1- Three Phase Induction or Asynchronous Motor:

Definition: 3 phase induction motor is commonly used in world such like as water pump, air conditioner, blower, production machines, agricultural purpose etc. it is converted electrical energy into mechanical energy so it is connected with moving machines with rubber coupling, pulley drive or belt.

Three phase power supply is applied to stator which is wounded with three phase winding. A rotating magnetic flux is produced on stator winding. This rotating magnetic flux is distributed on rotor by electromagnetic induction effect. An induced emf is produced on rotor after that the rotor is moves.

2- Connection diagram:

3- Working Principle:

Three phase induction motor is also known as asynchronous motor. It is very simple motor. Motor speed is not equal during load or without load. This type motor is called asynchronous motor. In this motor pols and rotor speed are not same. The speed of pols is more in comparison of rotor.

when power supply is applied to the motor then without load motor pole speed and rotor speed are same. After that the load is applied to the motor then rotor speed is decreased. It is the speed of rotor is actual.

          Difference of speed is called slip. We can get this slip by equation. 

          For ex: s = ns-n/ns x 100% 

          where ns = synchronous speed. N = actual speed.
        

4- Advantage of three phase induction motor:

Induction motors are used in world a Loat of industries and domestic. Its more benefits are available for using. Theadvantage points are given below mentioned

1. Three phase motor is self-started motor.
2. Low maintenance in comparison of single phase.
3. construction is very simple.
4. No need of brushes, slip rings and commutator so cost is very low.
5. No fire-hazards because no sparking without slip rings.
6. Efficiency and overload capacity are good.
7. High starting torque.
8. Self-starting no any other support is required.
9. Maintenance cost is reasonable.

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