Study of the post-recovery current in SF₆circuit breakers

Abstract

A sustained current conduction in the breaking chamber after a current interruption has been observed. This current, which we named 'Post-recovery (PR) current', is in phase with the applied voltage and its value ranges from several milliamps up to several amps. The present study shows that the probable origin of the PR current is an ionic conduction of SF6 between the contacts. The estimated temperature of the conducting gas is about approximately 2000 K. The evolution of the temperature is in good accordance with a computational model based on the resolution of two-dimensional Navier-Stokes equations.

- circuit-breaker arc modelling around current zero: I. Free-recovery simulation using a collisional-radiative plasma model

“…Although it is found that the concentrations of S + 2 and F − species depend very strongly on the temperature at later stages, we also found in both cases that these ions remain in the arcing space for a long time, giving rise to the possibility of an ionic current whenever an electrical field is applied over the recovering plasma, as investigated by Maftoul et al [18]. In the uni-directional case the ion SF + takes over from S + 2 after around 1 ms to guarantee charge neutrality.…”

Medium-Voltage Load Current Interruption in the Presence of Ablating Polymer Material

“…In [16], Maftoul et al report on a current after arc extinction that exceeds the 10 0 -10 2 -µs period of a typical post-arc current, and name it 'post-recovery' current. Although differing in current rating (24 and 41 kA) and gas (SF6), the observation of a continued current of a few tens of milliamps is similar to ours.…”

Evaluation of Parameters Affecting Arc Plasma Chute in a Typical Gas Interrupter

“…10) The arc is represented as a BBM because it is based on observed data. BBMs are mathematical descriptions of the electrical properties of the arc only and cannot simulate the complex physical processes inside the circuit breaker.…”

“…The first methods use a representation of the breaking arc as a nonlinear resistance and consider its interaction with the external electrical circuit. 10) The arc is represented as a BBM because it is based on observed data. BBMs are mathematical descriptions of the electrical properties of the arc only and cannot simulate the complex physical processes inside the circuit breaker.…”