Molded Case Breakers for a Highly Variable Load
Molded Case Breakers for a Highly Variable Load
(OP)
I am in the planning stages of a project to replace the 480V switchgear for a process that can't tolerate much down time.
One approach we're considering is to set a temporary line-up of switchgear nearby, and move the loads to the temporary line-up while we remove and replace what's there.
The existing line-up uses draw-out gear, as will the new, permanent line-up. However, since the temporary gear will not be needed after the upgrade, our plan is to use molded case breakers.
What concerns me is that one of the process loads we're supporting has extreme fluctuations. On an analog current meter, it appears to swing between 0.5 MW and 1.5 MW every second or two. I suspect it may be fluctuating much faster than that and the analog meter is just not fast enough to show it.
Can molded case breakers support a load like this (assuming they are of the proper amperage) or is there a risk that they will trip?
One approach we're considering is to set a temporary line-up of switchgear nearby, and move the loads to the temporary line-up while we remove and replace what's there.
The existing line-up uses draw-out gear, as will the new, permanent line-up. However, since the temporary gear will not be needed after the upgrade, our plan is to use molded case breakers.
What concerns me is that one of the process loads we're supporting has extreme fluctuations. On an analog current meter, it appears to swing between 0.5 MW and 1.5 MW every second or two. I suspect it may be fluctuating much faster than that and the analog meter is just not fast enough to show it.
Can molded case breakers support a load like this (assuming they are of the proper amperage) or is there a risk that they will trip?






RE: Molded Case Breakers for a Highly Variable Load
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RE: Molded Case Breakers for a Highly Variable Load
RE: Molded Case Breakers for a Highly Variable Load
It sounds like it will probably work as long as I get MCCB's with adequate settings.
As far as upstream issues, this lineup is the heart of the facility, and it has a dedicated substation, so I should be protected I think.
RE: Molded Case Breakers for a Highly Variable Load
The fact that this has a dedicated substation should make you MORE nervous about it, not less. I highly suggest you contract the services of a qualified EE for this, even though it's temporary. You can't be temporarily burned or dead...
"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: Eng-Tips.com Forum Policies
RE: Molded Case Breakers for a Highly Variable Load
Thanks for the warning :)