Question

Errors in a C.T. can be minimised by _________

(a) making use of laminations

(b) having low reactance

(c) increasing the secondary winding turns

(d) decreasing the primary winding turns

I have been asked this question in an interview.

The question is from Errors in Current Transformers in section Extension of Instrument Ranges of Electrical Measurements

Answer 1

Correct choice is (b) having low reactance

The explanation: The excitation current Io can be minimised thus eliminating the errors in a C.T. by minimising the iron loss. The core must have a low iron loss and a minimum value of leakage reactance.