Question

Which of the following are the classes of insulating material in electrical machines?

(a) Γ, A, E, F, H, C

(b) Γ, E, B, F, H, C

(c) A, E, B, F, H, C

(d) Γ, A, E, F, C

I have been asked this question by my school principal while I was bunking the class.

The question is from Motors in section Rating and Heating of Motors of Electric Drives

Answer 1

The correct answer is (a) Γ, A, E, F, H, C

To elaborate: Depending upon the temperature limits, insulating materials are classified into seven classes Γ, A, E, B, F, H, C. The insulation has the lowest temperature limit.