Do current limiting MCBs differ from Type B, Type C MCBs?
The French load limiter is more like an MCB with a very accurately set trip limit, but designed to be operated many times by modest overload ,not just the occasional high value fault.
A current limiting breaker on the other hand is for systems with high PSSC and acts more like an HRC fuse, in that it cuts off fast enough to take the edge off the energy let-through.
Actually to a degree all MCBs act in this way, but not very impressively as at very high currents the breaking time stops getting faster, so let-through energy tends to rise with ~PSSC - but then it does a bit with some designs of fuse as well - in all cases it all depends how the arc is quenched.
BIG circuit breakers sometimes do things with compressed air and magnets to chop the arc up as it forms or to direct it onto a series of blades.
Mike,
The French load limiter is more like an MCB with a very accurately set trip limit, but designed to be operated many times by modest overload ,not just the occasional high value fault.
A current limiting breaker on the other hand is for systems with high PSSC and acts more like an HRC fuse, in that it cuts off fast enough to take the edge off the energy let-through.
Actually to a degree all MCBs act in this way, but not very impressively as at very high currents the breaking time stops getting faster, so let-through energy tends to rise with ~PSSC - but then it does a bit with some designs of fuse as well - in all cases it all depends how the arc is quenched.
BIG circuit breakers sometimes do things with compressed air and magnets to chop the arc up as it forms or to direct it onto a series of blades.
Mike,
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