Mechanical simplicity of air-blast circuit breakers

THE papers heretofore presented before the Institute on the subject of air blast circuit breakers have covered primarily their advantages in comparison with oil circuit breakers, the principles involved in current interruption by air blast, descriptions of interrupters developed by several manufacturing companies, the results of tests and related data. It is considered opportune to give an account of several other types of air blast circuit breakers ranging in voltage from 4 kv to 230 kv as developed and built by certain manufacturing companies in Canada and the United States in collaboration w th a large power company. The first machine of this general type was a 138-kv air blast breaker placed in service in 1934 at the Beauharnois generating station on lines to Montreal, this breaker having continued in service for six years successfully interrupting all faults; three additional breakers of the same general design with improved details have been placed in service at this station in later years. Breakers of four types built by three manufacturing companies, all breakers having certain general features in common, will be illustrated by photographs and diagrams. In all of the breakers described, the general design of interrupting contacts is the same. This arrangement of contacts is suitable for the use of arc chutes utilizing any one of the elementary principles of pneumatic arc extinction or combinations of such principles.