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Measurements and Instrumentation
Which of the following statement is correct for two wattmeters method of power measurement in 3 phase circuit?
Power can be measured by this method only for star connected loads
When two wattmeters have equal readings power factor is 0.5.
When power factor is 1, one of the wattmeters readings is zero
When the two wattmeter read equal and opposite, p.f. is zero.
Correct Answer:
When the two wattmeter read equal and opposite, p.f. is zero.
Explanation:
When p.f. is zero, active power is zero and the two redaings are equal and opposite.
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