4. Cut-off time

4.1 General

Up to now, we've represented DC outage problems almost exclusively in the (u, i ) plane, which is interesting for understanding the phenomena, but devoid of the time scale.

As soon as we know Δu for each value of i, we can easily deduce the cut-off time. For a given evolution of arc voltage versus current, the cut-off time t _C is directly proportional to the circuit inductance L, since, according to the relation (3) : $t_{\text{C}}=L$