Why the speed of rotor must be less than speed of rotating magnetic field for the rotation of induction motor?

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In an induction motor, the speed of the rotor structure is always less than the speed of the stator field. … It is the relative motion between the rotor magnetic field and the stator windings that allows the magnetic field of the rotor to produce current in the stator.

Why is rotor speed less than synchronous speed in an AC induction motor?

Actual speed of the induction motor will be less than the synchronous speed. The reason for this is if the armature turns exactly at synchronous speed, then the magnetic field of the stator windings no longer cuts the rotor windings. … With no current flow in the armature, no magnetic field will be developed.

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Does the rotor of an induction motor rotate at the same speed as the rotating field?

After the motor attains maximum speed, DC is applied to the rotor coils. This creates a strong and ongoing magnetic field in the rotor that matches the rotating magnetic field. As a result, the rotor rotates at the same speed as the rotating magnetic field (or synchronous speed). Therefore, there is no slip.

Why does the speed of induction motor is always less than the synchronous speed?

The induction motor always runs at speed less than its synchronous speed. … Due to the lag between the flux current in the rotor and the flux current in the stator, the rotor will never reach its rotating magnetic field speed (i.e. the synchronous speed).

Why does the rotor of an induction motor turn slower than the revolving field?

If the rotor speed of Induction motor equals synchronous speed , then rotor won’t cut the flux by the stator, which is rotating at synchronous speed. Hence the rotor will stop rotating. Synchronous speed of the flux is determined by the formula Ns = 120*f/p . … The rotating magnetic field interact with the rotor bars.

Can induction motor run at synchronous speed?

So, theoretically, the Induction motor can never run at synchronous speed. … But due to the reduction of speed, again lag influx will be achieved, and the motor will continue to move at this speed due to flux difference between rotor and stator. In short, an induction motor cannot run at induction speed.

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What is the difference between synchronous speed and rotor speed?

Induction motor with squirrel cage rotor has two different speeds. The synchronous speed refers to the stator rotating magnetic field, which depends on the number of poles and frequency. The other speed is the rotor’s. The rotor speed will be always slower than the stator speed, we call it slip.

What force is needed to create rotation of the rotor?

The rotor is a moving component of an electromagnetic system in the electric motor, electric generator, or alternator. Its rotation is due to the interaction between the windings and magnetic fields which produces a torque around the rotor’s axis.

What happens if fifth harmonics is given to induction motor?

What happens if fifth multiples of harmonics is given to induction motor? It will rotates in reverse direction.

How a rotating flux is developed?

The rotating magnetic field is produced by the three-phase current of the stator in the actual three-phase induction motor. It can be replaced by permanent magnets in a permanent magnet synchronous motor. The three-phase windings of the inner stator are spaced 120° electrical degrees apart.

What is 120 in motor speed formula?

The equation for calculating synchronous speed is: S = 120 f/P speed = constant (120) times frequency of power source (60 Hz) divided by number of poles used in the motor (P).

What is synchronous speed of motor?

The synchronous speed is the speed of the revolution of the magnetic field in the stator winding of the motor. It is the speed at which the electromotive force is produced by the alternating machine.

Which braking is not possible in series motor?

Regenerative braking is not possible in a series motor. Explanation: In regenerative braking, the motor acts as a generator. The back emf is more than the terminal voltage in case of regenerative braking.

Why starters are used in induction motor?

Let us study in detail why starter is required for an induction motor. At starting time, the speed of the motor is zero and slip is at its maximum i.e. unity. So magnitude of the rotor induced emf is very large at start.

Which DC motor is preferred for constant speed?

Explanation: Rotary compressor generally demand constant speed operation throughout the load. Sometimes, DC machines are not able to produce constant speed throughout the process hence, synchronous machine is used. 4.

Which DC motor is used in elevator?

Which of these types of motor is used in elevators? DC series motor.