Question

UISIZULU Problem 4 A three phase, 5 kW, wye-connected load operate onnected load operates at 0.8 power factor lagging with a terminal voltage of 100 V (line to line). The cables connecting e bles connecting each phase of the load to the wye-connected supply has an impedance of (0.25 +0.25) 12. Compute the following: a) Reactive power drawn by the load. b) Real and reactive power losses in the system. me current and line voltage at the source terminals and the power factor at the source. Tune Wye source VO Wye load

Answer 1

The power system network is, having 2 whe a connected load 5kw at 0.8 lagging with voltage of loov (2-2) & caple per phare impedancelafis 0.25 +jo.rs re (a) Active power drawn by load (PL) = $3V, I, ws 8=5kw. I, 3x100 x 0.8 -= 36.0SA. Reactive power drawn by load (Q) = {3 \ I sind cos 0 = 0.8 7 6 = 36.86 & sinp = 0.6 Q = 23 x1000 36.08 8006 = 3749.54€ VAR Reactive power drawn by load is 3.749 KVAR (b) Real Pored loss in line = I IR S. IZ=Rtix] - (36.08) ² * 0.25 (Real Power loss = 325.44 watt! Reactive power loss in line= I2*x = 36.08)² x 0.25 I leartive power loss & 325.44 VAR

(c) Total power drown by the sondece is Total Real Powerpt Real Prueet loss by line + Real Power drawn by load p= 325.44 + 5000=5325.44 Watt Total Reactive Powera) = 325.44 +3749.54 Q = 4074.9816 VAR Total complex power (8) = V peta² = (15 325.443 +4074983 s = 6705.65VA complen power is' is written as SzBV, I = 6705.65 source line current is equal to load current] v= 6705.65 3 x 36.08 = 107.30 V. - source voltage and sturce current is 107.30v (2-4 is 36.08 A Power factor angle o a tant la | : ( 777 = 37.42° Power fauth at source = corda 0.79 lagging agging /