Influence of the electrode parameters on the pulse shape characteristic at small pressure and inter-electrode gap values

Abstract

Gas filled surge arresters (GFSA) has working point close to minimum on Paschen curve. Below that point breakdown follows Townsend's mechanism, i.e. the secondary processes on the electrodes dominate the secondary processes in the gas. The most important parameter of GFSA is its pulse shape characteristic. The main problem in GFSA application is its delayed response. The built-in radioactive sources cause the significant improvement of GFSA characteristic. On the other hand, the use of GFSA with radioactive filling would be some-what danger to the environment. Specific problems arise from inade-quate procedure regulating for storage and destruction for GFSA with radioactive filling. The narrower the pulse characteristic is, the smaller response time is, i.e. the better protective characteristic of GFSA is. The aim of this paper is to present the electrode effects as approach for the improvement of GFSA protective characteristics in the most optimal way. In that purpose, we examined the influence of the electrode parameters on the pulse shape characteristics. As variable parameters, we used the electrode material and the manner of electrode surface processing. The electrodes were made either of copper, of aluminum or of electrons. The materials with higher values of output work corresponds larger pulse shape characteristics. In the case of investigation the influence of the manner of processing electrode surface on pulse shape characteristics, the electrodes were made of brass with polished, sand-processed or engraved. By applying the "area law" it is possible to determine the pulse shape characteristic based on single series of measurements (using single shape of the pulse voltage). An original analytical algorithm has been developed to determine and compare characteristics of GFSA for a pulse shape characteristic.