
Operating Characteristics of Induction Motors 201
Torque
Speed
Figure 6.16 Influence of external rotor resistance on torque-speed curve of
wound-rotor motor
POWER-FACTOR CONTROL AND ENERGY
OPTIMIZATION
In addition to their use for soft-start and speed control,
thyristor voltage regulators are often marketed as power-
factor controllers and/or energy optimizers for cage motors.
Some of the hype surrounding their introduction has
thankfully evaporated, but users should remain sceptical of
some of the more extravagent claims which can still be
found.
The fact is that there are comparatively few situations
where these considerations alone are sufficien ...