Question

What is the value of the alternative core lengths below which variation in rating can be obtained?

(a) 0.7 * length

(b) 0.4 * length

(c) 0.3 * length

(d) 0.7 * length or 0.5 * length

I had been asked this question during an interview for a job.

My question is taken from Separation of D and L, Standard Frames topic in section General Concepts and Constraints in Design of Rotating Machines of Design of Electrical Machines

Answer 1

Correct answer is (d) 0.7 * length or 0.5 * length

Best explanation: The variation in the ratings can be obtained using alternative core lengths. The value of the alternative core lengths below 0.5 * length or 0.7 * length provides the variation in the ratings.