Field Tests on High-Capacity Station Circuit Breakers

The development of high-capacity air-blast breakers in this country has taken place without the background of operating experience which has attended the use of oil circuit breakers and has, therefore, emphasized the need for testing this equipment at levels comparable with the assigned interrupting ratings. Although field short-circuit tests to verify circuit-breaker performance have been made on operating systems previously, they have been limited in most instances to moderate duty levels or, in the larger interrupting ratings, to the testing of high-voltage apparatus. Staging severe short-circuit tests at 15 kv introduces operating problems of greater significance since it virtually requires the application of the fault to the generating- station bus. This paper presents: 1. A résumé of the studies which indicated that it would be practicable to stage short-circuit tests ranging up to 2,000 megavolt-amperes directly on a particular generating-station bus. 2. A description of the physical plant equipment assembled for test purpose. 3. Operating experience during a series of 14 short circuits ranging from 200 to over 1,500 megavolt- amperes at 14.5 kv.