Influence of interrupted current amplitude on the residual current and gap recovery after current zero

For commercial vacuum circuit interrupter valves with radial field contact the postarc current (PAC) waveshape was measured after short circuit current interruption applying a transient recovery voltage (TRV) of about 15 kV/μs (RRRV). Keeping the current decline di/dt at current zero constant, the power frequency (PF) current amplitude I_PF was varied from 0.5 up to 2 times the rated short circuit current. Significant influence of I_PF on the gaps memory is shown in particular effecting the post arc current duration which varies in a range between 2 and 8 μs. Based on the existing physical models an interpretation of the results is given. It is shown that the memory effect influences the gap recovery time