Question

The excitation current of a C.T. _________

(a) varies over a fixed range of operation

(b) varies over a wide range of normal operation

(c) is fixed over a range of operation

(d) is fixed always

The question was posed to me at a job interview.

Query is from Differences between C.T. and P.T. in section Extension of Instrument Ranges of Electrical Measurements

Answer 1

Right option is (b) varies over a wide range of normal operation

The explanation is: In a potential transformer, the excitation current remains constant under normal operation. While in a current transformer, the excitation current varies over a wide range of operations.