Refurbish and Re-use Busbar? 3

[JD0the0EE]

I am working on a project to replace a motor control center that burned down. The client wants me to look into re-using the busbars feeding the MCC. The feeder busbars come from a sub-distribution panel nearby and enter through the top of the MCC. It doesn't look like the bars were above the main part of the fire, but I'm sure they got fairly hot. I haven't been able to locate information regarding when or how busbars can be refurbished. Anyone have experience with this?

 

[dpc]

If this is the non-segregated sandwich style 480 V bus, I'd replace it. The heat may have damaged the insulation between the phases. If it is air insulated, it might be OK to re-use.



David Castor

http://www.cvoes.com

 

[Zogzog]

Here you go, have fun

http://www.pearl1.org/standards/Low...d - Low Voltage Motor Control Center Rev5.pdf

 

[JD0the0EE]

Thanks for the information. Just for grins, here's some pictures of what I'm dealing with. The site cleaned out the equipment before we arrived, so this is what we saw. Looks like the fire started in Section 5 (from the left). The bus enters at the top of Section 2. I have been told it's nothing a little emery cloth and elbow grease won't fix. In my mind, the sections dropping down to connect the MCC are out at a minimum.

 

[EEJaime]

Hello,

Maybe it's just me, but I wouldn't put my name to anything using equipment coming out of that mess! What are you really going to save? Is the increased labor, effort, doubt and exposure worth a few bucks? Not in my book. If the Owner is directing you in writing to do so? That is one thing. If he is asking you to evaluate it and do so if you think it's ok? Not a chance in Hades.

And BTW, a courtroom defense that stipulates : "But all these expert yahoos on the internet said it was ok!" Doesn't wash well.

JMO,

Good luck,
EEJaime

 

[Zogzog]

I am with Jamie, nto only are you taking a big risk repairing that but in the end it will likely cost more than replacing. I have sections you can use to replace the damaged sections and buckets, or replace it all with new.

 

[Zogzog]

New may be a 8-10 week lead time, but I just checked with my MCC guy and he says we have some of those sections we could ship ina few days if you want to provide specs.

 

[dpc]

I don't think I'd waste much time trying to salvage anything associated with this, unless it's one of a kind. There will be products of combustion covering everything, include surfaces that can never be reached for cleaning.

480 V MCC gear is pretty close to junk even when new - it will be cheaper to buy new junk than to try to repair burned up junk.



David Castor

http://www.cvoes.com

 

[JD0the0EE]

Just to clarify, I am not being asked if the panel can be refurbished. I agree that is an obvious no. Also, I didn't mean to give the impression that I wanted advice from "the internet yahoos" to use professionally. All I'm looking at is whether the incoming bus could be refurbished. I am no more concerned about cost than you when it comes to safety or sound engineering. However, if there is a method of refurbishing the bus that works as well as the original and costs less than replacing it, why shouldn't I explore that option? I just wondered if someone had experience with or standards regarding this issue.

 

[jraef]

It's not the bus that is the problem, it's the insulating materials. Bus duct (if that's what they used) would have fault bracing, in other words the way they hold the bus bars in space is not willy-nilly, it is engineered to withstand the mechanical forces of the magnetic attraction / repulsion that takes place during a fault. ANY compromise to the structural integrity of that bus bracing makes it virtually unusable. Nobody if going to publish a procedure to rebuild bus structures after being potentially compromised by fire. The risk of flash over from surface conduction over carbonized material coating the insulators is also a serious concern.

If the bus feed was custom made, I wouldn't re-use it anyway. In the "olden days" things like that were done without a lot of design and testing. Insurance companies like to see things like UL listing now.

Waste of time in my opinion. Better off with the scrap value.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[JD0the0EE]

Thanks for the all the input.

 

[alehman]

If this is modern "sandwich" style busway, I wouldn't try to use any of it that was anywhere near the fire. It's really impossible to clean and all it takes is a little invisible carbon residue and moisture for a recipe for another mess like in your photo.

Alan
“The engineer's first problem in any design situation is to discover what the problem really is.” Unk.