Improved fault protection for rural distribution systems

The use of automatic oil circuit reclosers on rural distribution lines has resulted in improved continuity of service as well as reduced maintenance cost. However, automatic circuit reclosers now in use are limited in application because of their inability to co-ordinate properly with fuses on the load side of the reclosers. An improved oil circuit recloser has been designed to incorporate the advantages of minimum time-delay opening on the first and second operations to clear all transient faults on the protected section, and greater time-delay opening on the third and fourth operations to allow the blowing of a sectionalizing or transformer fuse to isolate a permanent fault without causing a lockout of the recloser. A description is given of the design, operation, and advantages of this recloser which permits clearing of all transient line faults and isolates permanent faults by properly co-ordinating with sectionalizing fuses.