HT Motor Trips After Stop Command

On what measurement does <...it trip...>, though?

What are the consequences of the <...trip...>?

These snippets, which have been withheld from the forum, are fundamental to the search for the solution(s)!

It's the best that can be done with only two sentences. Not much of a story, is it (rhetorical question - NNTR)?

Sounds like a short in the switch....

https://cr4.globalspec.com/thread/49102/VFD-Behavior-When-Motor-Stops

https://sdvelectrical.blogspot.com/2018/11/dynamic-braking-of-motor.html

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It could be that one phase is opening before the others or two phases are hanging up and causing the motor to be single phased thus causing the trip.

Check your contactor.

Hi

Thanks for ur reply.

It is a ABB vd4 11kv breaker, its not contactor

Thanks

The smallest trip current I can find for this breaker is 630A. I would be nervous using a circuit protection breaker an order of magnitude greater than the anticipated full load. You are not presenting us with a full picture of your situation. Is this breaker that trips also providing power for other loads?

Hope Stop command is not wired in Trip relay circuit!!

Are the rollers nipped when the stop command is issued?

Is there a variable frequency drive between the breaker and the motor?

The motor protective relay that trips the breaker should give you an indication of the type of fault, some code will show up on the display

Your motor circuit must have exceeded the safe parameters of your MV breaker.

Check your motor starting method used as well as the rated amperage of your MV breaker if it is well rated for the job and adjust your parameters where necessary.

You can use a suitable rated "soft starter" to start and stop the motor with a proper stop ramp time setting to achieve a "soft stopping" of the motor and your MV breaker will not trip if well rated. The stop ramp is the time from full voltage until stop voltage (initial voltage) is reached. If you set your stop ramp time to zero, the stop will be like a direct stop, and you will experience the same tripping of the MV breaker.

The thyristors in the soft starter implements the soft start and soft stop of the motor by gradually increasing and reducing the motor voltage according to a set ramp time for the soft starting and soft stopping of the motor.

The stopping method can be changed from "coast to stop" to ramp down stop. The deceleration time must be set properly to avoid the regeneration. The coast to stop or faster deceleration of the motor may cause motor to work as a generator. The motor starts feeding its kinetic energy, converting into electrical, in the capacitor bank of the converter of the VFD. The voltage across the capacitor may reach above the over voltage limit and the drive may trip with over voltage fault.

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