Question

1. A balanced delta-connected load has 12 +j16 ohms impedance per phase, and is energized by 208 V line-to-line. The phase sequence is ‘a-b-c'. (a) Find the line and phase voltages and currents at the delta load, and show them in a phasor diagram. (b) If the delta-connected load is rewired and connected in wye, show the line and phase voltages and currents at the wye load in a phasor diagram.

Answer 1

Taking the line voltoge Vab = VLo° as Teference Va6= 208 Lo° Derfa- Comected load Voc= 208 -120 V Vca= 208 28 v (12 +ji 6le Impedance par phase 20 L53-1° Phale Curtonts 208 Lo° 10.4 L-531° A 20 LS3-1° 20e L-120 20 L53.1°2 3.1 = l0.4 L 208 L-240° 20 L S3:1° = lo.4 L-293.1A Curronts, The hree ime ime Current alie 3 times phake res pective the CUrrents 38 beknd the phase Currents · Bx 10.4 L-S3-1° - 30° 17.32 L-83.10 T2 = (7.32 31° -30° c19.32 L-203-1°A I3 = 17.32 L-23.1° - 30° = 17.32 L-323.1A Delt a- Cormected, þhole vottage & IN ene same. VL = VeR

Phosor - olibgrom Vca I3 ф 30° VBC Star, Comme cted nm lead es Me heured 20 531° = 6.66 25312 w/ mped Orce þer phase thon Lee have, voltoge taung Vab as the breference þhase voltoges 208 Loo Van = 120 L°v 120 L-126 N 120 L-24o Nen= (bbase. Current8 120 L8 la = Van 182-53.10 A al·ES 7 99.9 18 L-173.PA Zph (20 L-120° I8= Zph - 120 L-140° 6.66 L53.10 18--293-1°A phare. Cusrents Current ie, airo there * Stan Come Cted IL=I ph line Tefresents

PHA SOR DIAGRAN -VBN NCN Ic VAB VCA 128 VAN VBN VBC NOL tages by 30 lecals pha Se Line vol tages