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Why Soft Starter stopping current taking high?

Dear All,


After analysis I found soft stater stoping current higher than its starting current.


As per rated current of motor 721A but starting current taking 2300A and stoping current also taking 2400A.


Please advise what is the reason/
  • Deaccelerating the kinetic load.
  • It is quite normal and nothing to be concerned about. The drive may allow you to reduce the breaking load but it will just take longer to stop the drive. I suspect it is either a large load or a centrifugal machine that has high inertia
  • If anyone expert on Soft Starter, Please review and make your valuable comments.
  • What load is it driving - static and running motor impedance, and spin-up time, and permitted starts per hour will define what the inrush will be, and how long it will last.

    The drive reflects this - does  the application allow the motor to be started more  slowly ? if so you can lower the peak in-rush at the expense of it lasting longer.

    Decide what  current and spin up times you can tolerate and see if that is within the range that is possible for that motor.


    For example in the file you link,  what have you put in for registers 4026 and 4039  350% of 720A amps is about 2.2kA, so it is probably just about limiting if you lower 4039 a bit, the peak current will reduce.


    But, does the motor really come up to full speed in 10 seconds - that is quite fast for a motor of a few hundred horse power. You may need to lengthen time  or accept the high current.

    As regards stopping, the energy of the spinning load has to go somewhere - are you returning this energy to the supply (regenerative brake) or is there a big resistor getting hot somewhere ?

    What is in registers 4029 and  4044, and right now how long is it taking to spin down.?


    This may get you started. Do not make dramatic changes to the register settings without checking that it has the expected effect for a small change in the value, in case some other setting is competing.