Answer / roysayan01

From the equivalent circuit of an induction motor it can be
seen that the the expression of current is

I=E/[(jX1+R1)+(jX2+R2/s)

Generally during running condition slip,s=0.03
i.e the value of slip is very low which increases the
resistance (R2/s) in the above eqn and as a result of which
current decreases

but

at starting s=1 and so the resistance (R2/s) is small and
the current is 7 to 8 times higher than the current during
running condition.

Hope i explained it vividly.
For ny doubt or query feel free to mail me at
roysayan01@gmail.com

Answer / esha

The starting current, sometimes called inrush current will be 8-10 times higher than the motor's rated current because the motor is at rest.
When at rest, the motor appears to be a transformer, with it's secondary winding short circuited, i.e. the rotor winding or squirrel cage is a closed circuit. This results in a low impedance to the system voltage and the motor has a "locked rotor" current of typically 6 times full load current, but also up to 8 and sometimes 10 times current.
This starting value is independent of any load attached, however, the inertia of the motor and load has to be overcome. This is especially true when the motor is connected to a load, like a conveyor belt with product on it. The larger the inertia, the longer the motor takes to reach full speed.
As the motor accelerates, part of the starting current power overcomes this inertia and is conveted to kinetic energy.
info from-wikianswer.com

Answer / vinay singh

the air gap path provide more reluctance path to the mutual
flux but mutual flux is constant due to constant applied
voltage. so for constant mutual flux the magnetising m.m.f.
is more and stator draws more magnetising current during
starting.

Answer / sdkarwa

because end rings of the squirell cage induction motor are
shorted

Answer / s.eltarhoni

i confirm that the obove two answers are right and the
second is more detailed but i would like you to answer why
this case appeares only at starting

Answer / richard

during starting time there wont be back emf so it takes 7
to 8 times high current

Answer / stalin raj

The motor needs high torque to starts its rotation.The
torque is directly proportional to the square of the
current.Hence it takes a large current at starting.

Answer / mukhesh

because end rings of the squirell cage induction motor are
shorted so resistance is small it offers that much of
currentt here is no windings but in slip to improve the st
torques windings are present it offers low current than sqirrel

Answer / zakir_vjti20

email me at zakir_vjti20@yahoo.com

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