Reclosing relay for ring bus substations

RING buses as herein discussed are divided by circuit breakers into sections, each of which provides termination of a source or load. Each source or load may be connected to its section by a motor-operated air-break switch. Such a ring bus poses problems not encountered with a straight bus. A fault trips both circuit breakers of a section. When the circuit breakers trip, it is important that the ring be restored as rapidly as possible, since a true bus does not exist. If the ring should become open at another location, several problems may develop, depending on design. Generators can be isolated, the system split apart, relaying handicapped by separating zero-sequence sources, or loads dropped unnecessarily. It is important that a faulted line be isolated and the ring restored as rapidly as possible to shorten the vulnerable period. The best method of accomplishing this is to automatize the two circuit breakers and the air-break switch.