GROUND-FAULT PROTECTION COORDINATING SYSTEM AND GROUND-FAULT CIRCUIT INTERRUPTER WITH GROUND-FAULT PROTECTION COORDINATING UNIT

A hierarchical stage in a power distribution system to which an earth-fault-protection apparatus 40 is connected is set by hierarchical stage level setting means 42, and a carrier signal indicating a hierarchical stage level is output to a power distribution line 1 when any earth fault detection signal is sent from carrier transmission means 43 through power distribution line carrier communication. A carrier signal from the other earth-fault-protection apparatus is detected by carrier detection means 44, and an interrupt operation is switched and interlocked to a time-delay operation when any signal indicating a lower level than its hierarchical stage level is present in the carrier signals; and the interrupt operation is switched and interlocked to an instant interrupt operation when any signal indicating a lower level than its hierarchical stage level is absent.