Analysis of SF6 Circuit Breakers Failures Related to Missing Current Zero. Part I.

Abstract

This paper describes aspects of switching capability of 126 kV SF6 puffer and auto-puffer interrupter types of circuit breakers during breaking of aperiodic current (DC component) resulting in such phenomena as missing current zero. It is shown that neither IEC/ANSI standards nor other technical brochures have requirements for circuit breakers in the condition of missing current zero. The review of 126 kV SF6 circuit breakers failures, operation problems and experimental data obtained during operation cycle on the substations in Russia are given. Experimental characteristics of pre-strike voltage for 126 kV SF6 circuit breaker at different filling pressures are shown. Current oscillograms of 126 kV SF6 circuit breakers failures related to missing current zero are presented. Simulation results of gas dynamic and thermal characteristics in condition of missing current zero are shown. The general countermeasures against prevention of circuit breakers failures related to missing current zero are given. This paper is the first part of the present research.