The influence of parameters of gas-insulated system on the duration of electrical breakdown at points near to Paschen minimum

Abstract

The paper considers the time of thermoionization of the spark channel during gas breakdown in the vicinity of Paschen minimum. For the purposes of measuring the time of thermoionization, an experimental procedure was developed that enabled the measurement of times of the order of nanoseconds with a measurement uncertainty of less than 5%. The thermoionization time was measured to the right and to the left of the Paschen minimum. There were included the vacuum breakdown mechanism, the anomalous Paschen breakdown mechanism, the Tausend breakdown mechanism, and the streamer breakdown mechanism. The obtained results show that the thermoionization time is a stochastic quantity. It was established that the random variable thermoionization time belongs to a normal or Weibull distribution. The results also show how the insulation parameters affect the random variable thermoionization time. Experiments were performed with He, SF6 and N2 gases. The electrode system formed a homogeneous field (Rogowski-Rogowski) or an inhomogeneous field (spike-spike). The surfaces of the electrodes were either polished or sandblasted.