A 50 Hz, 75 kVA, 24000/277 V, Y-connected, three-phase distribution transformer produced the following test results:
Open circuit test: The test was performed on the low voltage side of this transformer, and the following data was recorded:
Voc = 277 V
Ioc = 7.10 A
Poc = 945 W
Short circuit test: The test was performed on the high voltage side of this transformer, and the following data was recorded:
Vsc = 2771 V
Isc = 1.15 A
Psc = 1140 W
Using this information, answer the following questions:
2.1 Determine the parameters of the equivalent circuit, referred to the high voltage side, and draw the equivalent circuit of this transformer.
2.2 Determine the voltage regulation at the rated load and 0.8 p.f. lagging. Repeat your calculation for the following transformer loadings and fill the table below:
Loading(%) | 0 | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 100
VR(%)
Sketch the characteristic showing the variation of voltage regulation versus transformer loading. Discuss your results.
2.3 Determine the transformer efficiency at rated load and 0.8 p.f. lagging. Repeat your calculation for the following transformer loadings and fill the table below:
Loading(%) | 0 | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 100
Efficiency(%)
100
