If the centrifugal switch does not open at 70 to 80 percent of the synchronous speed of the motor, it can

If the centrifugal switch does not open at 70 to 80 percent of the synchronous speed of the motor, it can

Right Answer is:

Damage to the starting winding

SOLUTION

  • A centrifugal switch is connected in series with the starting winding and placed inside the motor.
  • An auxiliary winding is for getting the motor started by providing initial torque and some phase differences are not made for running purposes.
  • Therefore it is advisable to disconnect the starting winding from the supply when the motor reaches 70 – 80% of its rated full-load speed otherwise it can damage the starting winding.
  • Important Reluctance Motor MCQ
  • Most of the troubles in single-phase induction motors are traceable to the centrifugal switch connected in series with the starting winding.
  • In normal use, the contact gap of the switch changes due to arcing and pitting.
  • If the starting switch fails to open when needed, the starting winding will almost always overheat and burn out. If the next attempt is made to start the motor. it will result in a growling sound and no rotation. This can cause the failure of the main winding unless the fuse blows out.
  • The centrifugal switch is necessary because most motors use an electrolytic capacitor that can only carry AC current for a short period.
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