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A 3 phase induction motor is fed by a 3 phase ac regulator to change the stator voltage. The variation in speed will be more if
- a)load torque is constant
- b)load torque increases with increase in speed
- c)load torque decreases with increase in speed
- d)either (a) or (b)
Correct answer is option 'B'. Can you explain this answer?
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Verified Answer
A 3 phase induction motor is fed by a 3 phase ac regulator to change t...
If load torque is constant, the change in speed is very small.
Most Upvoted Answer
A 3 phase induction motor is fed by a 3 phase ac regulator to change t...
Explanation:
When a 3-phase induction motor is fed by a 3-phase AC regulator to change the stator voltage, the variation in speed will be more if the load torque increases with an increase in speed.
1. Load Torque:
Load torque is the torque required by the motor to drive the load. It depends on the mechanical characteristics of the load being driven. Load torque can either be constant, decrease with an increase in speed, or increase with an increase in speed.
2. Induction Motor Speed:
The speed of an induction motor depends on the frequency of the AC supply and the number of poles in the motor. The synchronous speed can be calculated using the formula:
Synchronous Speed (Ns) = (120 * Frequency) / Number of Poles
The actual speed of the motor is slightly less than the synchronous speed due to slip. The slip is the difference between the synchronous speed and the actual speed of the motor. The slip is directly proportional to the load torque.
3. Effect of Load Torque on Speed:
When the load torque increases with an increase in speed, it means that as the motor tries to run faster, the load puts more resistance, requiring higher torque. In this case, if the stator voltage is reduced using the AC regulator, the available torque will be insufficient to meet the load torque. As a result, the motor will slow down and the speed variation will be more.
On the other hand, if the load torque is constant or decreases with an increase in speed, reducing the stator voltage using the AC regulator will result in a decrease in torque requirement. The motor will be able to meet the load torque even with reduced voltage, and the speed variation will be less.
4. Conclusion:
In conclusion, when a 3-phase induction motor is fed by a 3-phase AC regulator to change the stator voltage, the variation in speed will be more if the load torque increases with an increase in speed. This is because the motor will not be able to provide sufficient torque to meet the load requirements at lower voltages, causing the motor to slow down.
When a 3-phase induction motor is fed by a 3-phase AC regulator to change the stator voltage, the variation in speed will be more if the load torque increases with an increase in speed.
1. Load Torque:
Load torque is the torque required by the motor to drive the load. It depends on the mechanical characteristics of the load being driven. Load torque can either be constant, decrease with an increase in speed, or increase with an increase in speed.
2. Induction Motor Speed:
The speed of an induction motor depends on the frequency of the AC supply and the number of poles in the motor. The synchronous speed can be calculated using the formula:
Synchronous Speed (Ns) = (120 * Frequency) / Number of Poles
The actual speed of the motor is slightly less than the synchronous speed due to slip. The slip is the difference between the synchronous speed and the actual speed of the motor. The slip is directly proportional to the load torque.
3. Effect of Load Torque on Speed:
When the load torque increases with an increase in speed, it means that as the motor tries to run faster, the load puts more resistance, requiring higher torque. In this case, if the stator voltage is reduced using the AC regulator, the available torque will be insufficient to meet the load torque. As a result, the motor will slow down and the speed variation will be more.
On the other hand, if the load torque is constant or decreases with an increase in speed, reducing the stator voltage using the AC regulator will result in a decrease in torque requirement. The motor will be able to meet the load torque even with reduced voltage, and the speed variation will be less.
4. Conclusion:
In conclusion, when a 3-phase induction motor is fed by a 3-phase AC regulator to change the stator voltage, the variation in speed will be more if the load torque increases with an increase in speed. This is because the motor will not be able to provide sufficient torque to meet the load requirements at lower voltages, causing the motor to slow down.
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A 3 phase induction motor is fed by a 3 phase ac regulator to change the stator voltage. The variation in speed will be more ifa)load torque is constantb)load torque increases with increase in speedc)load torque decreases with increase in speedd)either (a) or (b)Correct answer is option 'B'. Can you explain this answer?
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