Hw4 - 18-418: Electric Energy Processing: Fundamentals and...

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18-418: Electric Energy Processing: Fundamentals and Applications Fall Semester, 2009 Homework # 4 Due on the class of September, 30 th Problem (1) A 150-MVA 15kV/200 kV single-phase power transformer has a per-unit resistance of 1.2 percent and a per unit reactance of 5 percent (data taken from the transformer’s nameplate). Neglect the core losses. a) Find the equivalent circuit referred to the low-voltage side of this transformer. b) Calculate the voltage regulation of this transformer for a full-load current at power factor of 0.8 lagging. c) Assume that the primary voltage of this transformer is a constant 15 kV, and plot the secondary voltage as a function of load current for currents from no-load to full- load. Repeat this process for power factors of 0.8 lagging, 1.0, and 0.8 leading. Problem (2) A three phase transformer connected in Δ -Y with total power is 25-kVA and per phase voltage is 24,000/277V. The open-circuit test as performed on the low-voltage side of this transformer bank, and the following data were recorded:
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This note was uploaded on 09/20/2010 for the course ECE 18418 taught by Professor Illic during the Fall '09 term at Carnegie Mellon.

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