300 Important Three Phase Induction Motor MCQ Question and Answer | PDF Free Download
1.The no load current in an induction motor is ____in comparison to that of a power transformer.
- AMuch lower
- BMuch higher
- CSlightly less
- DSlightly more
2.In a 3-phase induction motor, the variable mechanical load is represented electrically by a variable ____only
- AInductance
- BCapacitance
- CResistance
- DAny of these
3.If the load on an induction motor is increased from no load to full load, its slip and the power factor will, respectively
- ADecrease, decrease
- BDecrease, increase
- CIncrease, decrease
- DIncrease, increase
4.The output power of a 3-phase induction motor will be maximum when the equivalent load resistant is equal to the standstill leakage _____of the motor
- AImpedance Z
- BReactance X
- CResistance
- DCapacitance
5.The power factor of an induction motor operating at no load will have a value around
- A0.9 lag
- B0.2 lead
- C0.2 lag
- D0.9 lead
6.The power factor of an induction motor at full load is likely to be
- AUnity
- B0.85 lead
- C0.85 lag
- D0.5 lag
7.The power factor of a 3-phase induction motor is likely to be maximum when it will operate at
- AFull load
- BNo-load
- CMaximum slip
- DMaximum torque
8.The power factor of a lightly loaded induction motor is quite low because
- AThe current drawn is largely a magnetizing current due to air gap
- BOf the current due to air gap
- CThe current drawn is largely a magnetizing component due to laminated core
- DThe current drawn is largely an energy component due to laminated core
9.When the load is increased from light load in a 3-phase induction motor,
- ARotor pf increases but stator pf decreases
- BStator pf increases but the rotor pf decreases
- CBoth stator and rotor pf increase
- DBoth stator and rotor pf decrease
10.An induction motor always operators on lagging power factor this is due to
- AStator reactance
- BRotor leakage reactance
- CThe large reactive lagging magnetizing current essential to produce the magnetic flux
- DAll of the above
11.Open circuit test is usually conducted on which type of induction motor?
- ASlip ring motors
- BWound rotor motors
- CEither of (a) and (b)
- DNone of these
12.In which of the following tests to be conducted on induction motors, reduced voltage is applied
- ABlocked rotor test
- BNo load test
- CBoth (a) and (b)
- DNone of these
13.Blocked rotor test of an induction motors corresponds, in case of a transformer to
- AFull load
- BHalf full load
- CNo load
- DShort circuit operation
14.What is the shunt resistance component in equivalent circuit obtained by no-load test of an induction motor representative of?
- AWindage and frictional losses only
- BCore losses only
- CCore, windage and frictional losses
- DCopper losses
15.Under no-load condition, if the applied voltage to an induction motor is reduced from the rated voltage to half the rate value
- AThe speed decrease and the stator current increases
- BBoth the speed and the stator current decrease
- CThe speed and the stator current remain practically constant
- DThere is negligible changes in the speed but the stator current decreases
16.The core losses, and friction and windage losses in case of an induction motor are determine from the _____test
- ANo load
- BBlocked rotor
- CLoad
- DStator resistance
17.Short circuit test is performed on an induction motor to determine
- AShort-circuit current under rated voltage
- BEquivalent resistance and reactance
- CTransformation ratio and Power factor on short circuit
- DAll of the above
18.Circle diagram is employed to determine the performance of a
- ASynchronous motor
- BInduction motor
- CDC motor
- DTransformer
19.The power scale of circle diagram of an induction motor is determined from ____test data only.
- AOpen circuit
- BStator resistance
- CShort circuit
- DSlip
20.In the circle diagram of an induction motor the diameter of the circle represents the
- ARotor current
- BLine voltage
- COperating torque
- DMaximum torque