ABSTRACT
In the integral horsepower sizes, i.e., above 1 hp, three-phase induction motors of various types drive more industrial equipment than any other means. The most common three-phase (polyphase) induction motors fall within the following major types:
NEMA (National Electrical Manufacturers Association) design B: Normal torques, normal slip, normal locked
amperes
NEMA design A: High torques, low slip, high locked
amperes
NEMA design C: High torques, normal slip, normal
locked amperes
NEMA design D: High locked-rotor torque, high slip
Wound-rotor: Characteristics depend on external resist-
ance
Multispeed: Characteristics depend on design-variable
torque, constant torque, constant horsepower
There are many specially designed electric motors with unique characteristics to meet specific needs. However, the majority of needs can be met with the preceding motors.
