Prl Fnr Please 1999109110, : CiA-
ALLIS-CHALMERS S
General Offires...Allis-Chalmers Manufacturing
Telephone
NE
P83-00423P001.200450002-T,
CPYRGHT
LES OFFICES
Company, Milwaukee 'l, Wisconsin
Telephone
MEXICO
Birmingham 3, 2000 First Ave., North... ...... 4-5494 Alb
ARIZONA i
Phoenix, 30 West M#dison St......... ..ALpine 3-2159
CALIFORNIA
Los Angeles 13, 4171S. Hill Sr......... Mt.dison 6-2231
San Diego 1, 747 ],'Ninth Ave. ......... Main 8-4684
San Francisco 7, 650 Harrison St....... Douglas 2-8384
COLORADO
Denver 2, 1920 Market St- .............Cherry 6556
CONNECTICUT
Hartford, 750 Main Sr ............... Hartford 46-5675
New Haven 10, 157 Church St. ......... ... State 7-1176
DISTRICT OF COLUMBIA
Washington 5, 14th & H Sts., N. W.... Ex:cutive 3-2800
FLORIDA
Jacksonville 7, 2031 .Hendricks Ave ............. 98-1651
Miami 32, 25 S. E. 2nd Ave............. Miami 2-7744
Tampa 2, 405 S. Mprgan St.... ...............2-8371
GEORGIA
Atlanta 3, 57 Forsythe St., N. W........... Walnut 7116
ILLINOIS
Chicago 3, 135 Soy LaSalle St......... Franklin 2-6480
Peoria 2, 301 S. Adams St.. ........... ...... 4-9279
Rockford, 303 North Main St .......... ...... 5-5721
INDIANA
Evansville 9, 129 Locust St.. ................ 4-8219
Indianapolis 4, 11 S. Meridian St.......... MArket 7415
IOWA
Davenport, 326 W.I Third St ................... 3-9793
KANSAS
Wichita 2, 111 So Main St.. ................... 3-97
KENTUCKY
Louisville 2, 241 S4 i Fifth St ............ .... Clay 7656
LOUISIANA
New Orleans 12, 210 Baronne St......... Raymond 8623
Shreveport 23, 624 Travis St. .... ............ 2-3274
MAINE
Augusta, 269% later St ................. Augusta 463
MARYLAND
Baltimore IS, 11 L5 East 30th St....... HOpkins 7-4480
MASSACHUSE'T'TS
Boston 16, 31 Sr. James Ave........... Hubbard 2-3700
MICHIGAN I
Detroit 2, W. Grand Blvd. & 2nd Blvd. Trinity 1-2300
Grand Rapids 2, 5-7 Lyons St., N. W........... 9-8249
Jackson, 297 W. !Michigan Ave ....... ......... 2-2419
MINNESOTA 1
Duluth 2, 10 E. Superior St. ..................7-5061
Minneapolis 2, 8~1 Marquette Ave....... ATlantic 6455
MISSOURI
Kansas City 6, 6 East 11th St ............. Victor 0132
St. Louis 3, 1205 Olive Sr ...............Central 4313
NEBRASKA
Omaha 2, 14th& Farnam Sts......... Atlantic 1780
NEW JERSEY
Newark 2, 1060 road St. ............. Market 3-7170
YORK
lo 3, 535 Washington St......... Washington 1741
York 7, 50 Church St .............. Beekman 3-9100
ester 4, 241 East Ave., ....Ave.................. Baker 7510
use 2, 472 S. Salena St......... Syracuse 3-0147
Ch lotte 2, 212 S. Tryon St ......... .......... 2-3188
0 '1 0
Ak n 8, First National Tower............ Portage 7648
Cin innati 2, 617 Vine St ............... Main 7300
Cle eland 14, 815 Superior Ave., N. E..... Main 1-5182
Tol do 4, 245 Summit St ................. Adams 5269
Yo ngstown 3, 25 E. Boardman St..... Riverside 3-5175
O LAHOMA
Ok ahoma City 1, 401 N. Harvey St...... Regent 9-1631
Tu sa 3, 320 E. Archer St ...................4-9163
O EGON
Po tland 4, 520 S. W. 6th Av........... Capitol 9835
P SYLVANIA
Ph ladeiphia 3, 1617 Pa. Blvd....... Rittenhouse 6-8412
Pi sburgh 19, 421 Seventh Ave........ Atlantic 1-4154
W lkes-Barre, Market & Franklin Sts., (Bell) W.B. 3-2413
Y rk, 42 East King St ................... York 5415
R ODE ISLAND
Pr vidence 3, 111 Westminster Sr....... Jackson 1-8820
T NNESSEE
C attanooga 2, 737 Market St....... .......... 6-5101
K oxville 2, 531 S. Gay St ......... .......... 2-2165
=phis 3, 46 N. Third St .................. 5-0583
TEXarilloAS
A , 301 Polk St .......................31766
B aumont, 490 Bowie St .....................5-2535
El Paso, Corner Oregon & Mills Sts. - ........... 3-7439
Fbrt Worth 1, 408 West 7th Sr........... FAnin 5083
IRGINIA
ichmond 19, 627 East Main St ........ ....... 3-6646
ASHINGTON
EST VIRGINIA
ISCONSIN
lwaukee 2, 715 N. Van Buren St.,-BRoadway 1-4729
ontreal, Quebec, 1520 Mountain Sr......... Ma. 2411
