Measurement of Power and Wattmeter MCQs - Electrical and Electronic Measurements

This Portion of Electrical andElectronic Measurements and Measuring instruments contains Measurement of Power and Wattmeter MCQs (Multiple Choice Questions and Answers) / Objective Type Questions and Answers.

This Section covers below lists of topics.

Power in D.C Circuits
Power in A.C Circuits
Electrodynamometer Wattmeters
Ferrodynamic Wattmeters
Low Power Factor Wattmeters
Thermocouple Wattmeters
Hall Effect Multiplier
Measurement of power using instrument transformers
Power in polyphase System
Measurement of power in Three phase circuits
Three phase Wattmeters
Measurement of Reactive Power

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1. The power in a d.c circuit is measured with the help of ammeter and a voltmeter. The voltmeter is connected on the load side.the power indicated by the product of reading of two instruments (VI) is :

The power consumed in the load
The sum of power consumed by the load and the voltmeter
The sum of power consumed by the load and ammeter
None of the above.

2. In an electrodynamometer type of wattmeter :

The current coil is made fixed
The pressure coil is fixed
Any of the two coil i.e current coil or pressure coil can be made fixed
Both the coil should be movable

3. In electrodynamometer type wattmeters, current coils designed for carrying heavy currents use stranded wire or laminated conductors :

To reduce iron losses
To reduce hysteresis losses
To reduce eddy current losses in conductors
All the above.

4. In electrodynamometer type of wattmeters , the inductance of pressure coil circuit produces error

Which is constant irrespective of the power factor of the load
Which is higher at low power factors
Which is lower at low power factors
None of the above.

5. A capacitor is connected across a portion of resistance of the multiplier in order to make the pressure coil circuit non-inductive. The value of resistance is r while the total resistance and inductance of pressure circuit are respectively R_p and L. The value of capacitor C is:

0.41L/r²
0.41L/(R_p)²
L/(R_p)²
L/r²

6. when measuring power with the electrodynamometer wattmeter in a circuit where the load current is small

the current coil should be connected on the load side
the pressure coil should be connected on the load side
it is immaterial whether current coil or pressure coil is connected on the load side.
None of the above.

7. when measuring power with the electrodynamometer wattmeter in a circuit where the load current is large

the current coil should be connected on the load side
the pressure coil should be connected on the load side
it is immaterial whether current coil or pressure coil is connected on the load side.
none of the above.

8. when measuring power with the electrodynamometer wattmeter in a circuit having a low power factor :

the current coil should be connected on the load side
the current coil should be connected on the supply side
the pressure coil should be connected on the load side
a compensated wattmeter with pressure coil connected on the load side should be used.

9. The power in a 3 phase four wire circuit can be measured by using

2 wattmeters
4 wattmeters
3 wattmeters
1 wattmeters

10. The power in 3 phase circuit is measured with the help of 2 wattmeters. The reading of the one of the wattmeters is positive and that of the other is negative. The magnitude of reading is different. it can concluded that the power factor of the circuit is :

Unity
Zero (lagging)
0.5 (lagging)
Less than 0.5 (lagging)

11. Power consumed by a simple dc circuit can be measured with the help of a single ammeter if

the load resistance is known
the supply voltage is known
both of (a) and (b) known
cannot be measured

12. Power indicated while measuring power in a dc circuit using an ammeter and a voltmeter, when the voltmeter is connected to the load side, is

true power consumed by the load
power consumed by the load plus power lost in ammeter
power consumed by the load plus power lost in voltmeter
power consumed by load plus power lost in both ammeter and voltmeter

13. In ammeter–voltmeter method for measurement of power in dc circuits, true power will be obtained with ammeter connected to the load side when

voltmeter has zero internal impedance
ammeter has zero internal impedance
ammeter has infinite internal impedance
voltmeter has infinite internal impedance

14. Electrodynamometer-type wattmeters have a construction where

current coil is fixed
voltage coil is fixed
both voltage and current coils are movable
both voltage and current coils are fixed

15. In electrodynamometer-type wattmeters, current coil is made of two sections

to reduce power loss
to produce uniform magnetic field
to prevent Eddy-current loss
to reduce errors due to stray magnetic field

16. In electrodynamometer-type wattmeters, current coils carrying heavy currents are made of stranded wire

to reduce iron loss
to reduce Eddy-current loss in conductor
to reduce hysteresis loss
all of the above

17. In electrodynamometer-type wattmeters, a high value noninductive resistance is connected in series with the pressure coil

to prevent overheating of the spring leading current in the pressure coil
to restrict the current in the pressure coil
to improve power factor of the pressure coil
all of the above

18. In electrodynamometer-type wattmeters, both current coil and pressure coil are preferably air-cored

to reduce effects of stray magnetic field
to reduce Eddy-current losses under AC operation
to increase the deflecting torque
all of the above

19. In electrodynamometer-type wattmeters, pressure coil inductance produce error which is

constant irrespective of load power factor
higher at low power factors of load
lower at low power factors of load
same at lagging and leading power factors of load

20. When measuring power in a circuit with low current, the wattmeter current coil should be connected

to the load side
to the source side
anywhere, either load side or source side, does not matter
in series with the load along with CT for current amplification

21. When measuring power in a circuit with high current

current coil should be connected to the load side
pressure coil should be connected to the load side
pressure coil should be connected to the source side
the placement of pressure and current coils are immaterial

22. In induction-type wattmeters,

voltage coil is the moving coil
current coil is the moving coil
both are moving
none are moving

23. Three wattmeters are used to measure power in a 3-phase balanced star connected load.

The reading will be higher when the neutral point is used as the common point for wattmeter pressure coils.
The reading will be lower when the neutral point is used as the common point for wattmeter pressure coils.
Wattmeter reading will remain unchanged irrespective whether the neutral is used for measurement or not.
The three-wattmeter method cannot be used in systems with 4 wires.

