mcb
- Thread starter power tr
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- Chapel Hill, NC
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- Retired Electrical Contractor
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petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
Appears to be a couple of fused power circuits.
I believe those are manual motor protectors with thermal and magnetic trip. The thermal trip is indicated by the square wave. The magnetic should normally be indicated by I> in IEC schema but this one apparently uses a half circle? The symbol to the right is a NC aux contact.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
You might be right. But normally the manual operator part of such a device would also be shown in the schematic and this does not show the manual operator. I'm pretty sure it's not a fuse now than I look at it closer. I was thinking it was some kind of a fused switch with an auxiliary but I don't think that's what it is anymore. I think it is some kind of circuit breaker.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
I did some more digging. It appears to be a circuit breaker drawn according to the latest IEC standard IEC 60617.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
What don't you understand about that? You have 3 phase 4 wire power coming into a terminal block X401 terminals 12 though 18, then it is split to feed two MCBs, F421 and F422, which then feed two separate 3 phase loads though terminal block X401, but terminals 19 through 26. Then in some other panel, the two 3 phase 4 wire circuits terminate on another terminal block, also (poorly designed) X401, terminals 5 through 12.
Side note: X401 may not be a terminal block number designation, it may be a type number.
Side note: X401 may not be a terminal block number designation, it may be a type number.
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