Question

If use auto transformer method starting to start an induction motor to replace star-delta method, then the required tapping on the transformer will be _________

(a) 57.73%

(b) 86.7%

(c) 57%

(d) 66.66%

I had been asked this question at a job interview.

I'm obligated to ask this question of Principle of Operation topic in chapter Induction Machines of Electrical Machines

Answer 1

The correct answer is (a) 57.73%

To elaborate: k = 1/1.73 = 57.73%.