Measurement and Instrumentation Multiple Choice Questions and Answers for Practice

16. In a 3-phase power measurement by two wattmeter method, both the watt meters had identical readings. The power factor of the load was

1. unity
2. 0.8 lagging
3. 0.8 leading
4. zero

17. In a dynamometer 3-phase power factor meter, the planes of the two moving coils are at

1. 0°
2. 60°
3. 90°
4. 120°

18. In a low power factor wattmeter the compensating coil is connected

1. in series with current coil
2. in parallel with current coil
3. in series with pressure coil
4. in parallel with pressure coil

19. In a low power factor wattmeter the pressure coil is connected

1. to the supply side of the current coil
2. to the load side of the current coil
3. in any of the two meters at connection
4. none of the above

20. In a meggar controlling torque is provided by

1. spring
2. gravity
3. coil
4. eddy current

21. In a portable instrument, the controlling torque is provided by

1. spring
2. gravity
3. eddy currents
4. all of the above

22. In a Schering bridge the potential of the detector above earth potential is

1. a few volts only
2. 1 kV
3. 5 kV
4. 10 kV

23. In a single phase power factor meter the phase difference between the currents in the two pressure coils is

1. exactly 0°
2. approximately 0°
3. exactly 90°
4. approximately 90°

24. In a vibrating reed frequency meter the natural frequencies of two adjacent reeds have a difference of

1. 0.1 Hz
2. 0.25 Hz
3. 0.5 Hz
4. 1.5 Hz

25. In a Weston frequency meter, the magnetic axes of the two fixed coils are

1. parallel
2. perpendicular
3. inclined at 60°
4. inclined at 120°

26. In a Weston synchronoscope, the fixed coils are connected across

1. bus-bars
2. incoming alternator
3. a lamp
4. none of the above

27. In an AC. co-ordinate potentiometer, the currents in the phase and quadrature potentiometer are adjusted to be

1. out of phase by 90°
2. out of phase by 60°
3. out of phase by 30°
4. out of phase by 0°

28. In an Anderson bridge, the unknown inductance is measured in terms of

1. known inductance and resistance
2. known capacitance and resistance
3. known resistance
4. known inductance

29. In an energymeter braking torque is produced to

1. safe guard it against creep
2. brake the instrument
3. bring energy meter to stand still
4. maintain steady speed and equal to driving torque

30. In majority of instruments damping is provided by

1. fluid friction
2. spring
3. eddy currents
4. all of the above