This set of Network Theory Multiple Choice Questions & Answers (MCQs) focuses on “Power Measurement in Three-Phase Circuits”.

1. The wattmeter method is used to measure power in a three-phase load. The wattmeter readings are 400W and -35W. Find the power factor.

a) 0.43

b) 0.53

c) 0.63

d) 0.73

2. The wattmeter method is used to measure power in a three-phase load. The wattmeter readings are 400W and -35W. Find the reactive power.

a) 751.44

b) 752.44

c) 753.44

d) 754.44

3. The wattmeter method is used to measure power in a three-phase load. The wattmeter readings are 400W and -35W. Calculate the total active power.

a) 360

b) 365

c) 370

d) 375

4. The input power to a three-phase load is 10kW at 0.8 Pf. Two watt meters are connected to measure the power. Find the reading of higher reading wattmeter.

a) 7.165

b) 6.165

c) 6.165

d) 4.165

5. The readings of the two watt meters used to measure power in a capacitive load are -3000W and 8000W respectively. Calculate the input power. Assume RYB sequence.

a) 5

b) 50

c) 500

d) 5000

6. The wattmeter reading while measuring the reactive power with wattmeter is?

a) V_{L}I_{L}secØ

b) V_{L}I_{L}sinØ

c) V_{L}I_{L}tanØ

d) V_{L}I_{L}cosØ

7. The input power to a three-phase load is 10kW at 0.8 Pf. Two watt meters are connected to measure the power. Find the reading of lower reading wattmeter.

a) 1.835

b) 2.835

c) 3.835

d) 4.835

8. The readings of the two watt meters used to measure power in a capacitive load are -3000W and 8000W respectively. Find the power factor.

a) 0.25

b) 0.5

c) 0.75

d) 1

9. The total reactive power in the load while measuring the reactive power with wattmeter is?

a) √3V_{L}I_{L}cosØ

b) √3V_{L}I_{L}tanØ

c) √3V_{L}I_{L}sinØ

d) √3 V_{L}I_{L}secØ

10. A single wattmeter is connected to measure the reactive power of a three-phase, three-wire balanced load. The line current is 17A and the line voltage is 440V. Calculate the power factor of the load if the reading of the wattmeter is 4488 VAR.

a) 0.6

b) 0.8

c) 1

d) 1.2