The results obtained from open circuit and short circuit tests of a 20 kVA, 200/400 V, 50 Hz, single-phase transformer are given as follows:
Open circuit test:
- Voltage: 400V
- Current: 0.5A
- Power: 65W
Short circuit test:
- Voltage: 15V
- Current: 37.5A
- Power: 70W
Illustrate the equivalent circuit referred to the high-voltage side and determine the following:
i) Equivalent impedance of the transformer referred to the high-voltage side
ii) The voltage regulation at half-load conditions (0.8 p.f lagging)
Hence, sketch and label the phasor diagram of the transformer. (11 marks)