Influence of interrupted current amplitude on the post-arc current and gaprecovery after current zero - Experiment and simulation

For commercial vacuum circuit interrupter valves with radial field contact, the post-are current (PAC) waveform was measured after short circuit curre nt interruption applying a transient recovery voltage (TRV) of about 15 kV/ s (RRRV), Keeping the current decline di/dt at current zero constant, the p ower frequency (PF) current amplitude I-PP; was varied from 0, 5 up to two times of the rated short circuit current. Significant influence of I-PP On the gaps memory is shown in particular effecting the post-are current durat ion which varies in a range between 2 and 8 mu s. Based on the existing phy sical models an interpretation of the results is given. It is shown that th e memory effect influences the gap recovery time. The experimental results were further used to determine the parameters of t he sheath growth model described by [9], The initial ion density is fitted according to the current ramp di/dt before current zero (CZ) and according to the measured Q(PP) = integral i(PP) x dt during the arcing phase. The re sults of two different test procedures were applied in order to separate th e effect of current ramp di/dt and Q(PP) = integral i(PP) x dt. The influen ce of both parameters and of the rate of rise of the recovery voltage du/dt (RRRV) on the sheath edge velocity could be demonstrated by simulation.