what are thr single phase and three phase induction motor .how it works &what r its applications.?

Answer 1

How they work:

The difference between single/three phase induction motors is primarily in the stator windings. For a three phase induction motor, there are wire windings distributed outside of the motor shaft (rotor) such that when the three phase AC electricity is applied a constant rotating magnetic field is induced inside. The same principle more or less applies to a single phase motor, but in single phase windings the magnetic field is stationary and pulsates (more complicated operation).

On the rotor, there are usually "cage bars" oriented in a cylinder surrounding the rotor (some designs use a wire winding). In any case, the point of the rotor in an induction motor is that the stator magnetic field induces a voltage on the bars/windings of the rotor (kind of like how a transformer works). Current flows through the rotor bars and in turn creates a rotor magnetic field. The rotor magnetic field tries to stay aligned with the rotating stator magnetic field (and so the motor shaft rotates).

The induced voltage in the rotor only occurs when the rotor is turning at a different speed than the stator magnetic field. So, when a load torque is applied to the motor under normal conditions, the rotor slows down but a voltage is induced in the rotor (and thus a magnetic field) that "helps" the rotor keep up. This is the major difference of operation as compared to a synchronous motor (where speed is constant under loading). That's my summary of what I have learned from the sources below. The Wikipedia article is pretty good (could use an improvement here or there). Try to find a site that shows a picture of the inside of the induction motor; it will help explain what I am talking about as far as the stator/rotor construction.

What applications:
Pretty much anywhere you need a clean/convenient means of rotating machinery. Appliances, industrial applications, etc.

Answer 2

It can be shown mathematically that "The total instantaneous power for a balanced 3-phase system is constant and is equal to 3 times the average power per phase.” That means that the rotating stator and rotor magnetic fields in a three phase motor are not pulsating at all as they are in a single phase motor. Edit 1 I would agree that size, fan etc. probably have more to do with the differences in sound than 1ph vs 3ph, but I suspect this is an academic question that should have been preceded by "all other things being equal."

Answer 3

single phase motor has just one coil of excitation or one stator, 3 phase has 3 coils in star or delta configuration. All induction motors work on same principle, the electric field induced in rotor reacts with electric field in stator, driving the motor. Single phqse motor usedin household appliances, while 3 phase used in industry.

Answer 4

Wikipedia has an excellent article under "electric motors" that has sections on poly-phase and single phase induction motors that explains what is, how it works, and applications.

Answer 5

Go for B L Thareja vol2&3 .Its an excellent book for all types motors

Answer 6

one phase and one neutral means -- single phase motor and thre e pahse -- means thre phases motor.
It si just common . Thre are many a things to learn about.

Answer 7

Single phase power system is widely used as compared to three phase system for domestic purpose, commercial purpose and to some extent in industrial purpose. As the single phase system is more economical and the power requirement in most of the houses, shops, offices are small, which can be easily met by single phase system. The single phase motors are simple in construction, cheap in cost, reliable and easy to repair and maintain. Due to all these advantages the single phase motor finds its application in vacuum cleaner, fans, washing machine, centrifugal pump, blowers, washing machine, small toys etc.

The single phase ac motors are further classified as:

1.Single phase induction motors or asynchronous motors.

2.Single phase synchronous motors.

3.Commutator motors.

Working Principle of Single Phase Induction Motor :

NOTE: We know that for the working of any electrical motor whether its ac or dc motor, we require two fluxes as, the interaction of these two fluxes produced the required torque, which is desired parameter for any motor to rotate.
When single phase ac supply is given to the stator winding of single phase induction motor, the alternating current starts flowing through the stator or main winding. This alternating current produces an alternating flux called main flux. This main flux also links with the rotor conductors and hence cut the rotor conductors. According to the Faraday’s law of electromagnetic induction, emf gets induced in the rotor. As the rotor circuit is closed one so, the current starts flowing in the rotor. This current is called the rotor current. This rotor current produces its own flux called rotor flux. Since this flux is produced due to induction principle so, the motor working on this principle got its name as induction motor. Now there are two fluxes one is main flux and another is called rotor flux. These two fluxes produce the desired torque which is required by the motor to rotate.

An electrical motor is such an electromechanical device which converts electrical energy into a mechanical energy. In case of three phase AC operation, most widely used motor is Three phase induction motor as this type of motor does not require any starting device or we can say they are self starting induction motor.

Working of Three Phase Induction Motor :

Production of Rotating Magnetic Field

The stator of the motor consists of overlapping winding offset by an electrical angle of 120°. When the primary winding or the stator is connected to a 3 phase AC source, it establishes a rotating magnetic field which rotates at the synchronous speed.
Secrets behind the rotation:
According to Faraday’s law an emf induced in any circuit is due to the rate of change of magnetic flux linkage through the circuit. As the rotor winding in an induction motor are either closed through an external resistance or directly shorted by end ring, and cut the stator rotating magnetic field, an emf is induced in the rotor copper bar and due to this emf a current flows through the rotor conductor.
Here the relative speed between the rotating flux and static rotor conductor is the cause of current generation; hence as per Lenz's law the rotor will rotate in the same direction to reduce the cause i.e. the relative velocity.
Thus from the working principle of three phase induction motor it may observed that the rotor speed should not reach the synchronous speed produced by the stator. If the speeds equals, there would be no such relative speed, so no emf induced in the rotor, & no current would be flowing, and therefore no torque would be generated. Consequently the rotor can not reach the synchronous speed. 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.

Thus the three phase induction motor is:
• Self-starting.
• Less armature reaction and brush sparking because of the absence of commutators and brushes that may cause sparks.
• Robust in construction.
• Economical.
• Easier to maintain.

Application of Single Phase Induction Motor :

It is not a matter of kilo watts or size but it is a matter of motor design. Most of the single phase motors create phase difference in the windings by using a capacitor. Others use a shaded pole and don't need a capacitor.

Some motors have internal centrifugal switch which acts as a motor starter. So single phase motors, in majority of the cases, don't need external starter like 3 phase motors need.

Application of Three Phase Induction Motor :

1.Used in Robotics.
2.Used in Billet Shearing Machines, Section Straightening Machines in Rolling mills.
3.Used in the Grinding machine.
4.Used in varying load machine.
5.Printing machine
6.Lathe machine
7.Drives of fan.

For more info visit :

https://www.electrikals.com/

Answer 8

What in the world are you talking about man.