24. Two wattmeters can be used to measure power in a

three-phase four-wire balanced load
three-phase four-wire unbalanced load
three-phase three-wire unbalanced load
all of the above

25. In 2-wattmeter method for measurement of power in a star-connected 3 phase load, magnitude of the two wattmeter readings will be equal

at zero power factor
at unity power factor
at 0.5 power factor
readings of the two wattmeters will never be equal

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Electrical and Electronic Measurements – Measurement of Power and Wattmeter MCQs

1. The power in a d.c circuit is measured with the help of ammeter and a voltmeter. The voltmeter is connected on the load side.the power indicated by the product of reading of two instruments (VI) is :

2. In an electrodynamometer type of wattmeter :

3. In electrodynamometer type wattmeters, current coils designed for carrying heavy currents use stranded wire or laminated conductors :

4. In electrodynamometer type of wattmeters , the inductance of pressure coil circuit produces error

5. A capacitor is connected across a portion of resistance of the multiplier in order to make the pressure coil circuit non-inductive. The value of resistance is r while the total resistance and inductance of pressure circuit are respectively R_p and L. The value of capacitor C is:

6. when measuring power with the electrodynamometer wattmeter in a circuit where the load current is small

7. when measuring power with the electrodynamometer wattmeter in a circuit where the load current is large

8. when measuring power with the electrodynamometer wattmeter in a circuit having a low power factor :

9. The power in a 3 phase four wire circuit can be measured by using

10. The power in 3 phase circuit is measured with the help of 2 wattmeters. The reading of the one of the wattmeters is positive and that of the other is negative. The magnitude of reading is different. it can concluded that the power factor of the circuit is :

11. Power consumed by a simple dc circuit can be measured with the help of a single ammeter if

12. Power indicated while measuring power in a dc circuit using an ammeter and a voltmeter, when the voltmeter is connected to the load side, is

13. In ammeter–voltmeter method for measurement of power in dc circuits, true power will be obtained with ammeter connected to the load side when

14. Electrodynamometer-type wattmeters have a construction where

15. In electrodynamometer-type wattmeters, current coil is made of two sections

16. In electrodynamometer-type wattmeters, current coils carrying heavy currents are made of stranded wire

17. In electrodynamometer-type wattmeters, a high value noninductive resistance is connected in series with the pressure coil

18. In electrodynamometer-type wattmeters, both current coil and pressure coil are preferably air-cored

19. In electrodynamometer-type wattmeters, pressure coil inductance produce error which is

20. When measuring power in a circuit with low current, the wattmeter current coil should be connected

21. When measuring power in a circuit with high current

22. In induction-type wattmeters,

23. Three wattmeters are used to measure power in a 3-phase balanced star connected load.

24. Two wattmeters can be used to measure power in a

25. In 2-wattmeter method for measurement of power in a star-connected 3 phase load, magnitude of the two wattmeter readings will be equal

Electrical and Electronic Measurements – Measurement of Power and Wattmeter MCQs

1. The power in a d.c circuit is measured with the help of ammeter and a voltmeter. The voltmeter is connected on the load side.the power indicated by the product of reading of two instruments (VI) is :

2. In an electrodynamometer type of wattmeter :

3. In electrodynamometer type wattmeters, current coils designed for carrying heavy currents use stranded wire or laminated conductors :

4. In electrodynamometer type of wattmeters , the inductance of pressure coil circuit produces error

5. A capacitor is connected across a portion of resistance of the multiplier in order to make the pressure coil circuit non-inductive. The value of resistance is r while the total resistance and inductance of pressure circuit are respectively Rp and L. The value of capacitor C is:

6. when measuring power with the electrodynamometer wattmeter in a circuit where the load current is small

7. when measuring power with the electrodynamometer wattmeter in a circuit where the load current is large

8. when measuring power with the electrodynamometer wattmeter in a circuit having a low power factor :

9. The power in a 3 phase four wire circuit can be measured by using

10. The power in 3 phase circuit is measured with the help of 2 wattmeters. The reading of the one of the wattmeters is positive and that of the other is negative. The magnitude of reading is different. it can concluded that the power factor of the circuit is :

11. Power consumed by a simple dc circuit can be measured with the help of a single ammeter if

12. Power indicated while measuring power in a dc circuit using an ammeter and a voltmeter, when the voltmeter is connected to the load side, is

13. In ammeter–voltmeter method for measurement of power in dc circuits, true power will be obtained with ammeter connected to the load side when

14. Electrodynamometer-type wattmeters have a construction where

15. In electrodynamometer-type wattmeters, current coil is made of two sections

16. In electrodynamometer-type wattmeters, current coils carrying heavy currents are made of stranded wire

17. In electrodynamometer-type wattmeters, a high value noninductive resistance is connected in series with the pressure coil

18. In electrodynamometer-type wattmeters, both current coil and pressure coil are preferably air-cored

19. In electrodynamometer-type wattmeters, pressure coil inductance produce error which is

20. When measuring power in a circuit with low current, the wattmeter current coil should be connected

21. When measuring power in a circuit with high current

22. In induction-type wattmeters,

23. Three wattmeters are used to measure power in a 3-phase balanced star connected load.

24. Two wattmeters can be used to measure power in a

25. In 2-wattmeter method for measurement of power in a star-connected 3 phase load, magnitude of the two wattmeter readings will be equal

5. A capacitor is connected across a portion of resistance of the multiplier in order to make the pressure coil circuit non-inductive. The value of resistance is r while the total resistance and inductance of pressure circuit are respectively R_p and L. The value of capacitor C is: