
its field windings in series with the armature. A separately excited generator has field
windings, which are not connected electrically to the armature and which are energized
from a separate power source. The compound generator has both series and shunt
windings.
NEMA MG 1, Motors and Generators provides Design Letters for polyphase induction
squirrel-cage medium motors. Those Design Letters provide information regarding locked-
rotor torque, pull-up torque, and slip values at rated torque and are shown in Table 8.1.
Reference MG 1 for specific Design Letter information based on motor horsepower, speed,
and frequency. MG 1 also lists Design Letters