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 IR. Assume the phase sequence to be RYB.

(a) 44.74∠-63.4⁰A

(b) 44.74∠63.4⁰A

(c) 45.74∠-63.4⁰A

(d) 45.74∠63.4⁰A

The question was posed to me in exam.

I want to ask this question from Three-Phase Balanced Circuits in chapter Polyphase Circuits of Network Theory

Answer 1

The correct option is (a) 44.74∠-63.4⁰A

The explanation is: 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 IR = (400∠0^o)/(8.94∠63.4^o )= 44.74∠-63.4⁰A.