Re-insulating cracked old insulated bus bars in an MCC - anyone have an idea on how to do this ?

[bdn2004]

This company has an old Allis-Chambers 480V motor control center at their plant. It feeds the most critical loads in the Plant.
The insulated bus bars are cracked and in pieces.

Is there a way to re-do these? Is there a company that someone could recommend ?

 

[SilverfoxUK]

I have to hold my hand up and say I have used refurbished equipment but I would never consider a major expansion with refurbished but obsolete equipment.

Taking the health and safety executives position in the event of an incident where someone ended up badly burnt I think it would reasonable to ask why you decided to pay as much money if not more for equipment that wasn't up to modern standards and by this I'm suggesting arc flash protection.

In the UK we can claim grandfathers right where we maintain equipment to the standard to which it was originally installed. This does not include new kit that must meet current safety standards.

I agree you can often fit alternative manufacturers kit to an existing board but again its not best practice.

Trying to source obsolete kit can be a nightmare. I'm guessing many people have been driven to the likes of the Bay to make purchases. The equipment is obsolete for a reason. Square D have stopped making it for a reason. Time to stop being sentimental about kit you have grown up with and look to new.

 

[bdn2004]

Silver,

I didn't design these systems. But I understand the logic on both.

If you are a small business, spending $200,000 may just eat your entire profit for a year. And for something that's working perfectly fine - that ain't happening - that's just reality.

In the other case - When you've got a plant with close to 30 identical switchgears, with never a safety issue ever with any of them, and scheduled annual maintenance from outside qualified people...it's not a bad call to buy the exact same gear.

 

[waross]

Many years ago I was called out to a sawmill sometime after midnight. There had been a flash-over in one section of an MCC. Dust buildup on the insulators for the vertical bus.
The damage was near the bottom of the section and the lowest bucket was fairly tall and connected to the bus bars above the damaged parts.
I had the damaged bus bars trimmed and removed with a hacksaw. Everything tested clear.
We re-energized without a problem.
The operator started re-starting his machines. I speculated that there was a splash of molten aluminum adhering to the back of a bucket where it was not readily visible. I believe that the splash of aluminum was jolted loose by the shock of a large contactor closing.
When the largest motor was started, there was a flash and the lights went out. Then for several seconds we were entertained by the sight of an MCC in the dark, with all the joints lit up a brilliant white from the internal arcs.
This time the damage was more extensive.
We now had two or three hours before the main mill started for the day shift. Without one conveyor controlled by the affected MCC the main mill would shut down in about 15 minutes.
We removed the vertical bars completely and installed cable drops to each bucket as we replaced the buckets.
We had the MCC repaired and back online with seconds to spare. (In the dark)
The point is that you may hit a sweet spot between down-time and expense by replacing the vertical drops with cables and re-insulating the horizontal bus.
Another option is to replace all the bus with cables.
When you are between a rock (management and budgets) and a hard place (failing obsolete equipment) you may have to think outside the box.



Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[bdn2004]

Waross,

That’s a good idea, especially if the Plant guys were doing it in a critical unplanned Emergency situation.

I passed on these ideas. And we’ve already found a couple of guys that specialize in this kind of work. There’s an ABB shop in this town that does nothing but revamp or maintain big breaker for all the local industry. They knew guys that do this kind of work.

Thanks