Question

What percentage of the rated output for DC machine and synchronous machine is taken as stray load losses respectively?

(a) 1% and 0.5%

(b) 0.5% and 1%

(c) 3% and 0.1%

(d) 0.1% and 5%

The question was asked during an interview for a job.

The origin of the question is Losses and Efficiency topic in chapter Rating and Loss Dissipation of Electrical Machines

Answer 1

Right choice is (a) 1% and 0.5%

To elaborate: Stray load losses cannot be determined accurately. In DC machine, by convention, it is taken as 1% of the rated output for rating above 150 KW. For synchronous and induction machine, it is taken as 0.5% of their rated output.