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

This question was addressed to me by my college professor while I was bunking the class.

This question is from Losses and Efficiency in portion Rating and Loss Dissipation of Electrical Machines

Answer 1

Right choice is (a) identical speed and excitation

To elaborate: For same iron and frictional losses, same frequency should be there. For that same speed must be run.