Three Phase Induction motor working Principle and its Types
Electrical motor converts electrical energy into mechanical energy.
What are the types of motors?
Based on Supply Motor are basically two types: AC and DC Motor. AC motor are divided into two types :Induction motor(Speed is variable), induction motor are also known as asynchronous motor and Synchronous motor(speed is constant ).
What are the types of induction motors?
Depending upon nature of AC supply induction motor are two types (a)Single phase induction motor and (b) 3 Phase Induction motor. Here we will discuss in detail about three phase induction motor.
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General aspects
•The construction of induction motor and induction generator are same.
•Induction motors are popularly used in the industry.
•Main features: cheap and low maintenance.
•Main disadvantages: speed control is not easy.
Overview of Three-Phase Induction Motor
•Induction motors are used in many industrial, residential, commercial and utility applications.
•Induction Motors transform electrical energy into mechanical energy.
•It is used for pump or fan, or connected to some other form such as a conveyor, winder, or mixer.
Application of IM |
3 phase induction motors takes three phase supply from mains and used for various industrial applications because of their following advantages -
1. Three phase Induction motors are very simple and rugged construction.
2. It is are very reliable, robust and having low cost.
3. The efficiency of 3 phase IM is high and its power factor is good at full load.
4. It required minimum maintenance.
4. Three phase induction motor is self starting hence extra mechanism is not required for starting.
They also have some disadvantages-
1. The Speed of induction motor decreases with increase in load, same as a DC shunt motor.
2. If speed is to be varied, the efficiency may change.
Construction
•The three basic parts of induction motor are the rotor, stator, and enclosure.
•The stator is stationary part while rotor is rotating part of induction motor.
•The enclosure protects the stator and rotor of the motor from harmful effects of the environment in which the motor operates.
Bearings which is mounted on the shaft, support the rotor . A fan, also mounted on the shaft, which is used for cooling purpose.
Construction of Induction motor |
Construction of Stator
•The stator winding is wounded on stator core which is made up of several thin laminations.
Coils of insulated wire are inserted into stator slots of the stator core. The stator winding either connected in delta or star configuration. The stator windings of induction motor are connected to the supply mains.
Construction of Rotor
•The rotor is the rotating part of three phase induction motor.
•It can be found in two types:
–Squirrel cage
–Wound rotor
What are the types of 3-phase induction motors?
Three phase Induction motor types : Based on rotor construction three phase Induction motor are two types-
Squirrel cage induction motor:
Rotor winding is composed of rotor copper bars embedded in the rotor slots and their end terminal is shorted end rings arrangements. It is very Simple, low cost, robust and has low maintenance.
Wound rotor or slip ring induction motor:
Rotor winding is wound by wires. The rotor winding terminals can be connected to external resistance through slip rings and brushes for smooth speed control.
•However, the most common type of rotor is the “squirrel cage” rotor.