| 摘要 |
PROBLEM TO BE SOLVED: To improve the safety for preventing a public electrification fault, and to perform ground fault protection without fail.SOLUTION: A backup ground-fault protection device comprises a switch which is connected to the ground at one end, and parallels off, from a power system, a compensation reactor into which a ground current generated, when a ground fault occurs on an electric line flows, or put it into the power system; and a control part which controls the switching of the switch and controls the disconnection or the power-on of a blocker. When it is determined that the ground fault has occurred, on the basis of a zero-phase voltage of a secondary-side bus bar, the control part determines whether there occurs an erroneous non-operation according to the operation status of a ground-fault direction relay; and when the erroneous non-operation is determined, the control part disconnects the blocker on a fault electric wire, while specifying the fault electric wire at which the ground fault has occurred, on the basis of the change in a zero-phase current which is generated by the parallel-off of the compensation reactor from the power system. |
