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Topic Title: Use of VCB for motor
Topic Summary: CAn VCB be used for HT motor
Created On: 15 March 2012 11:39 AM
Status: Read Only
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 15 March 2012 11:39 AM
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Posts: 1
Joined: 18 July 2011

Two motors of 2000kW & 1750kW failed in site due to insulation failure which was attributed to voltage surges apart from heating. MCOV of serge arrestors is in line with the requirement and rated surge protection level 2.2PU. Failure of this 2 motor occurred during switching OFF operation. With the detail study on available resources, it was formulate that switching of motors with VCB causes surge over voltage. The Pre & reistiking lead to flowing of arc current,which is an unwanted phinomenon in VCB. Use of choke do not garantee in protecting the motor.

The solution is use of magnetic rings with special non-linear properties that are sensitive to higher freq, which are placed around the conductors connecting the VCB and the motor, and positioned even at the VCB end. In such an application the choke may be use dindependently by means of snubber and surge arresters. IS THIS A CORRECT SOLUTION? or STILL THE VCB MANUFACTURED IN THE WORLD HAS THIS ISSUE?
 19 March 2012 12:47 PM
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Posts: 187
Joined: 25 February 2008

It's not clear from your description what your point is.
I'm guessing VCB is voltage circuit breaker.
If so is your point relating to arcing on the breaker opening should be a design issue known by the manufacturer.

Have you contacted them directly.
What is the supply voltage to the 2 motors.

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