Divya Shree Nandini presents an overview of induction motors, focusing on the distinction between squirrel cage and slip ring types. Squirrel cage motors are noted for their low cost, minimal maintenance, and higher efficiency but have poor starting torque and speed control limitations, while slip ring motors offer better starting torque and variable speed capabilities at a higher cost. The presentation concludes with a welcoming note encouraging questions and connections on social media.

1. DIVYA SHREE NANDINI
B.Sc (Hons.) Mathematics
Shri Ramswaroop Memorial University

2.  Hi my name is Divya Shree
Nandini.
 Today I hope will be useful for
both you and me.
 Don’t afraid to ask me about
something you’re unsure of.
 You’ll have the opportunity to ask
me questions at the end of the
presentation.
 Enjoy the ride! (she sai  -

3.  “An induction motor is an AC electric motor
in which the electric current in the rotor
needed to produce torque is obtained by
electromagnetic induction from the
magnetic field of the stator winding. An
induction motor can therefore be made
without electrical connections to the rotor.”
 “ It is also calledAsynchronous motor.”

4.  Stator-The Stator is
the stationary part of a
rotary system, found in
electric generators,
electric motors, sirens
or biological rotors.
The main use of a
stator is to keep the
field aligned.

8.  OUTER FRAME- It is the outer body of the
motor.
It protects the inner part of the machine.
 STATOR CORE- Built up of high grade silicon
steel.
Carries the alternating magnetic field.
 STATORWINDING- Stator winding has three
phase winding.

9.  ROTOR-The Rotor is a
moving component of
an electromagnetic
system in the electric
motor, electric
generator, alternator.
Its rotation is due to the
interaction between
the windings and
magnetic fields which
produces a torque
around the rotor’s axis.

10.  SQUIRREL CAGE ROTOR-
The working of an induction
Motor, squirrel cage rotor
which is the most commonly
used one in induction
motors. A phase AC current
passing through a Stator
winding produces a rotating
magnetic field. So as in the
previous case, current will be
induced in the bars of the
squirrel cage.

12.  Squirrel cage induction motors are cheaper in
cost compared to slip ring induction motors.
 Requires less maintenance and rugged
constructions. Because of the absence of slip
rings, brushes maintenance duration and cost
associated with the wear and tear of brushes are
minimized.
 Squirrel cage induction motors requires less
conductor material than slip ring induction
motors, hence copper losses in Squirrel cage
motors are less results in higher efficiency
compared to slip ring induction motors.

13.  Main disadvantage of squirrel cage induction motor is
that they have poor starting torque and high starting
currents.
 Squirrel cage induction motors are more sensitive to
the supply voltage fluctuations.When the supply
voltage is reduced, induction motor draws more
current. During voltage surges, increase in voltage
saturates the magnetic components of the squirrel
cage induction motor.
 Speed control is not possible in squirrel cage induction
motor.This is one of the major disadvantages of
squirrel cage induction motors.

15.  PHASEWOUND ROTOR- It
is also called SLIP RING
ROTOR.A wound-rotor
motor is a type of induction
motor where the rotor
windings are connected
through slip rings to external
resistances. Adjusting the
resistance allows control of
the speed/torque
characteristics of the motor.

17.  High starting torque with low starting current.
Maximum starting can be attained in the slip ring
motor compared to squirrel cage motor by inserting
an external resistance in each phase of the rotor
circuit and cutting the resistance during starting.
 Speeds can be adjusted in the case of slip ring (wound
rotor) motor induction motor by inserting an
resistance. Hence slip ring motors are considered as
variable speed motors.
 Slip ring motors have high over loading capacity,
smooth acceleration under heavy loads, and no
abnormal heating during starting.

18. Initial and maintenance cost is more
compared to squirrel cage motor because
presence of slip rings, brushes, short
circuiting devices etc.
Speed regulation is poor when operated with
external resistances in rotor circuit.
Efficiency and power factor of slip ring motor
is lower compared to squirrel cage induction
motor.

21. The stationary rotor cut the revolving field
and due to electromagnetic induction an
e.m.f. is induced in the rotor conductor.
It becomes a current carrying conductor in
magnetic field and start rotating.
A rotating field is set up in the stator when a
3- phase supply is given.
As the rotor conductor is short circuited
current flows through them.

22. Induction motor rotor always rotate at a
speed less than synchronous speed.
The difference between the flux (Ns) and the
rotor speed (N) is called Slip.
%Slip= (Ns-N) 100
N
Slip speed=Ns-N

23. THANKYOU
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