Measurement MCQs Part-9

Measurement MCQs

Multiple choice questions on Measurement of power and energy

1. Which one of the following meters is an induction type instrument?

a. Multimeter

b. Energy meter

c. Voltmeter

d. Ammeter

 

2. The error caused by pressure coil inductance in a wattmeter is compensated by connecting a___________.

a. Capacitor in series with the inductor in the pressure coil circuit

b. Capacitor across a part of a series inductor in the pressure coil circuit

c. Capacitor in series with the series resistance in the pressure coil circuit

d. Capacitor across a part of series resistance in the pressure coil circuit

 

3. Power at RF is measured using________.

a. Voltmeter

b. Wattmeter

c. P = E²/R or P = I²R

d. Directly

 

4. Creeping in a single phase induction type energy meter may be due to_________.

a. Overvoltage or vibration

b. Neither overvoltage nor vibration

c. Vibration

d. Overvoltage

 

5. In a single phase induction type energy meter, the lag adjustment is done__________.

a. To make the pressure coil flux to lag 90^o behind the applied voltage

b. To make the current, coil flux to lag 90^o behind the applied voltage

c. To bring the pressure coil flux in phase with the applied voltage

d. None of the above

 

6. Phantom leading for testing of energy meter is used________.

a. To test meters having a large current rating for which load may not be available in the laboratory. This also reduce power losses during testing

b. To isolate the current and potential circuits

c. To reduce power loss during testing

d. For meters having low current ratings

 

7. The braking torque provided by a permanent magnet in a single phase meter is proportional to the__________.

a. Speed of the meter

b. Square of the flux of the permanent magnet

c. Both (a) and (b)

d. None of these

 

8. In an induction type energy meter, an increase in temperature results in__________.

a. An increase in angle of lag between V and potential coil flux Φ_p

b. An increase in the angle of lag 'α' of the eddy currents

c. A decrease in the resistance of the eddy current paths

d. A decrease in torque produced by all shading bands

 

9. In electrodynamometer type wattmeters, current coils designed for carrying heavy currents use stranded wire or laminated conductors________.

a. To reduce hysteresis losses

b. To reduce iron losses

c. To reduce eddy current losses in conductors

d. All of the above

 

10. In an electrodynamometer type wattmeters, the inductance of pressure coil circuit produces error __________.

a. Which is lower at low power factors

b. Which is higher at low power factors

c. Which is constant irrespective of the power factor of the load

d. All of the above

 

11. In an electrodynamometer type wattmeter_________.

1. Moving coil is iron cored

2. Fixed coil is air cored

3. Air friction damping is used

4. The fixed coil is connected across the load

5. The moving coil is connected in series with the load

a. 2 and 3 only

b. 1, 3, 4 and 5 only

c. 2, 4 and 5 only

d. 3 and 5 only

 

12. Holes are filled on the opposite side of the disc of an induction type energy meter to_________.

a. Increase the deflecting torque

b. Dissipate heat energy due to eddy currents

c. Balance the disc

d. Avoid creep on no-load