Question

What is the best number of secondary turns of the current transformer?

(a) 1

(b) 2

(c) 1 or 2 less than the number such that the turns ratio is equal to the nominal current ratio

(d) 1 or 2 more than the number such that the turns ratio is equal to the nominal current ratio

I had been asked this question in exam.

My enquiry is from Turns Compensation in portion Design of Current Transformers (CT) of Design of Electrical Machines

Answer 1

Right answer is (c) 1 or 2 less than the number such that the turns ratio is equal to the nominal current ratio

Explanation: The best number of secondary turns of the current transformer is 1 or 2 less than the number such that the turns ratio is equal to the nominal current ratio. For example in a 1000/5 current transformer, the secondary turns number would be 198 or 199 rather than 200.