Metal-Clad Switchgear for 23 and 34.5 kV

The extension of metal-clad switchgear with oilless power circuit breakers to the higher voltages of 23 kV and 34.5 kV has awaited the development of a suitable circuit breaker unit. Prompted by the need of Duquesne Light Company for such 23-kV equipment for their new Oakland substation, the breakers described in this article were designed and developed. As a result, indoor and outdoor metal-clad switchgear, with all of their well- known advantages, are now available for both voltage ratings up to a 1500-MVA interrupting rating and for continuous current ratings of 1200 and 3000 amperes.