Question

How is the transient short circuit current related with the air gap density?

(a) air gap density is directly proportional to the short circuit current

(b) air gap density is indirectly proportional to the short circuit current

(c) air gap density is directly proportional to the square of the short circuit current

(d) air gap density is directly proportional to the square of the short circuit current

I have been asked this question in an online interview.

My question is based upon Synchronous Machines Output Equation topic in section Design of Synchronous Machines of Design of Electrical Machines

Answer 1

The correct choice is (a) air gap density is directly proportional to the short circuit current

To explain: The air gap density is directly proportional to the short circuit current. The air gap density should be kept low in order to reduce the initial electromagnetic forces under short circuit condition.