High-Capacity ``Hydro-Blast´´ Circuit Breaker ror Central-Station Service

The increasing demand for oilless circuit breakers has resulted in a number of contributions in that field. Outstanding among these from the standpoint of interrupting capacity at generator voltages is the ``hydro-blast´´ circuit breaker, which has been developed in ratings up to 1,500,000 kva. This breaker has the feature of complete interchangeability with the standard H-type oil circuit breaker and thus combines all of the well-known advantages of that type with the total absence of inflammable material. This paper describes in detail the construction and operation of the 500,000-kva hydro-blast circuit breaker for central-station service, several of which have been in service for over half a year.