预电离间隙在不同气体介质中的正负极性击穿特性OA北大核心CSTPCD

The breakdown characteristics of trigger gap for the pre-ionization switch in N2,the mixture of N2 and SF6 and SF6 atmosphere under positive and negative pulse were investigated for the higher voltage grade and bipolarity application.The relationships between the breakdown voltage and delay time of the pre-ionization gap and the pressure of different kinds of gases were obtained,and the breakdown characteristics were compared for the pre-ionization gap under positive and negative polarities.The results of the experiment demonstrated that the breakdown process of the gap in N2 was more stable,and the linearity of breakdown voltage varying with pressure in N2 was the best among the three kinds of gases.The breakdown voltage was saturated only in SF6 with the increase of gas pressure.The breakdown voltage of the gap under negative polarity was higher than that under the positive at some certain values of the pressure,and this phenomenon might suggest that there was a polarity effect upon the breakdown process of pre-ionization gap.Compared with the mixture and N2,the absolute differences between negative and positive polarity for both breakdown voltage and delay time in SF6 were relatively higher.N2 should be preferred as the insulating medium for the pre-ionization gap to reduce the synchronization delay difference of the bipolar self-triggered switches.The polarity effect of the pre-ionization gap and the distinctions among the different kinds of insulated gas medium should be paid more attention in engineering applications for the pre-ionization gap.