4000 Amp Bus Failure
4000 Amp Bus Failure
(OP)
Hi All,
Has anyone had any issues with 4000 amp (Spectra) bus Duct failures? The plant I am working at has had two failures in the past year. One failure occurred just outside the mcc rm., and the other occurred just inside the mcc rm. wall. The faults seem to have occurred in the same general location on the bus duct. The issues seems to be with the 3/8" insulated bolt nearest the end of a buss section. I'm am curious, if there were any other incidents with the same issues in the recent past. The Bus Duct is only about two years old, and the Plant E/I engineer has a lot of concern about personal safety. Thanks for any feed back.
Has anyone had any issues with 4000 amp (Spectra) bus Duct failures? The plant I am working at has had two failures in the past year. One failure occurred just outside the mcc rm., and the other occurred just inside the mcc rm. wall. The faults seem to have occurred in the same general location on the bus duct. The issues seems to be with the 3/8" insulated bolt nearest the end of a buss section. I'm am curious, if there were any other incidents with the same issues in the recent past. The Bus Duct is only about two years old, and the Plant E/I engineer has a lot of concern about personal safety. Thanks for any feed back.






RE: 4000 Amp Bus Failure
RE: 4000 Amp Bus Failure
RE: 4000 Amp Bus Failure
Have you contacted the manufacturer?
RE: 4000 Amp Bus Failure
Zogzog: The two buses which failed, were installed in the same manner by two different contractors. The PF maintenance is IR scans at the joints.
Rcwilson: The buses which failed were both installed in a horizontal manner and the support is just out of the pic frame. We thought the support issue may be a cause on the first failure but there were not any signs of twisting of the bus with either failure.
Desertfox: We did contact the manufacturer, they stated since the bus was purchased in 2010 and was not installed for 2 years, and now only being in service for about a year and a half, they would not be liable for warranty. They also said the extent of the arc flash would make it impossible to determine a cause for the failure.
I did see a thread on this site stating, a possible cause may have been the shifting of the bus bars inside the housing due to shipping issues. I do know this bus was shipped in a vertical manner (standing on its side). If the bus bar did shift inside the housing it could have rubbed a wear spot on the insulated pass through bolt. This could have caused the bolt in question to cause a fault to ground. Any thoughts on this??
RE: 4000 Amp Bus Failure
RE: 4000 Amp Bus Failure
I have had a look at the Spectra site and looked at some of the installation manuals (link added) you mention about the 3/8 insulated bolts, I cannot see any sleeve insulated bolts in their instructions assuming of course that I have the correct manual.
http://www.geindustrial.com/publibrary/pubLibResul...
Its the bottom one on this link which mentions blue expoxy.
Can you confirm that the installation was carried out correctly with the manual.
RE: 4000 Amp Bus Failure
The bolt I am referring to is the factory installed bolt nearest the end of the bus section. I will include another pic. Thanks
RE: 4000 Amp Bus Failure
Here are the pics of the two failures, the faults appear very similar in location. Please let me know what you think.
RE: 4000 Amp Bus Failure
RE: 4000 Amp Bus Failure
RE: 4000 Amp Bus Failure
RE: 4000 Amp Bus Failure
I wonder if moisture is getting inside the bus duct and then onto the conductors?
There appears to be rust on some of those pictures which suggest there is condensation around.
Is the bus duct subject to vibration which might loosen the bolts?
I think you need to replace what's damaged and ensure you follow the installation manual to the letter and monitor it very closely, that way if you have no problems then its down to installation, on the other hand if you do have an issue then your looking for a different cause.
RE: 4000 Amp Bus Failure
RE: 4000 Amp Bus Failure
RE: 4000 Amp Bus Failure
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(2B)+(2B)' ?
RE: 4000 Amp Bus Failure
In your post you mention the factory installed insulated bolts, so they are untouched bolts as far as installation goes.
In that case I have to agree with your earlier comments about it not being an installation fault.
This insulated bolt then I presume it passes through the conductors although applies no tension on them.
What exactly does this bolt hold on? I am wondering if this bolt wasn't tightened up correctly at the manufacturer's or works loose in service what the outcome might be.
RE: 4000 Amp Bus Failure
How long was each bus operating before failure ?
We do both megger, hipot (some dc / some ac) and ductor test for acceptance/maintenance various plants. Was any tests ever done ?
RE: 4000 Amp Bus Failure
RE: 4000 Amp Bus Failure
Also the pictures has similar evidence of the fault occurring at the joints. (this may be a weakness in the total system and may bear a close scrutiny at all buss bar joints whether of the straight-thru type of the angular type.
It is possible that the joint cover bolts are too close to the bus bars once installed whether it is the wrong length bolts, shifting of the buss bars inside its housing or exposed bars when the sliding contacts make as in its penetration of male/female joints is not at 100%.
I read in the manual that the insulation system is testet at 5kv hi-pot, this may merit a hipot test of the system at 60-75% of fatory test voltage to see if there are any weakness in the existing system.
Haver a Merry Christmas and a Happy New Year.
RE: 4000 Amp Bus Failure