Figure P3-4 shows a power system consisting of a three-phase 480-V 60-Hz generator supplying two loads...

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Figure P3-4 shows a power system consisting of a three-phase 480-V 60-Hz generator supplying two loads through a transmission line with a pair of transformers at either end. (a) Sketch the per-phase equivalent circuit of this power system. (b) With the switch opened, find the real power P, reactive power Q, and apparent power S supplied by the generator. What is the power factor of the generator? (c) With the switch closed, find the real power P, reactive power Q, and apparent power S supplied by the generator. What is the power factor of the generator? (d) What are the transmission losses (transformer plus transmission line losses) in this system with the switch open? With the switch closed? What is the effect of adding Load 2 to the system? off Generator 480 V 480/13,800 V 1000 KVA R = 0.010 pu X = 0.040 pu Line Z = 1.5+j100 Region 1 Shasel = 1000 KVA VL.basc2=480 V 13,800/480 V 500 KVA R=0.008 pu X = 0.040 pu Region 2 Shase21000 KVA VL.base2 = 13,800 V Load 1 ZLoad!= 0.5/36.87 2 Y-connected Load 2 ZLoad2= -j0.833 2 Y-connected Region 3 Shase3= 1000 KVA VL.base3 = 480 V Figure P3-4 shows a power system consisting of a three-phase 480-V 60-Hz generator supplying two loads through a transmission line with a pair of transformers at either end. (a) Sketch the per-phase equivalent circuit of this power system. (b) With the switch opened, find the real power P, reactive power Q, and apparent power S supplied by the generator. What is the power factor of the generator? (c) With the switch closed, find the real power P, reactive power Q, and apparent power S supplied by the generator. What is the power factor of the generator? (d) What are the transmission losses (transformer plus transmission line losses) in this system with the switch open? With the switch closed? What is the effect of adding Load 2 to the system? off Generator 480 V 480/13,800 V 1000 KVA R = 0.010 pu X = 0.040 pu Line Z = 1.5+j100 Region 1 Shasel = 1000 KVA VL.basc2=480 V 13,800/480 V 500 KVA R=0.008 pu X = 0.040 pu Region 2 Shase21000 KVA VL.base2 = 13,800 V Load 1 ZLoad!= 0.5/36.87 2 Y-connected Load 2 ZLoad2= -j0.833 2 Y-connected Region 3 Shase3= 1000 KVA VL.base3 = 480 V

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