Ac electric motor

AC ELECTRIC MOTORS

Working principle
AC motor can be a device which converts alternating electric current right into a mechanical device through the use of an electromagnetic induction phenomenon. The AC motor contains two basic parts an outside stationary stator having coils given an alternating current to make a rotating magnetic field and an inside rotor mounted on the output shaft creating another rotating magnetic field.

The rotor can be an electric conductor which is suspended in the magnetic field. Because the rotor is constantly rotating there exists a modify in magnetic field. According to the Faraday’s regulation, this alter in magnetic field induces an electric current in the rotor.

Types of AC Electrical Motor
The AC motors can be basically classified into two categories, synchronous, and asynchronous motors
Synchronous Motor
These motors operate at a synchronous swiftness and convert AC electrical energy into the mechanical power.
When the power supply is put on the synchronous motor, a revolving field is set up. This field attempts to drag the rotor towards it but due to the inertia of the rotor, it cannot perform it. So, you will see no starting torque. Because of this, the synchronous motor is not a self-starting motor.

Principles of operation

This motor has two electrical inputs. One may be the stator winding which comes by a 3-stage supply and the other one may be the rotor winding which is supplied by a DC supply. Thus, two magnetic areas are produced in a synchronous motor.

The 3-phase winding produces 3-phase magnetic flux and rotor winding produce constant flux. The 3-phase finding generates a magnetic field which rotates at a swiftness called synchronous speed.

When rotor and stator start rotating, at some point the rotor and stator have the same polarity causing a repulsive force on the rotor and for another second, they trigger an attractive pressure. But rotor remains in standstill condition because of its high inertial moment. Therefore, the synchronous engine is not self-starting.

Advantages

The motor speed is continuous irrespective of the load.
Electromagnetic power of the synchronous motor varies linearly with the voltage.
In comparison to an induction motor, this operates in higher efficiencies at lower speeds
Disadvantages

It isn’t self-starting. It requires some arrangement for starting and synchronizing.
Since its starting torque is zero, it can’t be started whilst having a load
It cannot be used for applications which require frequent beginning so when self-starting is required.
Application

Dampers
Conveyor systems
Variable transformers
Cryogenic pumps
Induction Motor
The induction motor can be named as Asynchronous not because it always runs at a speed less than the synchronous speed. The induction engine can be classified into mainly two sub-types. The single-phase induction motor and the 3-phase induction motor.

In an induction electric motor, the single armature winding acts both as an armature winding as well as a field winding. The flux is usually produced in the air gap whenever the stator winding is supplied to the Surroundings Gap. This flux will rotate at a set speed. Therefore, it will induce a voltage in the stator and the rotor winding.
The current flow through the rotor winding reacts with the rotating flux and produces the torque.

Basic Working Principle

When an AC supply is fed to the stator winding within an induction motor, an alternating flux will be produced. This flux rotates at an asynchronous acceleration and this flux is known as the rotating magnetic field. Because of the relative speed between the stator RMF and rotor conductor, an induced EMF is usually developed in the rotor conductor. A rotor current is certainly then produced for this reason induced EMF.

This induced current lags behind the stator flux.

The direction of the induced current is in such a way that it tends to oppose the foundation of its production. The source of the production is the relative velocity between rotor stator flux and rotor. The rotor will attempt to rotate in the same path as a stator to be able to reduce the relative velocity.

The speed of rotating magnetic field is given by

DC motor

Single phase induction Motor
AC electric engine which utilizes solitary phase power supply is named single phase induction motor.it is commonly found in the domestic and commercial application.it consists of stator and Rotor part. A single-phase power is directed at the stator winding. A squirrel cage rotor laminated with the iron primary is connected to a mechanical load by using the shaft.
Principle of operation

When the single-phase supply is given to the stator winding an alternating flux will produce in the stator winding.

A squirrel cage motor is attached to the mechanical load with the help of the shaft. Because of the rotating flux in the stator, an alternating electromagnetic field is induced in the rotor. But this alternating flux didn’t provide required rotation to the rotor. This is why the single phase motors are not self-starting.

In order to achieve self-starting convert this solitary phase motor into a two-phase electric motor for temporarily. This is often achieved by introducing a starting winding

Advantages

Lightweight
Efficient transmission
Fewer substations required
Disadvantages

Cannot handle the overload
No uniform Torque
High insulation cost
Application

hzpt motor Refrigerator
Pumps
Compressor
Portable drills
Three Phase Induction Motor
When a three-phase supply is linked to the stator winding, this type of motor is called three-phase induction motor. Just like a single phase electric motor, it has also both stator and rotor winding. The stator wounded by a 3-phase winding supplied by a 3-stage supply generates an alternating flux which rotates at a synchronous swiftness.
Working principle

When AC supply is given to the 3-phase winding of the stator, it produces an alternating flux which revolves with synchronous quickness. This rotating magnetic field induced an EMF in the rotor which in turn produced an induced current which flows in a direction which reverse that of the rotating magnetic field, produce a torque in the rotor. The velocity of the rotor will not be identical to that of the stator. If rate fits no torque will produce

Advantages

Simple and rugged construction
High efficiency and good power factor
Minimum maintenance
Self-starting motor.
Disadvantages

Speed decreases with upsurge in load
Speed control is difficult
Having poor beginning torque and high hurry current.
Application

Large capacity exhaust fans
Driving lathe machines
Crushers

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