Question

What is the formula for the copper loss in the synchronous machine?

(a) copper loss per phase = current per phase * dc resistance

(b) copper loss per phase = current per phase2 * dc resistance^2

(c) copper loss per phase = current per phase2 * dc resistance

(d) copper loss per phase = current per phase * dc resistance^2

The question was posed to me in an interview for job.

This interesting question is from Losses and Temperature Rise in chapter Design of Synchronous Machines of Design of Electrical Machines

Answer 1

Right choice is (c) copper loss per phase = current per phase2 * dc resistance

For explanation I would say: First the current per phase is calculated and the value is squared. Next the dc resistance is calculated and the sum of the square of the current per phase and dc resistance gives the copper loss per phase.