12-Final Exam Practice Problems

12-Final Exam Practice Problems - ELECTRICAL ENGINEERING...

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ELECTRICAL ENGINEERING DEPARTMENT California Polytechnic State University EE255 Practice Problems `````````````````````````````````````````````````````````````````````````````````````````````````````````````````` ```` Problem #1 A 100-KVA, 11,000:2,200-V, 60-Hz, single-phase transformer gave the following test results Voltage current power Open-circuit test: 2200V 1.59 A 980 W Short-circuit test: 580V 9.1 A 1100 w a) Determine the parameters of the approximate equivalent circuit referred to low-voltage side. b) Determine the voltage regulation of the transformer when supplying rated load at 2200 V and 0.8 power factor leading. [VR=-2.1%] c) Determine the all-day efficiency of the transformer for the following load cycle: 8 hours at rated load and .8 pf lagging, 8 hours at 80% full-load and 0.8 pf lagging, and 8 hours at 50% full-load and 0.8 pf lagging. The load is connected to the low voltage side. [Efficiency=97.4%] Problem #2 A 15-hp, three-phase, 8-pole, 440-V, 60-Hz, wound-rotor induction motor has its stator
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This note was uploaded on 12/19/2011 for the course EE 295 taught by Professor Alishaban during the Fall '11 term at Cal Poly.

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12-Final Exam Practice Problems - ELECTRICAL ENGINEERING...

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