# How does AC synchronous motor work?

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A synchronous electric motor is an AC motor in which, at steady state, the rotation of the shaft is synchronized with the frequency of the supply current; the rotation period is exactly equal to an integral number of AC cycles. … The synchronous motor and induction motor are the most widely used types of AC motor.

## How is AC synchronous motor speed controlled?

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. Some motors are designed to operate at synchronous speed.

## Do AC synchronous motors have brushes?

Synchronous motors are AC motors. Scince rotor is rotating part we use slip rings and carbon brushes to give supply to the rotor. … Because the rotor turns at the same speed as synchronous speed (speed of the rotating magnetic field), there is no slip.

## Where are AC synchronous motors used?

Synchronous motors are normally used in applications in which a constant and precise speed is required. Typical applications of these low power motors are positioning machines. They are also used in robot actuators. Synchronous motors are also used in ball mills, watches, record players, and turntables.

## What is relation between synchronous speed and frequency?

The synchronous speed of the motor remains constant if the number of poles and the frequency are constant.

Synchronous speed Formula.

No. of Poles Frequency (50 Hz) Frequency(60 Hz)
2 3000 3600
4 1500 1800
6 1000 1200
8 750 900

## How do you know if a motor is synchronous?

To test the rotor for an open winding, connect one of the ohmmeter leads to each of the slip rings on the rotor shaft, Figure 17–5. Since the rotor winding of a synchronous motor is intended for DC current, the resistance of the wire will be high as compared with the wire resistance of a wound rotor motor.

## Are synchronous motors AC or DC?

In a synchronous motor, AC power is supplied to the stator to generate a rotating magnetic field. DC power is supplied to the rotor which results in discrete North (N) and South (S) poles.

## What is the main disadvantage of synchronous motors? 