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Is cable that has experienced a fault still good?

Is cable that has experienced a fault still good?

Is cable that has experienced a fault still good?

(OP)
We have a 5000 HP motor that operates at 13.8kV and is low resistance grounded.  

The motor was recently rewound. The motor shop replaced the internal cable leads between the motor windings and the peckerhead. These new internal cables were run so that one of them touched one of the internal condensate heaters. This caused a ground fault.

The motor shop electricians came out after hearing of the mishap.  They opened up the motor, repaired the internal cable with something much like a splice kit, re-routed it, meggered the cable, which it passed... and called it good.

The plant is not happy with the solution and is claiming these leads should be replaced in total.  Apparently this request is a big expensive job. Thus the dispute and the question.

One other note: upon inspecting this internal cable it was found that these flexible leads are 800 strand. 5 of the strands were broken off.

Can a cable that has faulted like this possibly be bad?
Is there a code article, industry best practice or anything that either side can point to and say they are right?


 

RE: Is cable that has experienced a fault still good?

BDN--

From what you described, the repair will work.  If I were in a hurry to get a motor back on line, I would consider this sort of thing, assuming that my motor (or the work thereon) was not under warranty.

However, if **I** were the client and the problem was a direct result of a mistake by the motor shop, AND I had time to do it, I would want the lead replaced.  I paid for new, I should get NEW, not repaired.

Five strands out of 800 is no big deal.

old field guy

RE: Is cable that has experienced a fault still good?

Perhaps one alternative would be:

Your plant is concerned about the viability of the cable.  The motor shop sez the cable repair is fine.(and probably is)

Get the motor company to guarantee the cable repair for some extended period of time. Maybe 2X the motor rewind guarantee, or three years or ?.

If it runs for three weeks it's probably going to be fine forever.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Is cable that has experienced a fault still good?

Or request a Tan Delta or Partial Discharge assessment of the cable.  

RE: Is cable that has experienced a fault still good?

I assume thoroughly inspected the remaining cables for proper routing?

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