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The┬а speed of a synchronous motor can be changed by changing ___________.
Supply Voltage
Supply Frequency
Excitation
All of these
Supply Frequency
The correct answer is B) Supply Frequency. The speed of a synchronous motor is directly proportional to the supply frequency of the alternating current fed to it.
The correct answer is B) Supply Frequency. The speed of a synchronous motor is directly proportional to the supply frequency of the alternating current fed to it.
NsтАЛ=P120├ЧfтАЛ тАФ Synchronous speed of a motor
The speed of a synchronous motor can be calculated using the formula NsтАЛ=P120├ЧfтАЛ, where NsтАЛ is the synchronous speed in RPM, f is the supply frequency in Hz, and P is the number of poles in the motor. Therefore, by varying the supply frequency, the synchronous speed can also be adjusted.
The synchronous speed depends on the frequency and number of poles.
For a given motor, changing frequency changes speed.
Provides the ability to maintain constant speed under varying load conditions.
Efficient operation due to synchronization with the supply frequency.
Limited range of speed control due to reliance on supply frequency.
Changes in speed can lead to operational instability.
Used in industrial applications requiring precise speed control.
Applicable in power generation systems.
Standard value: The standard frequency in India is 50 Hz.
Option A is incorrect because changing the supply voltage doesn't directly affect the synchronous speed.
B is correct тАФ the synchronous speed of the motor is primarily controlled by adjusting the supply frequency.
In AC machines, remember the relationship between frequency and speed plays a critical role in design and control.