Question

How many classes have their temperatures above 100°C?

(a) 5

(b) 6

(c) 7

(d) 8

I have been asked this question in semester exam.

This intriguing question comes from Temperature Rise and Insulating Materials in portion Electrical Engineering Materials of Design of Electrical Machines

Answer 1

The correct answer is (b) 6

The explanation is: There are 7 insulation classes present in relation with temperature. Of the 7 classes, there are 6 classes whose temperatures are greater than 100°C. Class Y is the only class having temperature less than 100.