Contents
What determines the speed of a synchronous motor?
The frequency of the power supply and the number of poles of the machine determine the synchronous speed. A synchronous motor is one in which the rotor turns at the same speed as the rotating magnetic field in the stator.
How do you speed up a synchronous motor?
Motors that are electronically controlled can be accelerated from zero speed by changing the frequency of the stator current. Very small synchronous motors are commonly used in line-powered electric mechanical clocks or timers that use the power line frequency to run the gear mechanism at the correct speed.
What is the relation between speed and frequency of induction motor?
The synchronous speed of the rotor in RPM N = 120f/P where f is the frequency of the stator current and P is the number of poles. The operating speed No = N – Ns where Ns is the slip speed. The frequency of the rotor current fr = Ns x P/120, so fr = 0 if the slip is zero.
Can you change the speed of a synchronous motor?
As you can see, the synchronous speed depends on the frequency of the supply and the number of poles of the rotor. Changing the number of poles is not easy, so we do not use that method. We can control the speed of the synchronous motor by changing the frequency of the supply to the motor.
What determines synchronous motors speed?
The synchronous speed for an electric induction motor is determined by the power supply frequency, and the number of poles in the motor winding.
Which is an example of a synchronous speed?
Example – Synchronous Speed of Electric Motor with Two Poles. A motor with two poles is supplied with power with frequency 50 Hz (1/s).
Which is better synchronous motor or induction motor?
Synchronous motors have fewer losses than induction motors at a given rating. Where, f = supply frequency and p = number of poles. As you can see, the synchronous speed depends on the frequency of the supply and the number of poles of the rotor. Changing the number of poles is not easy, so we do not use that method.
How is the speed of an AC motor determined?
Synchronous Speed The synchronous speed of an AC motor is determined by the frequency of the source and the number of poles. The RPM is calculated by multiplying the frequency times 60 and dividing by the number of pairs of poles. This was explained in Chapter 6.