Sage-Tips

Can a induction motor be used as a synchronous motor?

An Induction Motor is also known as Asynchronous Motor. It is so called because it never runs at synchronous speed.

Is it possible to run an induction motor at synchronous speed?

The Induction Motor cannot run at Synchronous speed because the Slip is never zero in an Induction Motor.

What happens when an induction motor is connected to a synchronous machine?

When the synchronous motor is starting, the torque will be produced by the induced current in the damping winding, so it can start as an induction motor. In addition, the damper winding has another function to help keeping the synchronous motor in synchronism.

Why is it impossible for an induction motor to operate a synchronous speed?

The induction motor can’t run at synchronous speed because it is not possible to run the motor without load. Even the motor is at no load, there would be core loss,copper loss and air friction loss.In a nut shell, the motor slip can not be zero in any case.

Which is better induction motor or synchronous motor?

The power factor of a synchronous motor can be adjusted to lagging, unity or leading by varying the excitation, whereas, an induction motor always runs at lagging power factor. Synchronous motors are generally more efficient than induction motors.

Where are synchronous motors used?

In the fractional horsepower range, most synchronous motors are used where precise constant speed is required. These machines are commonly used in analog electric clocks, timers and other devices where correct time is required. In higher power industrial sizes, the synchronous motor provides two important functions.

When induction motor runs over synchronous speed what runs?

If an external mechanical system drives the rotor above synchronous speed, the induction machine acts as a generator. If the rotor is rotating below synchronous speed, the induction machine is a motor.

What is difference between induction motor and synchronous motor?

The fundamental difference between these two motors is that the speed of the rotor relative to the speed of the stator is equal for synchronous motors, while the rotor speed in induction motors is less than its synchronous speed. When the stator and rotor fields lock together, the motor is now synchronous.

Why are induction motor called asynchronous?

Because it runs at a speed less than synchronous speed. Because induction motor can not rotate at synchronous speed it always rotate less than synchronous speed. in short, induction motor never rotates at synchronous speed so it called asynchronous motor.

In what way synchronous motor is different from other motors?

The power factor of a synchronous motor can be adjusted to lagging, unity or leading by varying the excitation, whereas, an induction motor always runs at lagging power factor. Synchronous motors are generally more efficient than induction motors. Synchronous motors are costlier.

What is the difference between synchronous AC and induction motors?

In contrast, consider a synchronous motor. Here, the rotor turns at the same rate — that is, in synchronization — as the stator’s magnetic field. Like the induction motor, the synchronous ac motor also contains a stator and a rotor.

How does a non-excited synchronous motor work?

Non-excited synchronous motors have steel rotors. In operation, the rotor is magnetized with the required magnetic poles in a manner analogous to that of an induction motor. But the rotor turns at the same speed and in synch with the stator rotating magnetic field. The reason is there are slots in the rotor.

How does an induction motor work electrically?

Once the rotor reaches final speed, the rotor poles get switched to a short circuit, thus becoming electrically the same as a squirrel cage rotor. The stationary part of the induction motor windings (stator) connects to the ac supply. Applying a voltage to the stator causes an ac current to flow in the stator windings.

How does the rotor of a synchronous motor work?

The rotor winding in a synchronous motor may receive current in a variety of ways, but usually not by induction (except in some designs, only to provide start-up torque). The fact that the rotor turns in synch with the ac line frequency makes the synchronous motor useful for driving highly-accurate clocks.