Controlled pulsed injection for HV gas blast circuit breakers

Abstract

According to modern trends, the interrupting performance and reliability of HV gas blast circuit breakers should be increased with transition to SF6-free technologies. Controlled switching is a promising method to reach it. However, high level of failure of the operating mechanism (drives) hinders this goal and would also result in the serious accidents. Some problems of the controlled switching application are discussed in the present study. A method of a short time gas pulse under high pressure – synchronous gas injection – is proposed to achieve the necessary cooling-heating balance in a thermal mode considering benefits and drawbacks of the controlled switching. The controlled pulsed injection should be introduced to the plasma region before current zero to decrease pre-zero arc conductivity and achieve the effective arc-gas interactions immediately after current zero. In the study the performance of the suggested approach is verified by numerical simulation and empirical relationships with a model mono-flow arc quenching device. The research confirms the synchronous gas injection has a wide perspective to increase breaking capacity of realistic circuit breakers in high voltage levels, especially for short-circuit interrupting.