Nine years' experience with ultrahigh-speed reclosing of high-voltage transmission lines

Data covering nine years' operating experience with 91 ultrahigh-speed-reclosing breaker installations mainly on a large interconnected and integrated high-voltage system are presented and analyzed: out of 635 cases of flashover cited, 570 reclosures were successful and 65 cases of reclosure were unsuccessful, a record of 89.8-per-cent successful reclosure. Double-circuit lines show a record of unsuccessful reclosure double the average but 80 per cent of the apparently unsuccessful reclosures resulted in successful reclosure of one circuit. The conclusions drawn are that ultra-rapid reclosure has proved itself a tool of major importance for use in improving high-voltage line reliability; that its use can, and should be, extended to lower-voltage lines, and that further improvements are in sight as a result of recent improvements in circuit-breaker opening and reclosure time.