Question

Speed of a permanent magnet DC motor:

(a) It is directly proportional to the armature voltage at a given load torque

(b) The speed torque characteristics are more flat than in a wound field motor

(c) It depends upon armature voltage and are more flat than in a wound field motor

(d) None of the mentioned

The question was asked in a job interview.

Question is from Controller Components in division Control System and Components of Control Systems

Answer 1

The correct answer is (c) It depends upon armature voltage and are more flat than in a wound field motor

The explanation: Speed of a permanent magnet DC motor is directly proportional to the armature voltage at a given load torque and speed torque characteristics are more flat than in a wound field motor as the effect of armature reaction is less pronounced in a PM motor.