How is a rotating magnetic field produced in a 3 phase induction motor?

The rotating magnetic field is produced by the three-phase current of the stator in the actual three-phase induction motor. … The three-phase windings of the inner stator are spaced 120° electrical degrees apart. In addition, the conductor of each winding is distributed such as a sinusoidal wave.

What is rotating magnetic field in 3-phase induction?

Leave a Comment / Three phase induction motor. The induction motor rotates due to the rotating magnetic field in induction motor, which is produced by the stator winding in the air gap between the stator and the rotor.

When a 3-phase supply is given to the winding a rotating magnetic field of magnitude is produced?

When we apply a three-phase supply to a three-phase distributed winding of a rotating machine, a rotating magnetic field is produced which rotates in synchronous speed.

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What is the speed of rotating magnetic field produced in the stator of 3ph induction motor?

In general, for P poles, the rotating field makes one revolution in P/2 cycles of current. The speed of the rotating magnetic field is the same as the speed of the alternator that is supplying power to the motor if the two have the same number of poles. Hence the magnetic flux is said to rotate at synchronous speed.

How does a rotating magnetic field work?

Description. The rotating magnetic field is the key principle in the operation of induction machines. … In the stator a group of fixed windings are so arranged that a two phase current, for example, produces a magnetic field which rotates at an angular velocity determined by the frequency of the alternating current.

What is the basic principle of 3-phase induction motor?

The stator of an induction motor consists of a number of overlapping windings offset by an electrical angle of 120°. When the primary winding or stator is connected to a three phase alternating current supply, it establishes a rotating magnetic field which rotates at a synchronous speed.

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.

What is the importance of slip in a 3-phase induction motor?

The slip increases with an increasing load, thus providing a greater torque. Originally Answered: What is the importance of slip in a 3-phase induction motor? Slip creates a relative speed between the RMF and rotor. That keeps a torque continuously acting on it when the motor is running.

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What is the magnitude of rotating magnetic field?

The magnitude of rotating magnetic field is given in terms of maximum mmf of any one phase when current in that phase is maximum. Let the this maximum mmf is Fm. In general, m-phase currents flowing in the m-phase winding results in a rotating mmf wave of constant amplitude equal to (m/2)Fm.

What is cogging and crawling?

The important characteristics normally shown by a squirrel cage induction motors are crawling and cogging. These characteristics are the result of improper functioning of the motor that means either motor is running at very slow speed or it is not taking the load.

How does an induction motor start?

A three-phase Induction Motor is Self Starting. When the supply is connected to the stator of a three-phase induction motor, a rotating magnetic field is produced, and the rotor begins rotating and the induction motor starts.

How can we adjust the speed of a rotating magnetic field?


Speed is important to the rotating magnetic field of an AC motor. It is known as “synchronous speed.” This speed is calculated by dividing 120 times the frequency (F) by the number of poles (P). As an example, the synchronous speed for a 2-pole motor operated at 60 Hz is 3,600 RPM.

What is the necessity of rotating magnetic field in induction motor?

The difference between the stator (synchronous speed) and rotor speeds is called the slip. The rotation of the magnetic field in an induction motor has the advantage that no electrical connections need to be made to the rotor.

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What are the advantage of rotation magnetic field?

For a large level of generation rotating field alternators are used. There is an advantage of rotating field alternator over rotating armature alternator. The advantage of having stationary armature winding is that the voltage can be directly connected to load and also we can insulate the conductor.

Which motor can develop a rotating magnetic field the easiest?

Induction motors only work on an AC supply (which reverses in direction 100 times per second), as this is how the stator can produce a rotating magnetic field. Since the frequency of the AC supply is fixed, you can’t easily vary the speed of an induction motor.

What are the factors that govern in the magnetic field rotation?

The rotating field speed depends on the number of magnetic poles in the stator and is referred to as the synchronous speed. Frequency refers to the power supply frequency (e.g. 60 Hz). The number of magnetic poles (or simply poles) is the principal design factor affecting speed in AC motors.