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D.C. Generators - section-1
  1. Fleming's right-hand rule regarding direction of induced e.m.f., correlates

    2. A.

     Magnetic flux, direction of current flow and resultant force
    B.

     Magnetic flux, direction of motion and the direction of e.m.f. induced
    C.

     Magnetic field strength, induced voltage and current
    D.

     Magnetic flux, direction of force and direction of motion of conductor

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  2. Compensating windings are used in D.C. generators

    3. A.

     Mainly to reduce the eddy currents by providing local short-circuits
    B.

     To provide path for the circulation of cooling air
    C.

     To neutralize the cross-magnetizing effect of the armature reaction
    D.

     None of the above

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  3. Flashing the field of D.C. generator means

    4. A.

     Neutralizing residual magnetism
    B.

     Creating residual magnetism by a D.C. source
    C.

     Making the magnetic losses of forces parallel
    D.

     Increasing flux density by adding extra turns of windings on poles

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  4. In a separately excited generator supplying rated load the armature reaction:

    5. A.

     Is always present
    B.

     Is always absent
    C.

     May be sometimes present
    D.

     None of the above

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  5. If a D.C. generator fails to build up the probable cause could not be

    6. A.

     Imperfect brush contact
    B.

     Field resistance less than the critical resistance
    C.

     No residual magnetism in the generator
    D.

     Faulty shunt connections tending to reduce the residual magnetism

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  6. D.C. generators are connected to the bus-bars or disconnected from them only under the floating condition

    7. A.

     To avoid sudden loading of the prime mover
    B.

     To avoid mechanical jerk to the shaft
    C.

     To avoid burning of switch contacts
    D.

     All above

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  7. Two generators are running in parallel. One of the generators may run as motor for which of the following reasons?

    8. A.

     The direction of that generator is reversed
    B.

     The speed of that generator is increased
    C.

     The field of that generator is weakened
    D.

     That generator takes large share of loads

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  8. The function of pole shoes in the case of D.C. machine is

    9. A.

     To reduce the reluctance of the magnetic path
    B.

     To spread out the flux to achieve uniform flux density
    C.

     To support the field coil
    D.

     To discharge all the above functions

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  9. In case of a 4 pole D.C. generator provided with a two layer lap winding with sixteen coils, the pole pitch will be

    10. A.

     4
    B.

     8
    C.

     16
    D.

     32

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  10. For the parallel operation of two or more D.C. compound generators, we should ensure that

    11. A.

     Voltage of the incoming generator should be same as that of bus bar
    B.

     Polarity of incoming generator should be same as that of bus bar
    C.

     All the series fields should be run in parallel by means of equalizer connection
    D.

     Series fields of all generators should be either on positive side or negative side of the armature

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