13.8kV Switchgear

[ZinskI/E]

This may not be directly related to the hazardous area section of the forum, but based on the numerous postings of the experts here, I am hoping for a bit of insight or experience...

At the refinery in which I work, a 13.8kV Westinghouse tie breaker experienced a catastrophic fault (of unknown origin) resulting in significant damage to the busswork, pitting and fouling of the enclosure, and excessive carbon deposits on the insulators, bushings, bussing...basically anything within the affected section of the gear (and even some adjacent). Some parts were correctly deemed un-reusable, others were to be cleaned and returned to service.

Unfortunately, I was assigned cleaning duty. While I understand the utmost importance of cleanliness in MV gear, I am having trouble accepting that denatured alcohol is the only permissible cleaning solution on or near the current carrying components.

I agree that the alcohol should be the final step to remove any conductive films or residues, but can anyone provide reason why any non-corrosive cleaning assortment should/could not be used before the final clean?

Speaking from recent and painful experience, fast evaporating alcohol does not a good cleaner make.

An aside: can anyone recommend a tool or material to clean the many crevices in such a piece of gear while avoiding the surface scarring that leads to tracking?

 

[shepelec]

Boy those failures do make a mess!!

Personally I have found brake parts cleaner to do a nice job. It really cuts through the soot and crap. Scotch Brite or 3M pads do a nice job shining up the bussing and of course, a big bag of rags. Simple green does a good job as well but not as good as the brake cleaner-(same stuff mechanics use on cars.)

 

[zog]

You are better off replacing the insulating barriers to avoid future tracking issues. What was the breaker type?

 

[ZinskI/E]

Thanks for the replies.

Zog - I agree that replacing the barriers is the best answer, but this brought rise to another question: is there any issue with on-site fabrication of the 1/4" bakelite insulating barriers between compartments? This is the route the owner decided to take. Also, it is a Westinghouse draw-out circuit breaker; didn't get any more info than that.

Shep - Brake cleaner is a good thought and I will definitely use it next time around. We did have the Scotch Bright pads on hand but they seemed to scratch the surface of the insulators and the rubber on the dipped buss (albeit shallowly). Do you think this light surface scratching would be a likely source of future failures?

 

[shepelec]

I would only use rags on the insulators and rubber. Scotch Bites are ok for the bare buss. Like Zog said, anything burnt needs to be replaced as it could allow tracking as the carbon is conductive. Megger and high pot everything.

 

[zog]

Zog - I agree that replacing the barriers is the best answer, but this brought rise to another question: is there any issue with on-site fabrication of the 1/4" bakelite insulating barriers between compartments? This is the route the owner decided to take. Also, it is a Westinghouse draw-out circuit breaker; didn't get any more info than that.

That is what I would do, just be sure to get the right material.

 

[SG-1]

I agree that the alcohol should be the final step to remove any conductive films or residues, but can anyone provide reason why any non-corrosive cleaning assortment should/could not be used before the final clean?
QUOTE]

You have to be sure that the cleaner does not chemically react with the material used to insulate the bus bar, the standoff insulators & the bus window insulators between sections.

Stoddards Solvent is an alternative to denatured alcohol. I have never used it, so I do not know about it's effectiveness or even it's current availability.