Question

If two series motors are identically coupled. One is running as motor while other as generator. For this combination, the iron losses and frictional losses are found identical for ____________

(a) identical speed and excitation

(b) identical speed

(c) identical rating and construction

(d) none of the mentioned

The question was posed to me by my school teacher while I was bunking the class.

Question is from Cooling (Loss Dissipation) in section Rating and Loss Dissipation of Electrical Machines

Answer 1

Correct answer is (a) identical speed and excitation

The explanation is: For same iron and frictional losses, same frequency should be there. For that same speed must be run.