Product Manual

-18-
The following table can be used to help guide which design type should be selected:
NEMA Electrical Design Standards
Polyphase
Characteristics
Design A
High locked rotor
torque and high
locked rotor current
Design B
Normal locked rotor
torque and normal
locked rotor current
Design C
High locked rotor
torque and normal
locked rotor current
Design D
High locked rotor
torque and high slip
Design E
Normal locked rotor
torque and current,
low slip
Locked
Rotor
Torque
(% Rated
Load
Torque)
70-275 70-275
200-285
275
75-190
Pull-Up
Torque
(% Rated
Load
Torque)
65-190 65-190
140-195
NA
60-140
Break-down
Torque
(% Rated
Load
Torque)
175-300 175-300 190-225
275
160-200
Locked
Rotor
Current
(% Rated
Load
Current)
Not
defined
600-700 600-700 600-700
800-1000
Slip
0.5-5% 0.5-5%
1-5% 5-8%
0.5-3%
Relative
Efficiency
Medium or
high
Medium or
high
Medium
Low
High
Typical Applications
Fans, blowers, centrifugal pumps
and compressors, motor-generator
sets, etc., where starting torque
requirements are relatively low
Fans, blowers, centrifugal pumps
and compressors, motor-generator
sets, etc., where starting torque
requirements are relatively low
Conveyors, crushers, stirring
motors, agitators, reciprocating
pump and compressors, etc.,
where starting under load is
required
High peak loads with or without
flywheels such as punch presses,
shears, elevators, extractors,
winches, hoists, oil-well pumping
and wire-drawing motors
Fans, blowers, centrifugal pumps
and compressors, motor-generator
sets, etc., where starting torque
requirements are relatively low