Choose the correct statement regarding two watt-meter method for power measurements in 3-phase circuit.

Power can be measured using two watt-meter method only for star connected 3-phase circuit

When power factor is unity, one of the wattmeters reads zero

When the readings of the two watt-meters are equal but opposite sign, the power factor is zero

Power can be measured using two watt-meter method only for star connected 3-phase circuit

When two watt-meters show identical readings, the power factor is 0.5

The two-wattmeter method is used to measure active power. The system is a 3-phase, 3- wire system. Then, the power reading is?

Affected by both negative sequence and zero sequence voltages

Affected by negative sequence voltages but not by zero sequence voltages

Affected by zero sequence voltages but not by negative sequence voltages

Not affected by negative or zero sequence voltages

Explore topic-wise MCQs in Electrical Measurements.

This section includes 8 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Measurements knowledge and support exam preparation. Choose a topic below to get started.

1.	In the measurement of 3-phase power by 2 watt-meter method, if the 2 watt-meter readings are equal, the power factor of the circuit is?
A.	0.8 lagging
B.	0.8 leading
C.	Zero
D.	Unity
Answer» E.

Discussion

2.	The meter constant of a single-phase, 230 V induction watt-meter is 600 rev/kW-h. The speed of the meter disc for a current of 15 A at 0.8 power factor lagging will be?
A.	30.3 rpm
B.	25.02 rpm
C.	27.6 rpm
D.	33.1 rpm
Answer» D. 33.1 rpm

Discussion

3.	Choose the correct statement regarding two watt-meter method for power measurements in 3-phase circuit.
A.	When power factor is unity, one of the wattmeters reads zero
B.	When the readings of the two watt-meters are equal but opposite sign, the power factor is zero
C.	Power can be measured using two watt-meter method only for star connected 3-phase circuit
D.	When two watt-meters show identical readings, the power factor is 0.5
Answer» C. Power can be measured using two watt-meter method only for star connected 3-phase circuit

Discussion

4.	The ratio of the reading of 2 watt-meters connected to measure power in a balanced 3-phase load is 2: 1 and the load is inductive. The power factor of load is?
A.	0.866 lag
B.	0.615 lead
C.	0.866 lead
D.	0.625 lag
Answer» B. 0.615 lead

Discussion

5.	The two-wattmeter method is used to measure active power. The system is a 3-phase, 3- wire system. Then, the power reading is?
A.	Affected by both negative sequence and zero sequence voltages
B.	Affected by negative sequence voltages but not by zero sequence voltages
C.	Affected by zero sequence voltages but not by negative sequence voltages
D.	Not affected by negative or zero sequence voltages
Answer» E.

Discussion

6.	A single-phase load is connected between R and Y terminals of a 220 V, symmetrical, 3-phase, 4 wire systems with phase sequence RYB. A watt-meter is connected in the system. The watt-meter will read (pf = 0.8 lagging)?
A.	795 W
B.	168 W
C.	+ 597 W
D.	+ 795 W
Answer» C. + 597 W

Discussion

7.	Power flowing in 3-phase, 3-wire system is measured by two wattmeter whose readings are 7000 W and -2500 W. if the voltage of the circuit is 400 V, then what will be the value of capacitance introduced in each phase to make one wattmeter reads zero? The frequency is 50 Hz.
A.	500 F
B.	668.6 F
C.	1000 F
D.	748.5 F
Answer» C. 1000 F

Discussion

8.	Two watt meters, which are connected to measure the total power on a three-phase system supplying a balanced load, read 10.5 kW and 2.5 kW respectively. What is the total power?
A.	13.0 kW
B.	13.0 kW
C.	8.0 kW
D.	8.0 kW
Answer» E.

Discussion

Explore topic-wise MCQs in Electrical Measurements.

In the measurement of 3-phase power by 2 watt-meter method, if the 2 watt-meter readings are equal, the power factor of the circuit is?

The meter constant of a single-phase, 230 V induction watt-meter is 600 rev/kW-h. The speed of the meter disc for a current of 15 A at 0.8 power factor lagging will be?

Choose the correct statement regarding two watt-meter method for power measurements in 3-phase circuit.

The ratio of the reading of 2 watt-meters connected to measure power in a balanced 3-phase load is 2: 1 and the load is inductive. The power factor of load is?

The two-wattmeter method is used to measure active power. The system is a 3-phase, 3- wire system. Then, the power reading is?

A single-phase load is connected between R and Y terminals of a 220 V, symmetrical, 3-phase, 4 wire systems with phase sequence RYB. A watt-meter is connected in the system. The watt-meter will read (pf = 0.8 lagging)?

Power flowing in 3-phase, 3-wire system is measured by two wattmeter whose readings are 7000 W and -2500 W. if the voltage of the circuit is 400 V, then what will be the value of capacitance introduced in each phase to make one wattmeter reads zero? The frequency is 50 Hz.

Two watt meters, which are connected to measure the total power on a three-phase system supplying a balanced load, read 10.5 kW and 2.5 kW respectively. What is the total power?