Three Phase Induction Motor Principle:
Induction motors are worldwide used for many commercial, industrial, residential and utility applications.In three phase Induction Motor, there are three single phase lines with the phase difference of 120°.
The same phase difference is available in the rotating magnetic field that helps to move the rotor. If we have three phases like A, B and C, when phase A is magnetized, then the rotor is moving towards the A Phase. In the second step B phase will get magnetized and attract the rotor and then the same process in done with phase C. So the rotor will continue to rotate.
It transforms the electrical energy into mechanical energy. These motors can be a part of a pump or fan, and also can be connected with some other form of mechanical equipments like a mixer, conveyor or winder.
Three Phase Induction Motors are used in:
- Varying load machine. Printing machine Lathe machine Drives of fan.
- The Grinding machine and Robotics.
- Billet Shearing Machines, Section Straightening Machines in Rolling mills.
Advantages:
The main advantages of 3 Phase Induction Motors are:- Very simple and rugged construction
- Reliable with having low cost
- Minimum maintenance required
- High starting torque and the smooth rotating magnetic field
- Have the high efficiency and good power factor
- Available in a range of sizes from a fraction
- 3 phase induction motor is self-starting
Disadvantages:
These motors have some drawbacks which are:- When motors are operated below its full load capacity, it can cause of low system power factor.
- Speed decreases with increase in load, just like a DC shunt motor
- It is almost a constant speed motor.
- If speed is to be varied, we have sacrificed some of its efficiency
- High starting current.
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