Question

If higher terminal voltage is applied to PMDC what will happen?

(a) Speed at 0 torque will be reduced

(b) Torque at 0 speed will be reduced

(c) Torque at 0 speed will be increased

(d) Torque will remain constant

This question was addressed to me in a national level competition.

I need to ask this question from PMDC Motors in division DC Machines of DC Machines

Answer 1

The correct choice is (c) Torque at 0 speed will be increased

Easy explanation: The straight-line characteristic of PMDC is such that it produces positive intercepts on both axes. If terminal voltage is increased both of these intercepts increases, slope remaining constant. Thus, speed and torque at initial conditions both will increase.