Question

If the load impedance is Z∠Ø, the expression obtained for current (IB) is?

(a) (V/Z)∠-240+Ø

(b) (V/Z)∠-240-Ø

(c) (V/Z)∠240-Ø

(d) (V/Z)∠240+Ø

I have been asked this question in an international level competition.

Enquiry is from Three-Phase Balanced Circuits in chapter Polyphase Circuits of Network Theory

Answer 1

Correct answer is (b) (V/Z)∠-240-Ø

Explanation: As the load impedance is Z∠Ø, the current flows in the three load impedances and the current flowing in the B impedance is IB = VBR∠240⁰/Z∠Ø = (V/Z)∠-240-Ø.