Pacificorp

Dean H Miller

Bradley R Williams

C Thomas Eyford, Iii

A feeder restoration method starts in response to an overcurrent fault on a feeder (22) that causes a circuit breaker (42) to trip open, reclose once, trip again, and attempt to reclose again. During the time period between the first and second reclosings, any remote sectionalizing switches (46) on the faulty feeder are opened if they have also sensed the overcurrent fault, and a substation processor (50) evaluates the status of the faulty feeder and an alternate feeder (32, 34). After the second trip of the circuit breaker, the processor verifies whether the remote sectionalizing switch was closed and a remote tie switch (40) to the alternate feeder was open. If the circuit breaker locks open, the substation processor determines whether the remote sectionalizing switch did not sense the overcurrent condition (which indicates that the fault is between the circuit breaker and the sectionalizing switch) or simply failed to open. The processor then verifies that the remote sectionalizing switch voltage is zero and opens the switch. The processor next determines whether the alternate feeder and its associated transformer (30) and circuit breaker (44) can pick up the dropped load, and if they can, the substation processor modifies the alternate circuit breaker trip current settings to accommodate the new total load plus a surge current and closes the remote tie switch to transfer the load to the alternate feeder.

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Portland, OR, United States of America

Dean H Miller