In this scheme, three circuit breakers are used for controlling two circuits which are connected between two bus bars. Normally, both the bus bars are in service. A fault on any one of the bus bars is cleared by opening of the associated circuit breakers connected to the faulty bus bar without affecting continuity of supply. Similarly, any circuit breaker can be taken out for maintenance without causing interruption. Load transfer is achieved through the breakers and, therefore, the operation is simple. However, protective relaying is somewhat more involved as the central (tie) breaker has to be responsive to troubles on either feeder in the correct sequence. Besides, each element of the bay has to be rated for carrying the currents of two feeders to meet the requirement of various switching operations which increases the cost. The breaker and a half scheme is best for those substations which handle large quantities...