2. Contents
➢ Introduction
➢ Induction Motor
➢ Principal Parts
➢ Types of Induction Motors
➢ Working Principle
➢ Starting Methods for Induction Motors
➢ Uses of Induction Motors
3. Introduction
The most important inventions of
the modern science is the
Induction Motor. From powering
our homes and offices to driving
industrial machinery, induction
motors have become an integral
part of our lives. But what exactly
is an induction motor, and why is
it so important?
Let's find out,
This Photo by Unknown author is licensed under CC BY-SA.
4. What is an
Induction Motor?
An induction motor is a type of electric motor
that operates on the principle of electromagnetic
induction. It consists of a stator, which is a
stationary component, and a rotor, which rotates
inside the stator. The stator contains a set of
windings that are supplied with alternating
current (AC) electricity. This current produces a
magnetic field that induces a current in the rotor
windings, causing the rotor to rotate.
5. Principal Parts
An induction motor consists of two main parts,
1.The stator
2.The rotor
The stator is the stationary part of the motor, while the
rotor rotates within it. The stator contains the primary
winding, which is connected to an AC power source. The
rotor has a secondary winding, which is induced with a
current by the magnetic field created by the primary
winding. The rotation of the rotor is due to the interaction
between the magnetic fields of the stator and the rotor.
6. Types of
Induction Motors
There are two main types of induction motors,
1.Single-phase
2.Three-phase
Single-phase induction motors are used in small appliances and
machines, such as fans, washing machines, and vacuum
cleaners. They are less efficient than three-phase motors and
have lower power output.
Three-phase induction motors are used in larger machines and
equipment, such as pumps, compressors, and conveyors. They
are more efficient and have higher power output than single-
phase motors.
Single-phase
Three-phase
7. Working Principle
The working principle of an induction motor is
based on the interaction between the magnetic
field of the stator and rotor. When an AC voltage
is applied to the stator winding, a rotating
magnetic field is produced in the air gap between
the stator and rotor. This rotating magnetic field
induces a voltage in the rotor windings, which in
turn produces a current that creates a magnetic
field in the rotor. The interaction between the two
magnetic fields causes the rotor to rotate.
8. The Starting methods for
Induction Motors
The starting methods for single-phase and three-phase induction
motors are different due to the nature of their windings and the
challenges they pose during starting.
Let's take a look at each,
Starting of Single-Phase Induction Motor: Single-phase induction
motors are not self-starting . They require additional mechanisms
to initiate rotation. There are various methods to start a single-
phase induction motor, but the two most common methods are:
1.Split-Phase Induction Motor &
2.Capacitor-Start Induction Motor
9. Starting of Three-Phase
Induction Motors
Starting of Three Phase Induction Motors:
Three-phase induction motors are self-starting due
to the rotating magnetic field produced by the
balanced three-phase supply. There are three main
methods used to start an induction motor,
1.Direct-on-line starting
&
2.Star-Delta starting
10. Starting of Single-Phase
Induction Motors
Split-Phase Induction Motor: This method uses a special winding arrangement with two
windings: the main winding and the auxiliary or starting winding. The starting winding is
equipped with a phase shift relative to the main winding. This phase difference creates a
rotating magnetic field, which allows the motor to start and run in a particular direction.
Capacitor-Start Induction Motor: In this method, a capacitor is connected in series with
the starting winding. The capacitor introduces a phase shift, creating a rotating magnetic
field that enables the motor to start and run in a specific direction. Once the motor reaches
a certain speed, a switch disconnects the starting winding and capacitor from the circuit.
11. Starting of Three-Phase
Induction Motors
Direct-On-Line Starting
Direct-on-line starting is a method used to start
induction motors. It involves connecting the motor
directly to the power source, which causes a surge of
current and torque that can be damaging to the
motor and the connected equipment. However, this
method is simple and cost-effective, making it a
popular choice for many applications.
12. Starting of Three-Phase
Induction Motors
Star-Delta Starting
The star-delta starting method is a common way of
starting induction motors, particularly in
applications where high starting torque is required.
This method involves connecting the motor
windings in a star configuration during starting,
and then switching to a delta configuration once
the motor has reached full speed.
13. Uses of Induction Motors
• Induction motors are widely used in various industrial, commercial,
and residential applications due to their simplicity, reliability, and
cost-effectiveness. Some of the most common uses of induction
motors include
• Industrial Applications: Induction motors are extensively used in
industries for driving various types of machinery and equipment,
such as pumps, fans, compressors, conveyor systems, mixers,
and blowers.
• Commercial Buildings: Induction motors are used in HVAC
(Heating, Ventilation, and Air Conditioning) systems to power air
handling units, chillers, and cooling towers. They are also found
in escalators and elevators for vertical transportation.
14. Uses of Induction Motors
• Residential Applications: In households, induction motors
are present in various appliances like washing machines,
refrigerators, air conditioners, and kitchen exhaust fans.
• Agriculture: Induction motors drive irrigation pumps and
other agricultural machinery used for water supply,
irrigation, and crop processing.
• Automotive Industry: In the automotive sector, induction
motors are used in electric vehicles (EVs) and hybrid
vehicles for propulsion. These are commonly known as
induction or AC motors used in electric cars.
