A semi-empirical algorithm for determining the impulse characteristics of gas-insulated two-electrode systems in the vicinity of Paschen minimum with and without taking into account the spark channel thermoionization time

Abstract

The impulse characteristic represents the response of the gas insulation to the impulse load. There is no rational way to determine it, since it must include all pulse shapes and all probability quantiles of a random breakdown event. Near Paschen minimum is the operating point of gas surge arresters. For this reason, the results presented in this paper are important for the coordination of insulation at the low-voltage level. The semi-empirical algorithm derived in this paper is simple and allows obtaining impulse characteristics based on a small number of measurements. The paper presents two variants of the derived algorithm. One with and one without taking into account the thermoionization time of the streamer channel. Both variants were experimentally verified in well-controlled laboratory conditions and good results were obtained from the point of view of engineering practice. Of course, the algorithm which includes the thermoionization time of the spark channel gave more exact results. However, even in that case, an improvement can be made by observing the thermoionization process as a stochastic phenomenon. In this sense, suggestions for further improvement of the proposed algorithm are given.