Interrupting rating (RMS Symmetrical)
Interrupting rating (RMS Symmetrical)
(OP)
Hi all,
found these doubt, hopefully someone can help me with these?
1. in MCC, for the bus bracing (RMS Symmetrical), if the requirement needs 22 kA, can 42 kA works for this and why?
2. Still in MCC, if combination starter unit has : (a)unit interrupting rating and (b) ambient complression over-load to be 22 kA RMS Sym, can 42 or 65 kA work for this?
my thought is that for the bus, it is okay if the design exceed 22 kA, but for starter unit...i don't know...
thanks before...
found these doubt, hopefully someone can help me with these?
1. in MCC, for the bus bracing (RMS Symmetrical), if the requirement needs 22 kA, can 42 kA works for this and why?
2. Still in MCC, if combination starter unit has : (a)unit interrupting rating and (b) ambient complression over-load to be 22 kA RMS Sym, can 42 or 65 kA work for this?
my thought is that for the bus, it is okay if the design exceed 22 kA, but for starter unit...i don't know...
thanks before...





RE: Interrupting rating (RMS Symmetrical)
Think of the rated SCCR as "strength" of the equipment to withstand electro-mechanical forces( for a short period of time until the OCPD opens). So as long as the rated strength is equal or greater than required, you are good.
RE: Interrupting rating (RMS Symmetrical)
You should not use 25 kA tared equipment on a system supplying 42 kA.
You may use 42 kA equipment in place of 25 kA equipment on a system with 25 kA or less available fault current.
Bill
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"Why not the best?"
Jimmy Carter
RE: Interrupting rating (RMS Symmetrical)
Right, but it will cost you more money.
RE: Interrupting rating (RMS Symmetrical)
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