141.  Which of the following statementsis correct regarding a 3-phase motor?
A. Its magnetic flux alternates at the supply frequency
B. It is cheap, robust and needs no skilled maintenance
C. Stator is externally connected rotor
D. Three-phase supply is usually connected to its rotor

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142.  The most important factor in motor maintenance is to keep
A. it clean and free from foreign materials
B. checking its insulation
C. regular check on line voltage
D. regular check of its lubrication

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143.  The two important parts of a 3-phase induction motor are
A. rotorand armature
B. rotor and stator
C. slip ring and brushes
D. stator and field

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144.  In a wound 3-phase induction motor, brushes should be connected to
A. external D.C. excitation ?
B. equilizing coils
C. power supply
D. external star-connected resistors

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145. Phase advancers are used with induction motors to
A. reduce noise
B. reduce vibrations
C. reduce copper losses
D. improve power factor

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146.  In a single phase motor the centrifugal switch
A. disconnects auxiliary winding of the motor
B. disconnects main winding of the motor
C. reconnects the main winding the motor
D. reconnects the auxiliary winding of the motor

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147.  The running winding of a single phase motor on testing with meggar is found to be ground. Most probable location of the ground will be
A. at the end connections
B. -t the end terminals
C. any where onthe winding inside a slot
D. at the slot edge where coil enters or comes out of the slot

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