Question

What are the disadvantages of the low rated secondary current transformer?

(a) high cost

(b) high voltages

(c) high voltages or high cost

(d) high voltages and high cost

I had been asked this question in an interview.

The origin of the question is Design Principles topic in portion Design of Current Transformers (CT) of Design of Electrical Machines

Answer 1

Correct answer is (d) high voltages and high cost

For explanation I would say: When there is a low secondary current rating in the current transformers they produces high voltages if the secondary is left open. It is also costly to produce the windings because of the extra time involved in the making.