Plain definition you can send to a customer
Pre-arcing I²t (melting I²t): the total heat accumulated while the element heats up to the point of melting, before any arc is drawn.
Arcing I²t: the heat generated from the moment the arc forms across the break until it is extinguished and the circuit is fully interrupted.
Total I²t = pre-arcing I²t + arcing I²t.
Two core functions in PV DC circuits
Preventing nuisance operation
The larger the pre-arcing I²t, the better the fuse withstands PV surges and reverse impulses — sun/cloud transitions and weak faults are far less likely to melt the element unnecessarily.
Selective protection between levels
The downstream device — the inline fuse at the string — must have a lower pre-arcing I²t than the upstream fuse or breaker. Only then does a string fault clear locally instead of tripping the whole combiner box.
How to apply it when specifying
YePV supplies both the inline fuse connectors and the matched gPV elements, so the discrimination study stays consistent from string to combiner box.
