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Which of the following motor can operate on lagging as well as leading power factor?
DC series motor
Wound rotor induction motor
Squirrel cage induction motor
Synchronous motor
Synchronous motor
The correct answer is D) Synchronous motor. A synchronous motor can operate at both leading and lagging power factors, depending on the excitation of the rotor, thus providing enhanced control over reactive power.
The correct answer is D) Synchronous motor. A synchronous motor can operate at both leading and lagging power factors, depending on the excitation of the rotor, thus providing enhanced control over reactive power.
P=10003VphтАЛIphтАЛcos(╧Х)тАЛ тАФ Active Power in kW
Q=10003VphтАЛIphтАЛsin(╧Х)тАЛ тАФ Reactive Power in kVAR
Synchronous motors operate by locking the rotor speed with the synchronous speed of the rotating magnetic field produced by the stator. If the rotor is over-excited, it operates at a leading power factor, absorbing reactive power and providing it back to the grid. Conversely, if it is under-excited, it behaves like a lagging power factor motor, consuming reactive power.
Synchronous motors can control power factor by adjusting field excitation.
They are used in applications requiring precise speed and position control.
Can operate at unity or adjustable power factor.
High efficiency and good voltage regulation.
More complex control system compared to induction motors.
Higher initial cost.
Generators in power plants.
Large industrial drives requiring synchronized operations.
Synchronous motors are commonly used where duty cycle is much higher than that of induction motors.
Option A is incorrect as DC series motors operate only at unity power factor.
D is correct тАФ Synchronous motors uniquely allow for operating under both lagging and leading power factor conditions.
Understand the relationship between power factor and excitation levels, which is crucial for optimizing motor performance.