New Developments in High-Voltage Minimum Oil Circuit Breakers

A new restrike-free, fast-acting, minimum oil circuit breaker for the range 60 to 500 kV is described. The breaker can be equipped with interrupters for either 40 000 or 60 000 amperes, providing a maximum symmetrical interrupting capacity of 50 000 MVA. Of the modular type, it is built from self-contained, identical, and interchangeable basic building elements. Arcing time is virtually independent of the interrupted current, an achievement attributed to an effective oil injection. Fully hydraulic operation of the contacts eliminates the use of mechanical transmission and springs. Test results are summarized that confirm that the breaker's performance exceeds standard requirements. Of particular interest is its insensitivity to high rates of recovery voltage.