Question

A three-phase balanced delta connected load of (4+j8) Ω is connected across a 400V, 3 – Ø balanced supply. Determine the phase current IY.

(a) 44.74∠183.4⁰A

(b) 45.74∠183.4⁰A

(c) 44.74∠183.4⁰A

(d) 45.74∠-183.4⁰A

This question was addressed to me during an online exam.

I'd like to ask this question from Three-Phase Balanced Circuits topic in section Polyphase Circuits of Network Theory

Answer 1

The correct choice is (c) 44.74∠183.4⁰A

Easy explanation: Taking the line voltage VRY = V∠0⁰ as a reference VRY = 400∠0⁰V, VYB = 400∠-120⁰V and VBR = 400∠-240⁰V. Impedance per phase = (4+j8)Ω = 8.94∠63.4⁰Ω. Phase current IY = (400∠120^o)/(8.94∠63.4^o)= 44.74∠-183.4⁰A.