How Well Do You Know About Electrical Machines? Trivia Quiz
(269).jpg "How Well Do You Know About Electrical Machines? Trivia Quiz - Quiz")
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- 1.The basic function of a transformer is to change
- A.
The level of the voltage.
- B.
The power level.
- C.
The power factor.
- D.
The frequency.
- 2.Transformer is used
- A.
To step up the voltage.
- B.
To step down the voltage.
- C.
On dc.
- D.
To step up or step down the voltage.
- 3.An infinite bus-bar has
- A.
Constant voltage.
- B.
Constant frequency.
- C.
Infinite voltage.
- D.
Both A and B.
- E.
Both B and C.
- 4.Tappings of a transformer are provided
- A.
At the phase end of LV side.
- B.
At the phase end of HV side.
- C.
At the neutral end of HV side.
- D.
At the middle of HV side.
- 5.The auto-transformer is preferably employed in situations where voltage transformation ratio is
- A.
Very low.
- B.
Near unity.
- C.
Very high.
- D.
Unity.
- 6.An auto-transformer may be used as a/an ___________ transformer.
- A.
Power
- B.
Distribution
- C.
Automatically operated
- D.
Voltage regulating
- E.
Instrument
- 7.An auto-transformer has
- A.
One winding with taps taken out.
- B.
Two interlaced windings.
- C.
Two windings of same wire.
- D.
Two windings of different materials.
- E.
One winding without taps.
- 8.The principle of operation of a 3-phase induction motor closely resembles to that of a
- A.
Two winding transformer with its secondary short-circuited.
- B.
Two winding transformer with its secondary open-circuited.
- C.
Synchronous motor.
- D.
Dc shunt motor.
- 9.The relative speed between stator and rotor fluxes is equal to
- A.
Synchronous speed, Ns.
- B.
Rotor speed, N.
- C.
Zero
- D.
Ns-N
- 10.An induction motor works with
- A.
DC only.
- B.
AC only.
- C.
AC and DC both.
- D.
None of these.
- 11.The two important parts of an induction motor are
- A.
Stator and rotor.
- B.
Slip rings and brushes.
- C.
Core and winding.
- D.
Shaft and ball bearings.
- 12.When two alternators are operating in parallel, if the power input to one of the alternators is cut-off, the alternator will
- A.
Continue to run as a synchronous motor rotating in the same direction.
- B.
Continue to run as a synchronous motor rotating in opposite direction.
- C.
Stop running.
- D.
Get damaged due to burning of stator and rotor windings.
- 13.A 3-phase synchronous motor will not start if
- A.
Voltage is too low.
- B.
One phase is open.
- C.
Connections are faulty.
- D.
Any of the above.
- 14.Synchronous motors are inherently not self-starting motors as
- A.
The direction of instantaneous torque on the rotor reverses after each half cycle.
- B.
There is no slip.
- C.
The stator does not produce revolving magnetic field.
- D.
It has no starting winding.
- 15.Which of the following electric motors is not inherently self starting motor?
- A.
Synchronous motor.
- B.
3-phase induction motor.
- C.
Reluctance motor.
- D.
DC series motor.
- 16.In a synchronous motor, squirrel cage winding is provided for making motor
- A.
Noise free.
- B.
Self starting.
- C.
Cheap.
- D.
Quick start.
- 17.The method that can be used conveniently for speed control of a squirrel cage induction motor is
- A.
Pole changing control.
- B.
Rotor resistance control.
- C.
Cascade operation.
- D.
Secondary foreign voltage control.
- 18.If the prime-mover of an alternator supplying load to an infinite bus is suddenly shut down, then it will
- A.
Stop.
- B.
Continue to run as an alternator.
- C.
Continue to run as a synchronous motor in the reverse direction.
- D.
Continue to run as a synchronous motor in the same direction.
- 19.While starting a synchronous motor its field winding should be
- A.
Kept open.
- B.
Short-circuited.
- C.
Connected to a DC source.
- D.
None of the above.
- 20.Synchronous capacitor is
- A.
An ordinary static capacitor bank.
- B.
An over-excited synchronous motor driving mechanical load.
- C.
An over-excited synchronous motor without mechanical load.
- D.
None of the above.
- 21.When the induction motor is in standstill, the slip is
- A.
Zero.
- B.
1.
- C.
Infinity.
- D.
None of the above.
- 22.An electric motor gets over-heated. This may be due to
- A.
Over-loading.
- B.
Shorted stator winding.
- C.
Worn-out or dry bearings.
- D.
Low or high voltage.
- E.
Any of the above.
- 23.A squirrel cage induction motor is not favoured when _______________ is the main consideration.
- A.
Initial cost.
- B.
Maintenance cost.
- C.
High starting torque.
- D.
Higher efficiency and higher power factor.
- 24.Which of the following ac motor is widely used?
- A.
Squirrel cage induction motor.
- B.
Slip-ring induction motor.
- C.
Double cage induction motor.
- D.
Synchronous motor.
- 25.A slip-ring induction motor is recommended for applications requiring
- A.
High starting torque.
- B.
Variable speed operation.
- C.
Frequent starting, stopping and reversing operations.
- D.
All of the above features.
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