Two similar 250/1000 Volts, 10 KVA Transformers are being tested by the sumpner's test method. At rated voltage of 250volts on the Low voltage side the wattmeter reading is found 250watts and ammeter reading is 4Ampers. On the series connected High voltage side, a voltage of 80Volts drives a rated full load current of 10 Amperes. Calculate the efficiency of the transformer at 80% of its full load at 0.9 Power factor leading?
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