Induction motor | Type of induction motor

Discussed here  Induction motorConduction motor, AC motor classification, stator induction motor Given in detail below

What is an induction motor?

The motor that operates based on Faraday's principle of electromagnetic induction is called an induction motor. Turns Based on the principle of induction, it is called an induction motor.
Electric power is usually supplied to induction motors through brushes and commutators.

But AC is supplied to the stator of the conduction motor. This creates a rotating magnetic field.

The rotor conductor intersects this rotating flux. According to Faraday's principle of electromagnetic induction, voltage is absorbed in the rotor.

The two ends of the rotor are shot, current flows for the induced voltage, and torque is generated in the rotor.

As a result, the stator magnet ball line starts rotating in the direction of the rotor. It is called an induction motor based on the principle of induction.

The speed of the rotor of this motor is always a little less than the synchronous speed. This is why another name for this motor is a synchronous motor.

This motor has two windings and windings, known as stator rotors.
In 1888, scientist Nicholas Tesla invented the induction motor.

Different types of ac motors or Type of ac motor

1. Synchronous motors



2. Asynchronous motors

    a.Squirrel cage

    b.Slip ring

3. Commutator motors
    a.Series (Single Phase and Universal)
    b.Compensated (Inductively and Inductively)
    c.Shunt (single and compensated)
    d.Repulsion (Straight and Compensated)
    e.Repulsion Start Induction
    f.Repulsion induction

According to speed

    a.Constant speed

    b.Variable speed

    c. Adjustable speed

According to the Structural



    c. Semi-enclosed


    f.Pipe ventilated

    g.Riveted frame eye

Induction motor type

There are two types of induction motors according to the supply method

1. Single-phase induction motor

2. Three-phase induction motor

Three types based on three-phase induction motor structure

There is no structural difference between single-phase and three-phase induction motors. The differences between single-phase and three-phase induction motors are as follows: -

1. Single phase induction motor stator single-phase supply is provided.

2. Sometimes, a centrifugal switch is used to disconnect the windings used for starting.

stator induction motor

The structure of the stator of the induction motor.

The stator of the induction motor is the largest and heaviest part. The structure depends on the size of the motor. It is divided into two parts.

One part is the cast iron frame or yoke. It is made very heavy and strong. It has two endplates on either side in which the shaft of the rotor on the ball bearing rotates at full load including the rotor.

The base plate has a foundation plate at the bottom to keep the frame of the motor firmly attached to the clouds. The second part of the stator is the stamping, which is made of a laminated silica steel sheet.

The thickness of each of the laminated sheets is about 0.5 mm. The sheets are insulated with each other. Loss is reduced as a result of using the laminated sheets.

The inside of the stamping has a groove or slot for the required winding. The shape of the stamping groove or slot can be of many types. How Semi-Closed, Closed, or Open Type.

The length, width, and depth of this slot depending on the motor's design and the amount of horsepower. The stator winding is similar to the stator winding of alternator and synchronous motors.

This is usually a full coil lap winding. It is of course three-phase winding.

At the time of winding, the calculation of each coil per phase and per pole has to be matched. Note that if more than one coil is required to make each pole, these coils are connected.

So that the circulating current does not flow between them for more or less the induced voltage in the coil. Insulation is very good in the coil group.

A three-phase induction motor's speed is proportional to the number of poles produced by the coil and proportional to the number of supplied frequencies.

So it can be seen that after reducing the high-speed motor in the same powered motor, 6 terminals are taken out to connect to the three-phase supply outside.

If necessary, the motor can be driven in Star or Delta Changing the position of any two phases in three phases changes the direction of rotation of the motor.

Motor air gap (air gap)

The main source of low power factor in air gap induction motors. Air gap magnetizing increases the amount of current and creates flux in the air gap.

This current stays at the lagging voltage. Therefore, to reduce these, the length of the air gap lens should be kept short.

However, the air gap cannot be reduced much because very few air gaps cause noise while the motor is running and the tooth-tace is lost. Can't even run at rated speed.

Rotating transformer

The induction motor is a rotating transformer. It basically works like the condition of the secondary short circuit of the transformer.

There is no rotating part of the transformer. But the induction motor has a rotating part. The stator of the induction motor acts as the primary coil and the rotor as the secondary coil.

Applying AC supply to a stator like a transformer causes rotating magnetic flux. Which crosses the air gas and cuts the motor inductor.

the speed control method of induction motor

1. The supply voltage of the motor increases or decreases
2. The frequency changes
3. Changes the old number of the stator
4. The rotor changes current and resistance

5. Cascade  control method

Method of testing induction motor

1.No load test
2. Block rotor test or load test
3. Stator resistance test

uses of electric motor

Induction motors are the most popular and popular among electric motors. The main reasons for the increase in popularity are the city structure of the motor, its practicality, ease of starting and stopping with little effort, easy control of speed and rotation.

Induction motors are almost all motors used in daily mills, from electric gadget motors to large mills, workshops, industrial establishments.

Field of use of induction motor
1. Used in household chores; Such as - Sewing machine, fan, refrigerator, washing machine, etc.
2. Manage machine tools; Such as - Drill machines.
3. Lathe machines, milling machines, and grinding machines, etc.
4. Punching and hearing machines etc.
5. Crane operation, lift operation, etc.
6. Induction motors are used in mining operations etc.

Advantages of induction motor

1. The structure of the induction motor is very simple and straightforward so it is very strong and durable.
2. Its efficiency is high and it is not required in normal running conditions.
3. Its friction loss is low and the improved power factor works well.
4. It is very easy and simple to start.
5. It does not require any DC exciter.

The difference between induction motor and conduction motor

Induction motor:

Most electric motors receive induced power in the rotor instead of the electric power flowing directly to the rotor.

Such as the way a transformer receives secondary power. This is why this type of motor is called an induction motor.

Conduction motor:

In that electric motor, the electric power is direct to the rotor through the brush and commutator.

That is, the armature that is carried out and converts electrical energy into mechanical energy, such a motor is called a conduction motor.

as result
From the above definition, it is clear that an induction motor is an AC motor that works through transformer action.

Conduction motors are DC motors in which the ball line of the current conductor and the ball line of the magnetic field interact with each other to make the armature rotate strong on one side of the magnetic field and weak on the other.

FAQ in  Induction motor

Q1.Why is an induction motor called a rotating transformer?

Ans: Just as the voltage is applied to the secondary of the transformer without any electrical connection, so is the voltage applied to the rotor of the induction motor. This is why it is called a rotating transformer.

Q2.What is an induction motor?

Ans: An electric motor that converts electrical energy into mechanical energy through an electric power brush and a commutator that circulates directly to the rotor is called a conduction motor.

Q3.Why is an induction motor called a synchronous motor?

Ans: The speed of the induction motor is always slightly lower than the synchronous speed, so it is called a synchronous motor.

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