INCREASED PERFORMANCE OF CAPACITOR BANK CIRCUIT BREAKERSBY CONTROLLED OPENING

摘要

For the first time a statistical model of the dielectric withstand of the circuit breaker opening has been developed to assess the restrike probability and to allow quantitative statements of the influence of controlled opening on the restrike probability when de-energizing capacitor banks. The calculations show that even with conservative assumptions about the standard deviations, the restrike probability varies by several orders of magnitude with arcing time. In order to verify the theoretical findings, the cold gas characteristic of a SF_6 circuit breaker was measured by the use of a 160 Hz 1-cosine wave for different arcing times. The results indicate that a fixed arcing time of 2.8 ms results in an increase of test voltage of 15% and the use of the circuit breaker at frequencies of 66 Hz (compared to 50 Hz) as predicted/supported by the calculation of the restrike probability in theory. Henceforth, the restrike probability of a circuit breaker can be assessed by the use of the given test procedure and the mathematical model and the potential for increased performance of capacitor bank circuit breakers by controlled switching can be determined.