add bracing to existing LV MCC 3

[ePOWEReng]

Does anyone have experience increasing the rating of an existing 480V MCC via installing additional bracing for on the bus (e.g. 45kA rms to 65 kA rms)?

Is this a via alternative to installing a new MCC? Any technical papers on this subject?

Thanks for your responses!

 

[dpc]

Unless you're prepared to do the short circuit tests, I don't see this as a reasonable option. I don't think any MCC supplier is going to sell you a field kit to do this.

You'd also have to deal with breaker ratings, of course. If the fault current increase is not too great, a current-limiting reactor could be used.

 

[jraef]

I agree. Even though you could technically do it, if you had to officially meet some sort of standard, your efforts would be futile because nobody is going to certify it after the fact. Even the original manufacturer would not be allowed to do that in the field without retesting.

And dpc's point about the individual bucket labeling is valid as well. If the MCC bus is braced for 45kAIC, chances are the buckets are not rated higher than that anyway.

 

[jraef]

Actually, you could technically do it on SOME brands, but not all of them. The Allen Bradley Centerline MCC bus bracing is a one-piece molded unit. There is nothing you could add to increase the bracing. You would need to replace the entire insulation structure. Probably cheaper to buy a new MCC.

 

[davidbeach]

Probably cheaper to install a reactor, or 1:1 transformer ahead of the MCC to keep the fault duty below the MCC rating.