Analysis of dynamic loop resistance disturbance characteristics of high voltage SF6 circuit breaker

Abstract

Dynamic loop resistance measurement is a contact diagnosis technology of high voltage SF6 circuit breaker. Due to the serious disturbance in the process of dynamic circuit resistance measurement, it is difficult to calculate its characteristic quantity, and seriously affects the evaluation of contact ablation state. By studying the dynamic loop resistance curve of high voltage SF6 circuit breaker under different ablation degrees, it was discovered that the disturbance phenomena on the dynamic loop resistance measurement curve are primarily of three types: fluctuation, narrow pulse (several times μs), and wide pulse (tens to hundreds of times μs). The simulation analysis results of the test circuit show that in the dynamic loop resistance measurement, the relative movement of the dynamic and static contacts causes the dynamic loop resistance fluctuation, which can reflect the surface shape of the contact; The current transfer between the main contact and the arc contact leads to a narrow pulse on the resistance waveform of the dynamic circuit, so the narrow pulse is the sign of the separation of the main contact; Contact bounce and arcing between arc contacts lead to wide pulse on the resistance waveform of dynamic circuit, so the wide pulse can be used as a sign of arc contact separation. Narrow pulse and wide pulse can be used as key characteristic quantities to calculate contact separation time and evaluate contact ablation state more accurately.