Abstract: A power system includes main circuit interrupters each having a load output, feeder circuit interrupters, a number of tie circuit interrupters, and a circuit. The circuit is structured to block communication, at least when at least one of the tie circuit interrupters has an open state between a first and a second of the main circuit interrupters, of a zone selective interlocking output of one of the feeder circuit interrupters having a line input electrically connected to the load output of the first main circuit interrupter to a zone selective interlocking input of the second main circuit interrupter, and of a zone selective interlocking output of a different one of the feeder circuit interrupters having a line input electrically connected to the load output of the second main circuit interrupter to a zone selective interlocking input of the first main circuit interrupter.

Abstract: A power system includes main circuit interrupters each having a load output, feeder circuit interrupters, a number of tie circuit interrupters, and a circuit. The circuit is structured to block communication, at least when at least one of the tie circuit interrupters has an open state between a first and a second of the main circuit interrupters, of a zone selective interlocking output of one of the feeder circuit interrupters having a line input electrically connected to the load output of the first main circuit interrupter to a zone selective interlocking input of the second main circuit interrupter, and of a zone selective interlocking output of a different one of the feeder circuit interrupters having a line input electrically connected to the load output of the second main circuit interrupter to a zone selective interlocking input of the first main circuit interrupter.

Abstract: A power system includes main circuit interrupters each having a load output, feeder circuit interrupters, a number of tie circuit interrupters, and a circuit. The circuit is structured to block communication, at least when at least one of the tie circuit interrupters has an open state between a first and a second of the main circuit interrupters, of a zone selective interlocking output of one of the feeder circuit interrupters having a line input electrically connected to the load output of the first main circuit interrupter to a zone selective interlocking input of the second main circuit interrupter, and of a zone selective interlocking output of a different one of the feeder circuit interrupters having a line input electrically connected to the load output of the second main circuit interrupter to a zone selective interlocking input of the first main circuit interrupter.

Abstract: A feeder power source for a network power system includes a network transformer having a delta three-phase primary winding and a three-phase secondary winding; a three-phase primary feeder electrically connected to the delta three-phase primary winding; a three-phase secondary bus electrically connected to the three-phase secondary winding; and a three-phase electrical switching apparatus structured to open and close the three-phase primary feeder. A network protector includes a network relay and a three-phase circuit breaker structured to open and close the three-phase secondary bus. A first circuit is electrically connected between at least one phase of the three-phase primary feeder and ground, and is structured to unbalance shunt impedance to the three-phase primary feeder ground. A second circuit detects a shift in system neutral and detects that the three-phase primary feeder is opened by the three-phase electrical switching apparatus.

Abstract: A power system includes main circuit interrupters each having a load output, feeder circuit interrupters, a number of tie circuit interrupters, and a circuit. The circuit is structured to block communication, at least when at least one of the tie circuit interrupters has an open state between a first and a second of the main circuit interrupters, of a zone selective interlocking output of one of the feeder circuit interrupters having a line input electrically connected to the load output of the first main circuit interrupter to a zone selective interlocking input of the second main circuit interrupter, and of a zone selective interlocking output of a different one of the feeder circuit interrupters having a line input electrically connected to the load output of the second main circuit interrupter to a zone selective interlocking input of the first main circuit interrupter.