Tests on 138-kv high-speed oil circuit breaker

WHAT is believed to be the heaviest fault interruption ever made at 138 kv was attained during field tests on July 3, 1954, at the 600-megawatt Philip Sporn Power Plant of American Gas and Electric Company when a 138-kv 1,200-ampere (amp) 5,000-megavolt-ampere (mva) 3-cycle oil circuit breaker of standard design (Fig. 1) interrupted 6,900 mva under normal tripping conditions; that is, pretripping was not resorted to for obtaining a large numerical value of power. Asymmetry for this interruption was 49.5 per cent. The breaker interrupted all power available at the site, including that received from distant stations as shown in Fig. 2. A comparison of the 6,900-mva value with the 3,500 mva interrupted 10 years ago at Philo Station points to the rapid growth of the system.¹