In this slide given description about different Type of Single phase induction Motor. i.e.Capacitor start motor Permanent capacitor motor Capacitor start capacitor run motor

1. Name :- Smit Shah -140410109096
Rawat Suraj-140410109085
S.Y electrical 2 Sem 4
Subject:-AC Machines
Topic :- Type of Single phase induction
Motor…..

2. INTRODUCTION
 The single-phase induction machine is the most
frequently used motor for refrigerators, washing machines,
clocks, drills, compressors, pumps, and so forth.
 The single-phase motor stator has a laminated iron core
with two windings arranged perpendicularly. One is the
main and the other is the auxiliary winding or starting
winding.

3. Operating principle
 The single-phase induction motor operation can be
described by two methods:
– Double revolving field theory; and
– Cross-field theory.
 Double revolving theory is perhaps the easier of the two
explanations to understand so we will discuss the double
revolving theory only.

4. Double revolving field theory
 A single-phase ac current supplies the main winding that
produces a pulsating magnetic field.
 Mathematically, the pulsating field could be divided into
two fields, which are rotating in opposite directions.
 The interaction between the fields and the current induced
in the rotor bars generates opposing torque.

5. Resultant flux φr = 2 x
φ 𝑚
2
cos
2Ɵ
2
= φ 𝑚cos Ɵ
5

6. 6

7. Starting torque
 The single-phase motor starting torque is zero of the
pulsating single-phase magnetic flux.
 The starting of the motor requires the generation of a
rotating magnetic flux similar to the rotating flux in a
three-phase motor.
 Two perpendicular coils that have currents 90° outof-phase
can generate the necessary rotating magnetic fields which
start the motor.
 Therefore, single-phase motors are built with two
perpendicular windings.

8.  The phase shift is achieved by connecting
– a resistance,
– an inductance, or
– a capacitance in series with the starting winding.
 Most frequently used is a capacitor to generate the starting
torque.

9.  Single-phase induction motors are classified and named
according to the method employed to make them self-starting.
(1) Split-phase induction motor : ( started by two phase motor
action through the use of an auxiliary or starting winding)
(2) Capacitor motors : ( started by two phase motor action
through the use of an auxiliary and a capacitor)
(i) Capacitor-start induction run motor
(ii) Capacitor run induction motor
(iii) Capacitor-start and Capacitor run induction motor
(3) Shaded-pole induction motor :(started by the motion of the
magnetic field produced by means of shading coil around
A portion of the pole structure)

10. Split phase induction motor
10
Two winding
Main winding &
auxiliary winding
90 degree phase
angle
Main winding –
low resistance and
high reactance
Aux winding- high
resistance and low
reactance
Switch = motor
pickup its 75 % of
its rated speed.

11. Working
11
Is lags by V because low reactance
and high resistance
Im lags V by very large angle due to
high reactance
Starting torque proportional to sin α
Disconnect switch after reach its 75
% of rated speed

12. Centrifugal switch- operation
 It is connected in series with the auxiliary winding and
mounted on the rotor shaft. When the motor started and
reaches 75% of synchronous speed, CFS is mechanically
opened and in running condition auxiliary winding
remains cutout from the circuit.
 Therefore, the motor runs only with main winding.

13. Characteristics
1.Starting torque – 1.5 times to 2 times the full load torque.
2. Starting current – 6 to 8 times the full load current.
3. Operating power factor – 0.55 to .65.
4. Efficiency – 60-65%
5.Power rating-(1/20 to 1/2kW)
6. Speed range- 2875 rpm to 700 rpm

14. Applications
 It has low starting current and moderate starting torque. It
is used for easily started loads and typical applications
include fans, saws, washing machines, grinders, blowers
centrifugal pumps, oil burners, domestic refrigerators etc.

15. Capacitor induction motor
1. Capacitor start motor
2. Permanent capacitor motor
3. Capacitor start capacitor run motor
15

16. Capacitor start motor
16
Electrolytic capacitor
90degree phase angle
Im and Is
Im lags V due to high
reactance of main
winding
Due to capacitor Is lead
V
Im and Is angle 90
High starting torque
Apps: Lathes, drilling
machiine,fan etc

17. Characteristics
1.Starting torque- 3.5 to 4.5 times the
full load torque
2. α-varies from 30˚ to 80˚-Starting
torque can be improved
3. Power factor varies from 0.65 to 0.75
4. Efficiency– 65 to 70%
5. Power rating –1/10 to 3/4 kW

18. Requirements of capacitor
 Electrolytic capacitors are used as starting capacitors ,value
around 50μF to a few hundred micro-farads.
 Capacitor designed for extremely short time duty service
and is guaranteed for not more than 20 periods of
operation/hr, each period not to exceed 3 seconds.

19. Applications
 This motor has high starting torque and therefore is used
for hard start loads such as pumps, compressors,
refrigeration units, conveyors, certain machine tools etc.

20. Capacitor start, capacitor run motor
20

21. Characteristics
1.Starting torque – 3 to 3.5 times the full load torque.
2. Efficiency – 60% approx.
3. Power factor-0.9 approx.
4. Power rating- 1/8 to 3/4 HP
5. Pull out torque- up to 260% of
rated torque

22. Applications
 It combines the advantages of capacitor start and
permanent-capacitors and is used for hard to start loads
such as compressors, refrigerators, pumps, conveyors etc.
 These motors are often employed requiring a quite
operating motor such as in hospitals, studios.

23. Shaded-pole induction motor

24. Theory of operation
 Small motors requiring only small starting torque may be
made self-starting by using low resistance copper bands
called shading bands.
 The emf induced in the shading band causes a current to
flow in the band. This current opposes the change of flux
to which it is due and thus there is a time lag between the
fluxes in the shaded and unshaded portion of the pole.
 The flux in the shaded portion of the pole lags the flux in
the other portion. The results is like a rotating field moving
in the direction from the unshaded to the shaded portion
of the pole and a starting torque is produced.

25. Characteristics
1.Low starting torque – 0.4 to 0.8 times the full load torque.
2. Efficiency-35% approx.
3. Powerfactor-0.45 approx.
4. Pull out torque- 15% of full load torque.
5.Power rating-1/300 to 1/20 HP (2.5W to
40W)

26. Applications
 Because of their poor starting torque, low power factor and
poor efficiency such motors are only suitable for low power
applications such as for toys, portable fans , electric clocks,
hair dryers, slide projectors, humidifiers, small business
machines such as photo copying machines, vending
machines, advertising displays etc.