Question

Reducing the armature voltage will give us _______________

(a) Variable torque speed control

(b) Constant torque speed control

(c) Variable and constant both can be achieved

(d) Cannot comment on torque

This question was posed to me in an online interview.

This interesting question is from Ward Leonard Speed Control Method in division DC Motors of DC Machines

Answer 1

Correct option is (b) Constant torque speed control

For explanation: As seen from speed torque characteristics, reducing armature voltage will reduce the speed of the motor below base value but torque will remain same. Thus, reducing armature voltage will give constant torque speed control.