Answer / s.raghavendra

Basically to rotate an induction motor there should be some phase difference for the input excitation.For a three phase supply there is a phase shift of 120 degrees for each phase but in case of single phase there is no phase shifting . In order to produce a phase shift in single phase a capacitor is placed because a capacitor leads the current by some phase angle from voltage supplied which is the inherent property of a capacitor to charge and discharge itself , helps in creating a phase difference in single phase supply which starts the motor

Answer / durai

To produce a rotating magnetic field we need at least two
phases.with single phase u cannot produce rotation.

So at the time of starting capacitor(starting winding) used
as a second phase to produce field

After that fan will rotate with main winding only

Answer / nilkanth tailor

ABOVE MEENAKSHI ANSWER IS RIGHT...BUT IN JUST SINGLE
LINE...CAPACITOR IS USED FOR PHASE SHIFT...COZ THIER IS
SINGLE PHASE SO NO ANY PHAE DIFF...TO REVOLE MOTOR PHASE
DIFF IS NECESSARY...SO IN STRARTING CAPACITOR NEEDS TO
CHAGE IN PHASE SHIFT...

Answer / meenakshi

there vil b two windings. they are main winding n starter
winding of two different inductances.i.e, one with low
inductance n another with higher value. so ther vil be a
phase shift of q1 and q2(say some angle)in accordance with
inductance value. NOW, IN ORDER TO INCREASE THE PHASE
DIFFERENCE BETWEEN Q1 N Q2, WE EMPLOY A CAPACITOR OER
HERE,WHICH MAINLY HELPS IN STARTING.

Answer / manoj kumar

We use Capacitor in Single Phase Induction Motor
to produce the starting tourque.

Answer / waseem khan

in single phase induction motor magnetic field is not rotating
(but pulsating i.e. increases in one direction and then in
other direction sinusoidally),so to make it rotating the
single phase winding is split into two(auxiliary and main)
AUXILIARY---it has high resistance and low inductance as
compared to main winding hence current in this winding lags
the voltage by a small angle whereas the current in the main
winding lags voltage by large angle .hence in this way we
get a phase difference between these two currents .this is
enough to make the motor self starting but if we add
capacitor to the auxiliary winding current in this winding
leads to the voltage and hence a greater phase difference is
obtained between the two currents and a rotating field is
obtained and power factor is also increased....
IF WE INDUCTOR IN PLACE OF CAPACITOR THEN THE TWO WINDINGS
WILL BECOME SIMILAR THEREBY LOWERING THE PHASE ANGLE BETWEEN
THEM AND POWER FACTOR OF SUPPLY IS ALSO REDUCED TO A VERY
LOW VALUE

Answer / sms

Dear Friends, We can say, in order to generate the
sufficient starting torque we have to split the phase in to
two & That is the purpose of capacitor.

Answer / karuna nidhan singh

we use capacitor in single phase induction motor because
here is only single phase so no any phase difference.To
revolve the motor we want phase difference (shift) is
necessary. so we use capacitor in single phase induction motor.
In order to generate sufficient rotating torque we have
split the phase in to two and so we can use it.

Answer / vishnu sharma

as above answer why capacitor is uses ? friends ,1-phase i.m
is not self starting so we use two windings to produce
rotating torque by adding one winding ,due to inductive
nature the current will more lagging the voltage so power
factor is decreases to increase power factor we use only
capacitor is used here

Answer / abhay

Friends i know single winding can not generate rotating
field ,but why only capacitor used for starting why
inductor or other are not used?

Difference between field rheostat and armature rheostat.

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