why do we use UPF watt meter in short circuit test of the
transformer and LPF watt meter in open circuit test of the
transformer

Answer Posted / abhishek

if you calculate the power factor in the no load test conducted you will get a lower value (.2 to .5). In blocked rotor test or in load test the power factor will be usually higher if you calculate (around 0.7 to 0.8). So we use lpf and upf wattmeter respectively.

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