Measurement of Power MCQs

Welcome to our comprehensive collection of Multiple Choice Questions (MCQs) on Measurement of Power, a fundamental topic in the field of Electrical Measurement and Instrumentation. Whether you're preparing for competitive exams, honing your problem-solving skills, or simply looking to enhance your abilities in this field, our Measurement of Power MCQs are designed to help you grasp the core concepts and excel in solving problems.

In this section, you'll find a wide range of Measurement of Power mcq questions that explore various aspects of Measurement of Power problems. Each MCQ is crafted to challenge your understanding of Measurement of Power principles, enabling you to refine your problem-solving techniques. Whether you're a student aiming to ace Electrical Measurement and Instrumentation tests, a job seeker preparing for interviews, or someone simply interested in sharpening their skills, our Measurement of Power MCQs are your pathway to success in mastering this essential Electrical Measurement and Instrumentation topic.

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Measurement of Power MCQs | Page 10 of 11

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Q91.
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

Discuss
Answer: (b).When the readings of the two watt-meters are equal but opposite sign, the power factor is zero
Q92.
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

Discuss
Answer: (c).27.6 rpm
Q93.
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

Discuss
Answer: (d).Unity
Q94.
A coil (which can be modelled as a series RL circuit) has been designed for high Q performance. The voltage is rated at and a specified frequency. If the frequency of operation is increased 10 times and the coil is operated at the same rated voltage. The new value of Q factor and the active power P will be?

a.

P is doubled and Q is halved

b.

P is halved and Q is doubled

c.

P remains constant and Q is doubled

d.

P decreases 100 times and Q is increased 10 times

Discuss
Answer: (d).P decreases 100 times and Q is increased 10 times
Q95.
Two watt-meters, which are connected to measure the total power on a three-phase system supplying a balanced load, read 20.5 kW and -3.5 kW respectively. The total power is?

a.

13.0 kW

b.

17 kW

c.

15 kW

d.

19 kW

Discuss
Answer: (d).19 kW
Q96.
A circuit is used to measure the power consumed by the load. The current coil and the voltage coil of the watt-meter have 0.02 Ω and 1000 Ω resistances respectively. The measured power (as compared to the load power) will be?

a.

0.4 % less

b.

0.2 % less

c.

0.2 % more

d.

0.4 % more

Discuss
Answer: (c).0.2 % more
Q97.
A sampling watt-meter is used to measure the average power of a load. The peak to peak voltage of the square wave is 10 V and the current is a triangular wave of 5A p-p. The reading in watt will be?

a.

Zero

b.

25 W

c.

50 W

d.

100 W

Discuss
Answer: (a).Zero
Q98.
The line to line input voltage to the 3-phase, 50 Hz, AC circuit, is 100 V rms. Assuming that the phase sequence is RYB; the watt-meters would read?

a.

W₁ = 886 W and W₂ = 886 W

b.

W₁ = 500 W and W₂ = 500 W

c.

W₁ = 0 W and W₂ = 1000 W

d.

W₁ = 250 W and W₂ = 750 W

Discuss
Answer: (c).W₁ = 0 W and W₂ = 1000 W
Q99.
The meter constant of a single-phase, 100 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.

16 rpm

c.

12 rpm

d.

33.1 rpm

Discuss
Answer: (c).12 rpm
Q100.
A 3-phase, 600 V motor, the load having 0.6 power factor uses two watt-meter to measure the power. If the power measured be 45 kW, then the reading of each instrument will be?

a.

P₁ = 35 kW, P₂ = 10 kW

b.

P₁ = 47.25 kW, P₂ = -2.25 kW

c.

P₁ = 39.82 kW, P₂ = 5.179 kW

d.

P₁ = 45 kW, P₂ = 0 kW

Discuss
Answer: (c).P₁ = 39.82 kW, P₂ = 5.179 kW
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