Answer / ganesan_002000

Softstarter can control the motor only at the starting
time, during running time it will be by-passed! but VFD's
can be used both to start as well as to control the speed
of the motor while its running!!

Answer / senindra123

soft starters is using for smooth starting only which will
be by paseed while running.

variable frequency drives are using for smooth atarting and
running. while running we can control the speed of the
motor also.

Answer / kk_london

in soft starter you cannot control the speed of motor where
as in vfd drives speed can be varied by giving digital
inputs to the drive via plc. But both can control the
starting torque of the load.

Answer / satyanarayana gupta

the main function of variable frequency drive is to
control speed of the motor according to the load it just
works as control system with feedback according to that
feed back it will change its speed

where as soft starter it will
just monitor the speed at starting time only



by using vfd's most of power consumtion is reduced

Answer / muhammad ashraf

Softstarter can control the motor only at the starting
time, during running time it will be by-passed! but VFD's
can be used both to start as well as to control the speed
of the motor while its running. and also VFD is control the
current of the motor.

Answer / pardeep.kumar/hoshair pur/

Dear All,
VFD variable frequency drive means it will operate as per
our selected accelration de accelationa nd torque boost.

And Soft starter is device which will limit our starting
torque also.
Its majour application is in textile,A motor of 50 hp
connected to 150 spindles in which thread is unwinding from
samll cone to big cone,if it will start by a normal vfd or
direct start then due to large torque in starting as per
induction motor charecterstics,all thread will get broken.
But due to Softstarter it will limit the starting torque.
Soft starter limits the torque by limiting its current and
voltage. thats all.

what is the calculation formula for motor starting torque,running torque, running torque.

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