A single-phase preventer continuously monitors and protects preferably which motor against phase failure?
3-phase induction motor
A single-phase preventer is a device used to monitor and protect three-phase motors, specifically the 3-phase induction motor, from phase failure or phase loss. Here's how and why:
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Concept of Phase Failure:
- Phase failure in a three-phase motor occurs when one of the supply phases is lost or is significantly lower in voltage than the other two.
- This results in unequal phase currents and can cause severe motor heating and damage due to unbalanced operation.
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Working of a Single-Phase Preventer:
- A single-phase preventer detects the loss of any phase or unbalanced condition in the supply.
- It then disconnects the motor from the power supply to prevent damage.
- Additionally, it may trigger an alarm or indicator signal to alert the operator of the fault condition.
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Why Other Motors are Not Monitored by Single-Phase Preventers:
- DC Motor: Operates on direct current; hence, phase failure does not apply.
- Reluctance Motor: Typically, single-phase or small three-phase, not often used in applications requiring phase failure prevention.
- Single-phase Induction Motor: Naturally operates on a single phase, so phase failure protection is not applicable.
Conclusion: Among the options provided, the 3-phase induction motor is the only one that requires a single-phase preventer for protection against phase failure. This makes it the correct answer.
Similar Questions
Which of the following is a key maintenance practice for reliable operation of a 3-phase induction motor?
If the frequency of an AC source is doubled, the impedance of a pure resistor ____________.
Which of the following sets of statements about the causes of errors in current transformers is correct?
i) Leakage reactance in secondary winding contributes to ratio error
ii) High magnetizing current increases phase angle error
iii) Burden with low power factor increases phase angle error
iv) Core saturation reduces both ratio and phase angle errors
Consider the following statements about torque in synchronous motors.
I. The torque in a synchronous motor is produced only when the rotor is locked into synchronism.
II. The torque is directly proportional to the sine of the load angle (δ).
III. Synchronous motor develops starting torque proportional to the power input.
IV. Maximum torque occurs at δ = 180°.
Which of the above statements are correct?
Important Questions from Three Phase Induction Motor
The stator of a 3-phase induction motor has 4 slots per pole phase. If the supply frequency is 50 Hz, calculate the number of stator poles produced and the total number of slots on the stator, respectively.
In an induction motor for a value slip(s) = 0, the torque (T) is
The stator of a 3-phase induction motor has 2 slots per pole per phase. If supply frequency is 50 Hz, then calculate the number of stator poles and total number of slots on the stator.
If all the stator coils of a motor are connected for the same magnetic polarity, there will be formed an equal number of ________.
The shaft of an induction motor is made of
