Question

The following readings were taken during an open-circuit test and short-circuit test on a three-phase, 10 MVA, 13.8 kV, 50 Hz synchronous generator driven at rated speed. Open Circuit Test Field Current 150 A 180 A 200 A 250 A 300 A 350 A Line voltage 11.2 kV 12.0 kV 12.5 kV 13.5 kV 14.3 kV 14.8 kV Short Circuit Test Field Current 150 A 180 A Short Circuit Current 400 A 480 A a) Plot the open-circuit and short-circuit characteristics on the same graph and determine the saturated synchronous reactance of the generator. b) If the generator delivers rated kVA to a load at rated voltage and 0.8 pf lagging, use the saturated synchronous reactance to determine the required excitation voltage E and load angle d. c) If the generator excitation is reduced to 80% of its value in part b), find the new load angle assuming the real power is unchanged.

Answer 1