ECE 4501 Power Systems UMD Spring 2003

QUIZ 4:

A single-phase transformer has the following nameplate data:

Primary Voltage Rating: 7200 Volts

Secondary Voltage Rating: 240 Volts

Capacity: 100 KVA

Under short-circuit testing, the transformer produces the following test data:

Vsc	Isc	Psc
506 Volts	13.89 Amps	1100 Watts

Under open-circuit testing, the transformer dissipates 450 Watts (Poc).

Find the following:

1. Ignoring the core, find the percent impedance of the transformer, on its own base.
2. Calculate the efficiency of the transformer for a 110 KVA load at a power factor of 0.75, lagging.
3. Calculate the voltage regulation of the transformer at full load KVA, 0.9 pf leading.