The Analytical Study of the Controlled Switching of an AC Vacuum Circuit Breaker for Fault Interruption

This paper presents the findings from the analysis of an indoor Alternating Current (AC) Medium Voltage (MV) Vacuum Circuit Breaker (VCB) during fault interruption when connected to a MV power line. The circuit breaker fault interruption phenomenon was investigated during Phase-to-Earth faults. This concept was simulated using an electromagnetic transient program (EMTP). An analysis was conducted when advanced controlled switching (ACS) technology was applied to the circuit breaker to achieve current zero (CZ) tripping. CZ tripping during fault interruption was successfully achieved, with the simulation results indicating a reduced arcing current, voltage and a reduction in transient recovery voltage (TRV). The results demonstrated an improved lifecycle of the circuit breaker when compared to a non-controlled conventional circuit breaker.