
Operating Characteristics of Induction Motors 183
TORQUE-SPEED CURVES - INFLUENCE OF
ROTOR PARAMETERS
We saw earlier that the rotor resistance and reactance in-
fluenced the shape of the torque-speed curve. Both of these
parameters can be varied by the designer, and we will
explore the pros and cons of the various alternatives. To
limit the mathematics the discussion will be mainly quali-
tative, but it is worth mentioning that the whole matter
can be dealt with rigorously using the equivalent circuit
approach.
We will deal with the cage rotor first because it is the
most important, but the wound rotor allows a wider vari-
ation of resistance