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

This Section covers below lists of topics.

1. Power Factor Meter
2. Frequency Meter
3. Synchroscopes
4. Phase Sequence Indicators

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• ±2%
• ±3%
• ±1%
• -1%

#### 2. The controlling torque in single phase power factor meter is provided by :

• Spring control
• Gravity control
• Stiffness of suspension
• None of the above.

#### 3. There will be serious errors, if power factor of non-sinosoidal waveform is measured by electrodynamometer power factor meters. This is true of :

• Only single phase meters
• Only three phase meters
• Both single and three phase meters
• None of the above.

#### 4. In a reed type frequency meters all the reeds :

• Have the same natural frequency
• Have different natural frequency
• Have different natural frequency but the difference in natural frequencies of adjacent reeds is ±0.5Hz.
• None of the above.

#### 5. A 53 Hz reeds type frequency meter is polarized with d.c. the new range of frequency meter is :

• 106 Hz
• 26.5 Hz
• 53 Hz
• None of the above.

#### 6. For a 3 phase, moving iron synchroscope F2= frequency of incoming machine F1= frequency of busbars   At equilibrium Φ = ±2πf’t + ɑ ; where f’ =  F2 - F1. If f’ is positive

• The incoming machine is faster
• The incoming machine is slower
• The incoming machine can be synchronized to the busbars
• None of the above.

#### 7. An electrodynamometers type of instrument is used in Weston type synchroscope while synchronizing an incoming machine to busbars

• For checking the power factor of the two circuits
• For checking the voltages of the two circuits
• For checking whether incoming machine is fast or slow
• For checking phase sequence of the two circuits.

#### 8. An alternator is being synchronized to the  busbars whose frequency is 50 Hz. The bulbs of the synchroscope  flickers at a frequency of 10 Hz. The frequency of the alternator is :

• 60 Hz
• 40Hz
• 60Hz or 40 Hz
• None of the above.

#### 9. A phase sequence indicator rotates clockwise for phase sequence of RYB. If the phase sequence is changed to BRY it will rotate

• Anticlockwise
• Clockwise
• Clockwise or anticlockwise
• None of the above.

#### 10. In a static type phase sequence indicator which uses two identical lamp of pure resistances in the circuit of phase R and Y and inductor in phase B having inductive reactance = resistance of bulb with circuit being connected in star. The reactance is equal to the bulb resistance. If bulb connected to phase R glows brightly and lamp connected to phase Y glows dimly, the phase sequence is :

• RBY
• RYB
• BRY
• None of the above.

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