Urgent Help - Circuit breaker sizing
Urgent Help - Circuit breaker sizing
(OP)
Hi,
I am new to circuit breakers sizing and selection; I have been looking at an existing PLC panel schematic and trying to make sense of the design. I attached a snapshot sample schematic.
1) I am interested to find out from anyone as to how the design engineer has arrived to the nominated circuit breakers value and type.
2) Additionally, I would like to know what function would each CB play in the schematic. The CBs are tagged as CB10, CB12, CB24, CB28, CB24, CB58.
I would really appreciate if anyone could provide some help on this matter. Many thanks
I am new to circuit breakers sizing and selection; I have been looking at an existing PLC panel schematic and trying to make sense of the design. I attached a snapshot sample schematic.
1) I am interested to find out from anyone as to how the design engineer has arrived to the nominated circuit breakers value and type.
2) Additionally, I would like to know what function would each CB play in the schematic. The CBs are tagged as CB10, CB12, CB24, CB28, CB24, CB58.
I would really appreciate if anyone could provide some help on this matter. Many thanks





RE: Urgent Help - Circuit breaker sizing
Rafiq Bulsara
http://www.srengineersct.com
RE: Urgent Help - Circuit breaker sizing
He also seems to be using them as isolation switches, but to be honest, it looks a little "breaker happy" to me. He shows the 110VAC as L1 and L2, but 110VAC is almost always North America, in which case one side (L2 most likely) would be a grounded Neutral. I would not switch a grounded Neutral and in fact depending on where the installation is, that may not be permitted. But maybe it's not in North America or this is some sort of specialized equipment that requires it...
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RE: Urgent Help - Circuit breaker sizing
David Castor
www.cvoes.com
RE: Urgent Help - Circuit breaker sizing
Jraef is correct in the consideration in upon known loading. Also, you have to factor in available breaker sizes and rating. IE if you sized it for 9A and one is not made in that size, you would need a 10A. Also, breakers of this size are normally thermal or thermal-mag having a rating of only 80% meaning a 10A breaker is only rated for 8A.
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