Breaking capacity of fuses

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The breaking capacity gives the current that a fuse is able to interrupt without being destroyed or causing an electric arc with unacceptable duration. The maximum short circuit current which can occur under fault conditions should not exceed the rated breaking capacity of the fuse. Otherwise breaking of the fault current cannot be guaranteed.

1 Choosing breaking capacity
2 Importance of breaking capacity
3 Common Breaking Capacities
4 See also

[edit] Choosing breaking capacity

Calculating a suitable breaking capacity involves determining the supply impedance and voltage. Supply impedance may be found by

measurement
reading datasheet
or the PSCC value requested from utility supply company

[edit] Importance of breaking capacity

Some applications have inherently limited and low PSCC, and in these cases often all available fault current protectors will suffice. This is typical for supplies from small & miniature transformers, which can have anything up to 33% regulation.

On the other hand some applications may tend to have high PSCCs, with fault currents able to do extensive damage and endanger human life. Breaking capacity is highly important in these cases. Examples include electrical substations.