AC hzpt motor electric MOTORS
Working principle
AC motor is a device which converts alternating current right into a mechanical device by using an electromagnetic induction phenomenon. The AC motor includes two basic parts an outside stationary stator having coils supplied with an alternating current to make a rotating magnetic field and an internal rotor mounted on the output shaft making 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. Based on the Faraday’s regulation, this alter in magnetic field induces a power current inside a 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 energy supply is put on the synchronous motor, a revolving field is set up. This field attempts to drag the rotor towards it but because of 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 is the stator winding which comes by a 3-stage supply and the various other one may be the rotor winding which comes by a DC supply. Thus, two magnetic fields are stated in a synchronous motor.
The 3-phase winding produces 3-phase magnetic flux and rotor winding produce continuous flux. The 3-stage finding produces a magnetic field which rotates at a speed called synchronous speed.
When rotor and stator begin rotating, at some time the rotor and stator have the same polarity causing a repulsive force on the rotor and for the next second, they cause an attractive power. But rotor remains in standstill condition due to its high inertial moment. Therefore, the synchronous engine is not self-starting.
Advantages
The motor speed is continuous irrespective of the strain.
Electromagnetic power of the synchronous engine varies linearly with the voltage.
Compared to an induction motor, it operates at higher efficiencies at reduced speeds
Disadvantages
It isn’t self-starting. It needs some arrangement for starting and synchronizing.
Since its starting torque is zero, it cannot be started while 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 is also named as Asynchronous not since it always runs at a speed less than the synchronous speed. The induction electric motor can be classified into mainly two sub-groups. The single-phase induction motor and the 3-stage induction motor.
In an induction electric motor, the single armature winding acts both as an armature winding in addition to a field winding. The flux is definitely produced in the air gap whenever the stator winding is supplied to the Atmosphere Gap. This flux will rotate at a fixed 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 in an induction motor, an alternating flux will be produced. This flux rotates at an asynchronous velocity and this flux is called the rotating magnetic field. Because of the relative speed between the stator RMF and rotor conductor, an induced EMF is definitely created in the rotor conductor. A rotor current is usually then produced because of this induced EMF.
This induced current lags behind the stator flux.
The direction of the induced current is in such a way that it will oppose the source of its production. The foundation of the production is the relative velocity between rotor stator flux and rotor. The rotor will try to rotate in the same direction as a stator to be able to reduce the relative velocity.
The speed of rotating magnetic field is distributed by
DC motor
Single phase induction Motor
AC electric motor which utilizes solitary phase power supply is named single phase induction engine.it is commonly found in the domestic and industrial application.it includes stator and Rotor component. A single-phase power is given to the stator winding. A squirrel cage rotor laminated with the iron core is linked to a mechanical load with the aid of 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 engine is mounted on the mechanical load by making use of the shaft. Because of the rotating flux in the stator, an alternating electromagnetic field is usually induced in the rotor. But this alternating flux did not provide required rotation to the rotor. That is why the solitary phase motors are not self-starting.
In order to achieve self-starting convert this solitary phase motor into a two-phase 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
Refrigerator
Pumps
Compressor
Portable drills
Three Phase Induction Motor
When a three-phase supply is connected to the stator winding, this kind of motor is called three-phase induction motor. As being a single phase electric motor, it has also both stator and rotor winding. The stator wounded by a 3-phase winding given by a 3-phase supply produces an alternating flux which rotates at a synchronous rate.
Working principle
When AC supply is directed at the 3-phase winding of the stator, it generates an alternating flux which revolves with synchronous rate. This rotating magnetic field induced an EMF in the rotor which in turn produced an induced current which flows in a path which opposing that of the rotating magnetic field, produce a torque in the rotor. The acceleration of the rotor will never be identical to that of the stator. If speed matches no torque will produce
Advantages
Simple and rugged construction
High efficiency and great power factor
Minimum maintenance
Self-starting motor.
Disadvantages
Speed decreases with increase in load
Speed control is difficult
Having poor starting torque and high rush current.
Application
Large capacity exhaust fans
Driving lathe machines
Crushers