Development and Test of a 252 kV Multi-breaks Bus-tie Fast Vacuum Circuit Breaker

After the short-circuit fault occurs, bus-tie circuit breaker opens to isolate the faulty transmission line. Fast vacuum circuit breaker (FVCB) has the advantages of short opening time and high opening velocity, which makes the FVCB become an excellent bus-tie circuit breaker. The objective of this paper is to present the development and test results of a three-phase 252 kV multi-breaks bus-tie fast vacuum circuit breaker. Generally, each phase of the 252 kV FVCB was consist of four FVCB units connected in series. Each FVCB unit contained a vacuum circuit breaker driven by an electromagnetic repulsion mechanism and a grading capacitor of 400 nF connected in parallel. Test results showed that the average opening velocity of the FVCB unit was 6.5 m/s. The opening time of the FVCB unit was 1.1 ms with a variation of 0.2 ms, which ensured that all the FVCB units open synchronously. The 252 kV FVCB has successfully accomplished a series tests according with IEC 62271-100: 2008 and IEC 62271-1: 2007, which includes: insulation test, terminal fault test et al. With the application of bus-tie fast vacuum circuit breaker, the fault current flowing in the faulty line could be rapidly limited after the short-circuit fault.