Engineering Board Exam Reviewer · Three-Phase Systems in Power Applications · hard
A three-phase, four-wire wye system with a 120 V phase voltage (VAN=120 0°, VBN=120 -120°, VCN=120 120°) feeds the unbalanced resistive loads shown: RA=8, , RB=10, , and RC=24, . Find the neutral current in polar form.
- 8.89 43° A
- 32 0° A
- 8.89 137° A
- 8.89 -43° A
Answer
D. 8.89 -43° A
Solution
The line currents are IA=120 0°/8, =15 0° A, IB=120 -120°/10, =12 -120° A, and IC=120 120°/24, =5 120° A. The neutral wire carries their phasor sum: IN=IA+IB+IC=8.89 -43° A.
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