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If the field of a synchronous motor is over excited, the power factor will be
Lagging
Leading
Zero
None of these
Leading
When a synchronous motor is overexcited, the excitation voltage exceeds the terminal voltage, resulting in a leading power factor ┬╖ This is because the motor behaves like a capacitor, drawing reactive power from the system.
When a synchronous motor is overexcited, the excitation voltage exceeds the terminal voltage, resulting in a leading power factor ┬╖ This is because the motor behaves like a capacitor, drawing reactive power from the system.
P=VтЛЕIтЛЕcos╧Х тАФ Power calculation in AC circuits
╧Г=VterminalтАЛQтАЛ тАФ Reactive power in terms of field strength
The overexcitation leads to an increase in the magnetic field strength within the motor, causing its current phase to lead the voltage phase ┬╖ This behavior corresponds to the absorption of reactive power, resulting in a leading power factor characteristic.
An overexcited synchronous motor operates with a leading power factor.
This characteristic enables such motors to supply reactive power to the grid, improving overall system efficiency.
Improves voltage regulation in power systems.
Increases system stability by providing reactive power support.
Risk of instability if improperly managed.
Excessive lead may cause voltage spikes in the network.
Used in synchronous condensers for power factor correction.
Applied in hydroelectric plants for grid stability.
The nominal operating power factor is critical for motor efficiency and can impact equipment lifespan.
Option A is incorrect as it describes the effect of underexcitation, whereas option C is irrelevant in this context.
B is correct тАФ When overexcited, synchronous motors exhibit a leading power factor due to the nature of their excitation levels.
Understanding motor excitation is crucial for electrical engineers, as it affects system stability and efficiency.