Energy Meter MCQs

21. The energy meter installed at the residence charges the consumer for the use of

1. Apparent power
2. True power
3. Reactive power
4. Product of voltage and current

22. In energy meter, the braking torque is produced to

1. Safeguard it against creep
2. Break the instrument
3. Bring energy meter to a standstill
4. Maintain steady speed and equal to driving torque

23. Creeping in a single-phase induction type energy meter may be due to?

1. Overvoltage
2. Vibrations
3. Overcompensation for friction
4. All of the given options

24. A single-phase 230V energy meter has a constant load of 5 A passing through it for 6 hours was at unity power factor. If the meter disc makes 2070 revolutions during this period, what is the meter constant in revolutions per unit?

1. 100 rev/unit
2. 200 rev/unit
3. 300 rev/unit
4. 400 rev/unit

25. An energy meter is designed to make 100 revolutions for one unit of energy. Calculate the number of revolutions made by it when connected to load carrying 50 A at 230V and 0.6 power factor an hour.

1. 575 revolutions
2. 1150 revolutions
3. 920 revolutions
4. 690 revolutions

26. An energy meter is designed to make 100 revolutions for one unit of energy. The number of revolution when connected to a load of 40A, at 230V and 0.95 power factor lagging for an hour is

1. 657
2. 874
3. 362
4. 530

27. A single-phase energy meter has a constant of 1200 revolutions/kWh. When a load of 200 W is connected, the disc rotates at 4.2 revolutions per minute. If the load is on for 10 hours, the meter records an excess of

1. 0.1 kWh
2. 0.2 kWh
3. 1.0 kWh
4. 2.0 kWh

28. The meter constant of a single-phase energy meter is 500 rev/kWh. The metre takes 86 seconds to make 50 revolutions while measuring a full load of 4.4 kW. The percentage error in the meter is

1. -2.43%
2. 2.43%
3. -4.86%
4. 4.86%

29. In an induction type energy meter, everything else remaining same, if the radial distance of the brake magnet poles from the spindle is decreased by 10%, the rotational speed of the disc will _______ approximately.

1. Increase by 23.5%
2. Decrease by 10.6%
3. Decrease by 19.4%
4. Increase by 11%

30. The voltage coil of a single phase house energy meter

1. is highly inductive
2. is highly resistive
3. is highly capacitive
4. has a phase angle equal to load power factor angle