Answer / kumarabharathi

Soft starters nothing but thyristor control starters,this
different form VFD drives,All VFD drives are soft starters
but All soft starters are not Drives,In VFD we can adjust
the speed,Torque & master-slave operation,But in soft
starters is used only to reduse starting current of motor
And for soft starting of motors.

Answer / karthik

so many soft starters is available in market.fews are abb
siemens,power boss etc.soft startesused to minimise the
starting time of a motor and limit the current also.in
starting time aalso we limit the input voltage of the motor.
Ramp Up
Ramp Down
Pedestal
Step Down
Supply Frequency
Current Limit Time
Current Limit Level
Kick Start Time
Kick Start Level
Arc-less Switching above all parameters also we adjustable n
soft starters.

Answer / hari

1)air cored reactor soft starters(hormonic effect free)
2)Iron core reactor soft starters(hormonic effect will be
there)
2)flux compensating magnetic amplifier starters(FCMA)

Answer / sunil guru

there are various soft starters for both AC and DC machines...
for DC motor>>>>>

1.three point starter
2.four point starter

for AC motor>>>>>

1.star -delta starter.
2.auto transformer starter
3.rotor resistance starter
4.direct on line starter

soft starters are used>>>>>>
to reduce the starting current
to reduce the starting voltage
simultaneously to increase the torque of motor as it gains speed

soft starters are not only used to give a soft start to the motor but also 2 give protections like >>>>>>>>

1.in the absence of the starter the starting current will be too high so it would effect the parallel loads connected and may blow out the fuse

2.if the motor fails to start due to cogging then the circulating current may burn the armature winding of motor

3.as at start the starting current is 10-15 times high so starting torque also 10-15 times high so that torque may damage the motor getting if higher speed than rated.

so the soft starter's are used to start the motor in a safe way

Answer / rvg

Soft starters are used for reducing starting currents of
high capacity motors( above 60 HP ). Ofcourse, these are now
a days used with SCR's.

Answer / rex

one type of starter for three phase squirrel cage motors is
a star delta starter switching the stator windings to star
connection to start ,707 of supply volts across each phase
winding when full speed is reached the stator windings are
then connected in delta connection full supply voltage
across each phase winding.
the inrush current during initial starting is limited with
the reduced voltage thus less current

Answer / thowsif

Delta Primary & Star Secondary &

Delta Primary & Delta Secondary

This two arrangemetns are imposible....

Frequency of rotor emf in induction motor is around A same as stator frequency B 50% C 5 % or below D 30%

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