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D.C. Motors - section-1
  1. In a D.C. series motor, if the armature current is reduced by 50%, the torque of the motor will be equal to

    2. A.

     100% of the previous value
    B.

     50% of the previous value
    C.

     25% of the previous value
    D.

     10% of the previous value

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  2. No-load speed of which of the following motor will be highest?

    3. A.

     Shunt motor
    B.

     Series motor
    C.

     Cumulative compound motor
    D.

     Differentiate compound motor

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  3. The power mentioned on the name plate of an electric motor indicates

    4. A.

     The power drawn in kW
    B.

     The power drawn in kVA
    C.

     The gross power
    D.

     The output power available at the shaft

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  4. If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor

    5. A.

     Of lower H.P. should be selected
    B.

     Of higher H.P. should be selected
    C.

     Can be used for 50°C ambient temperature also
    D.

     Is to be de-rated by a factor recommended by manufacturer and select the next higher H.P. motor

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  5. D.C. generators are normally designed for maximum efficiency around

    6. A.

     Full load
    B.

     Rated r.p.m.
    C.

     Rated voltage
    D.

     All of the above

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  6. In D.C. motor which of the following can sustain the maximum temperature rise?

    7. A.

     Slip rings
    B.

     Commutator
    C.

     Field winding
    D.

     Armature winding

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  7. In variable speed motor

    8. A.

     A stronger commutating field is needed at low speed than at high speed
    B.

     A weaker commutating field is needed at low speed than at high speed
    C.

     Same commutating field is needed at low speed than at high speed
    D.

     None of the above is correct

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  8. If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking

    9. A.

     Regenerative
    B.

     Plugging
    C.

     Dynamic braking
    D.

     None of the above

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  9. If a D.C. motor is to be selected for conveyors, which rriotor would be preferred ?

    10. A.

     Series motor
    B.

     Shunt motor
    C.

     Differentially compound motor
    D.

     Cumulative compound motor

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  10. For a D.C. shunt motor if the excitation is changed

    11. A.

     Torque will remain constant
    B.

     Torque will change but power will remain constant
    C.

     Torque and power both will change
    D.

     Torque, power and speed, all will change

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