Application of single phase sectionalizers with three-phase reclosers to increase reliability

Until recently, one of the only viable rural or suburban feeder protection schemes beyond the loading limits of the 70-amp hydraulic Automatic Circuit Recloser (recloser) involved the use of a three phase electronic recloser with phase and ground curve settings. The three phase reclosers could only operate as three phase or single phase reclose and three phase lockout. On feeders that connected many single phase customers, this three phase operating characteristic proved to be costly with respect to reliability and, more specifically, to the number of customers experiencing an outage. The fault on one conductor of the three phase line from a substation would affect the other two phases until a crew could isolate the fault and reenergize the recloser. This report summarizes the investigation of using single phase sectionalizers on the load side of the three phase reclosers to provide sectionalizing of the faulted phase while leaving the other two phases energized.