Question

The CT supplies current to the current coil of a wattmeter power factor meter, energy meter and, an ammeter. These are connected as?

(a) All coils in parallel

(b) All coils in series

(c) Series-parallel connection with two in each arm

(d) Series-parallel connection with one in each arm

I have been asked this question during an interview.

This is a very interesting question from Advanced Problems on C.T. and P.T. topic in section Extension of Instrument Ranges of Electrical Measurements

Answer 1

Correct option is (b) All coils in series

For explanation I would say: Since the CT supplies the current to the current coil of a wattmeter, therefore the coils are connected in series so that the current remains the same. If they were connected in parallel then the voltages would have been the same but the currents would not be the same and thus efficiency would decrease.