A synthetic circuit is used in tests to measure and research 35kV exposed shield vacu-um interrupters with cupped axial magnetic field type electrodes. The experimental results under vari-ous separation showed that there is a limitation of the best separation for 35kV vacuum interrupters. In this range

the probability of reignition is lower and the post zero withstand-voltage is higher. This pa-per analyzes the experimental results and points out that it is necessary to reduce the electrode separa-tion of domestic vacuum interrupters.