The oscillation in a synchronous motor can be damped out by ___

Electrical Engineering MCQ Electrical Machines MCQ
1

The oscillation in a synchronous motor can be damped out by

A. running the motor on leading power factors.
B. providing damper bars in the rotor pole faces.
C. oscillation cannot be damped.
D. maintaining constant excitation.

Show Answer

Answer: C

Share your understanding of this question with the correct explanation.

2

The answer is C. oscillation cannot be damped.

Oscillation in a synchronous motor cannot be damped. Synchronous motors are designed to run at a constant speed, and any deviation from this speed will cause the motor to lose synchronism and stall.

Here are some of the reasons why oscillation cannot be damped in a synchronous motor:

  • The rotor of a synchronous motor is made of a solid steel bar, which does not have any eddy current damping.
  • The stator of a synchronous motor is made of laminated steel, which does have eddy current damping, but this damping is not enough to prevent oscillation.
  • The synchronous motor is not designed to have any mechanical damping.

There are a few things that can be done to reduce the amount of oscillation in a synchronous motor, but these measures will not completely eliminate it. These measures include:

  • Maintaining constant excitation: This will help to keep the motor running at a constant speed.
  • Using damper bars: Damper bars are short-circuited conductors that are placed on the rotor of the motor. They help to dissipate the energy of any oscillations that do occur.
  • Using a soft starter: A soft starter is a device that can be used to gradually increase the speed of a motor. This can help to prevent sudden changes in speed that can cause oscillation.

Despite these measures, it is still possible for synchronous motors to experience oscillation. If this occurs, it is important to take steps to correct the problem. This may involve adjusting the motor’s excitation, adding damper bars, or using a soft starter.