Distributors in all principal cities throughout the United States
Offices and distributors locat d throughout the world
Approved For Release 1999/09/10 : C~A-RDP83-00423R001200450002-7
 Approved For Release 1999/09/10: CIA-RDP83-00423RO01 00'2-7
INDEX
Subject Page
Condensers, synchronous __-___ 33-35
Direct Current Motors ---_--_ ---___--__ 35-40
Control ------------- -_ 38-40
Enclosures --------------------------------------------------
Types ------------------------------------------------------------
Generators -------------------------- ----------------- 41-47
Alternating current ------------------------------------ 41-45
Construction ---.----------------------------------------- 42
Parallel operation ---------------------------------- 43
Regulation ------------ ------------------------ 43
Selection -------------------- -----------------------------
45
Direct current ------------------ ___-------- 45-47
Induction Motors -------------------------------------------- 14-25
Applications ------------------ -------- ---- 19
Characteristics ------------------------------------------ 15
Comparisons with synchronous ---------------- 32
Construction features -------___ _-------- 14
Design classification, NEMA _--------- ---------- 16
Double cage ------------- __-__ 19
Frame sizes ------------------------------------------------ 23
Multi-speed -------------------------------------------------- 21
Operation on off-standard circuits ------------ 25
Torques -------------------------------------- ------ 16, 21
Wound-rotor ----------------------------------------------- 21
Introduction ---------------------------------------------------- 1
Motors, general ---------------------------------------------- 1
Bearings ---- --------------------------------------- 13
Comparisons --- -------------------------------- 11
Cooling -------------------------------------------------------- 4
Subject Page
Direct current-see dc . ---------------------__------ 35-40
Induction, see induction 14-25
Insulation limits _-____ -------------- 4
Protection mechanical ------------------------------ 4-11, 22
Ratings ----------------- ---------------------------- 2
Selecting ---__ ___ 11,13
Speed characteristics --------------------------------- 2
Synchronous-see synchronous ____ 25-32
Temperature limits ------------------------------------ 4
Torque ----- ----------------------------------------
Motor-Generator sets _-_------------------------------ 48-50
AC to DC ------------------- ------- 48
DC to AC -------- ------------ 49
DC to DC -_-_-_- __-__
AC to AC --------------------------- --------- 50
Power Factor Correction ._. --------------------------- 26, 35
Standardization ---------------------------------------------- 1
Synchronous Condensers _ ------------------- 33-35
Synchronous Motors -------------------------------------- 25-32
Standard ------------------------------------------------------ 25-32
Construction of ------------------------ _____ 30
Excitation ---------- -------------------------- 31
Power factor of -------------------------------------- 26
Protection of ------------------------------------------- 31
Speeds, standard -- --------------------------------- 27,30
Starting --------- ----------------- 26
Torque requirements -------------- 26-29
Vertical ---------------------------------------------------- 30
Voltages, standard -------------------------------- 27
Approved For Release 1999/09/10 : CIA-RDP83-00423ROO1200450002-7
 V - I I ATIG" F-1-f ,I I
Here's a pump specially designed or quick, easy applica-
tion to hundreds of everyday pumping jobs. It offers you
top value for your pumping dollar because it has all the
quality features that you need to keep your pumping costs
low, yet its price is exceptionally low.
Quality Features. You get high grade construction,
such as ball bearings, mechanical shaft seal, and generous
metal sections. Built to the same top quality precision
standards as all Allis-Chalmers pumps.
