In a 3-phase power measurement by two wattmeter method the reading of one of the wattmeter was zero. The power factor of the load must be?

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Answer :

In a 3-phase power measurement by two wattmeter method the reading of one of the wattmeter was zero. The power factor of the load must be 0.5.

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Description : In a 3-phase power measurement by two wattmeter method, both the watt meters had identical readings. The power factor of the load was?

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Description : The torque produced in wattmeter is proportional to

Last Answer : A

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Description : The potential coil of a single phase dynamometer wattmeter has 4840 Ohm resistance. Voltage across the load is 220 V. With the potential coil connected on the load side, the meter indicates 100 W. Approximate percentage error due to wattmeter connection is (A) 11% (B) 9% (C) 1.1% (D) 3%

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Description : Merits of two wattmeter method

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Description : List one advantage and one disadvantage of one wattmeter method. 

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Description : What is the power factor when a single phase watt meter operating on 200 V and 5 A for 5 hours makes 2016 revolutions and the meter constant in revolution is 420? A) 0.04 B) 1.04 C) 0.96 D) None of these

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Last Answer : The power factor of a single-phase induction motor is usually lagging.

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Last Answer : In an alternator, at lagging power factor the generated voltage per phase as compared to that at unity power factor must be more than terminal voltage.

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Description : State the principle of wattmeter. 

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Description : With neat diagram explain constructional details of dynamometer type wattmeter.

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Description : The power factor angle and torque angle of a salient pole synchronous generator drawing a current of 1.0 pu from a lagging load are 45o and 15o, respectively. The direct axis and quadrature axis currents, respectively, are (A) 0.5 pu ... pu, 0.5 pu (C) 0.707 pu, 0.707 pu (D) 0.5 pu, 0.5 pu

Last Answer : The power factor angle and torque angle of a salient pole synchronous generator drawing a current of 1.0 pu from a lagging load are 45o and 15o, respectively. The direct axis and quadrature axis currents, respectively, are 0.866 pu, 0.5 pu

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Last Answer : The power factor of a D.C. circuit is always unity.

Description : The ratio of active power to apparent power is known as____ factor.

Last Answer : The ratio of active power to apparent power is known as power factor.

Description : The input of an A.C. circuit having power factor of 0.8 lagging is 40 kVA The power drawn by the circuit is?

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Description : Power factor of electric bulb is?

Last Answer : Power factor of electric bulb is unity.

Description : The power factor at resonance in R-L- C parallel circuit is?

Last Answer : since a rlc circuit at resonance behaves like a pure resistive circuit, i.e there is no phase difference between current and voltage, hence the power factor is unity.

Description : Power factor of the system is kept high?

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