A summary of the final results and conclusions of the second international enquiry on the reliability of high voltage circuit-breakers

CIGRE Working Group 13.06 (Reliability of High Voltage Circuit-Breakers) carried out world-wide reliability studies on high-voltage circuit-breakers during the fifteen year period 1971-1985. An important part of these activities was to conduct the first international enquiry on circuit-breaker failures and defects in service, this included circuit-breakers of all technologies. In 1986 a new CIGRE Working Group 13.06 was set up with one of its principle objectives being to conduct a second international enquiry on the reliability of high voltage circuit-breakers, The second enquiry was limited to single pressure SF₆ gas circuit-breakers placed in service after 1 January 1978 and with a rated voltage of 72.5 kV and above. The enquiry covered the period 1 January 1988 to 31 December 1991. A total of 70708 circuit-breaker years were included in the enquiry from 132 utilities in 22 countries. The details of the survey are discussed