Easy Installation. The Allis-Chalmers frame type pump
is built or e ve. IL Lan be IIIUU11L(:Zt
i
positions and connected to any type of prime mover with-
out difficult alignment problems.
Wide a
pumping jobs requiring capacities up to 500 gpm and
heads as high as 135 feet. Head and capacity can be
changed by simply changing sheave size on the V-belt
drive. One pump can serve you many places with only
this simple change.
Low Maintenance. Rigid base holds alignment, keeps
bearing wear down. Mechanical seal requires no attention
in normal service. Wearing rings on larger pumps mean
efficiency can be maintained easily through years of service.
if yen iinve ~e@" io8kitqg, fog; 10
petitive price, you'll find it among these Allis-Chalmers
frame type pumps. _
 CPYRGHT
d f
scast iron frame pre-
viE ibratian, maintains)
ment , Mounting bolt,
0aroeasily accessible,
I' a Single' row ball bear -
iggswell supported in a
rigid cast On frame carry
tte shaft.. Bearings are
grease lubricated through a
s ngle point in the frame.
Two single row ball bear.
Ings well supported in a
rigid cast iron frame carr
the shaft, Bearings are
grease lubricated through a
single point in the frame.
CAP -RDP83-0
A sG er and seal assembly
'keep liquid out of bear-
ings, prevents rust and
corro ion. \
,
good for hundred; of hours
of operation without atten-
tion.
Mechanical seal makes
packing unnecessary, is
good for hundreds of hours
of operation without atten.
tion. \
A linger and seal assembly
k ps liquid out of bear-
in s, prevents rust and
co rosion.
Rigid cast iron frame pre
vents vibration, maintain:
alignment. Mounting bol
holes are easily accessible
Te ra r'wbal ar-
~i ported rn a
ii c irp frarpe carry
A - 4. ,. a rugs are
gr a dbrica ed through a
sore paint i the frame.
MBChanical seal makes
packing unnecessary, is
good for hundreds of hours
of operation without atten-
L
tion.
A slip er and seal assembly
steep liquid out of bear-
ings, prevents rust and
carro bit:
I an--
a d cast iro erne pre, ains,
kg tk ble
'se recip n Cast bronze im?
sac ng unnecessary
is r ller is of enclosed type
Cast and machined bronz
impeller is of open type.'
I
IN
Smooth surfaces inside and
out speed water flaw, keep
efficiency high.
Cast bronze impeller is of
enclosed type. Smooth sur-
faces inside and out speed
water flow, keep efficiency
high. Wearing rings front
and rear on larger sizes,
front only on smaller sizes.
 CPYRGHT
Approved For Release 1999/09/10 CIA-RDP83-00423 8401200450002-7
-~ r 7
Size....
I x 3/4
11/4 x 1
A
13'/2
141/,6
B
11/a
1216
C
21a
1/a
D':
2/s
33/6
E
2a/a
2
F
33
215/16
Size..
11/2 x1'/2
2x2
2'/2 x2'/2
3x3
A
145/s
14%
14/a
15
C
21/2
2/a
2%
2/a
D
45/8
43/4
4 /a
5
E
2%
31/4
3/a
4'/2
F
31/8
3'/4
3 j6
3%
G
11%
11
11/4
11%2
Size....
1 x 1
21/2 x 21
A
10,
141/a
B
7 A
113/a
C
2%s
2'/a
D
11/a
2/a
F
25A6
41/a
G
7/4
10
H
6/8
31/z
J
4%
6
K
1/2
11/4
L
1'/z
11/4--
M M
21/2
3 _
N
'/a
0
1'/2
2
 VAR.- cumEA-6512
s*E1 X
ImP
P-10
TYPE SS-RHB
'!5 MAx Du
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.
MAX. sPNER6 y
.
'32 3
L-
R
~.
)19
. I
P
L
E
S
I
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7
8
10
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1
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E
.
lij%j" ISO
"EI.~XIJ. 00FSS-BHB'~'
.,,
"P .P-1071 M . IA.3}fr..
VAR R M-CVRVF A -640T slzE I X I 'T 'Po 5S C R 5
IMV: P 1017 A IA 4 '
MAx ERF~. Mw. DIa ~,
_rV
-
VAR. RPM CURVE A-6511
sizol.14X I OrooSS-RrlE
MP. P-1070 MA%
UTA 6'
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MAD. SPHF!iE ` N. DIA. 3
-
JEI
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b
a.
---
30-40,
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