A Dual Enhancement Switching Technology for Vacuum Circuit Breakers in Various AC-Based Operational Environments

Abstract

Vacuum circuit breakers (VCBs) have gained the attention of the medium voltage community for their involvement in various applications. However, the problem of arc-reignition is still under investigation with R-C snubber circuits considered as the most widely accepted solution. The RC circuits are connected in addition to the VCB to mitigate the resulting transient recovery voltage (TRV) and prevent arc-reignitions. A problem still lies in which some switching cases still suffer from arc-reignitions. To overcome this problem, a dual-enhancement switching technology is proposed in this paper. The dual-enhancement technology relies on using R-C and L-C to effectively enhance both the rate of rise of dielectric strength (RRDS) and high frequency current quenching capability (HFQC) respectively. A computational algorithm based on mathematical formulation was provided to accurately define the L and C values. The proposed technology was tested into two testing systems; a wind farm and industrial system. The results showed that the proposed switching technology (using LC and RC) was capable of reducing the TRV compared to the cases using RC only by 65.26 % and 7.46 % for the studied wind farm and industrial systems respectively. Hence, it could be concluded that the proposed technology is capable of reducing TRVs in different systems while the percentage of reduction in TRV is dependent on the surrounding system. The main feature for this paper is covering a gap in literature where HFQC was neglected in arc suppression algorithms, by proposing a highly effective dual-enhancement switching technology to that enhances both RRDS and HFQC parameters.

Keywords

• Vacuum circuit breaker
• rate of rise of dielectric strength
• arc re-ignition