JPS54159650A - Selective ground-fault detection method for dc circuit - Google Patents

Abstract

PURPOSE: To selectively detect the ground-fault in distribution line by detecting continuous ground-fault current by zero-phase current transformer by earthing the neutral point of DC power source to supply power to plural distribution lines through an interrupted contact opening or closing at a definite period.

CONSTITUTION: The anode and cathode sides of the DC power source 1, from which power is supplied to plural distribution lines, are connected through the resistors 22 and 23 to the current relays 24 and 25 at a contact earthed through the interrupted contact 26. And, when a ground-fault occurred at the point 4 of No.1 distribution line, the current relay 25 operates to send out an alarm about a ground-fault on the outside cathode and then to open or close intermittently the interrupted contact 26 for interrupting the ground-fault current which is, in turn, taken out at the zero-phase current transformer 31 to operate the detector 32. Thus, the interrupted ground-fault current flows in the earthed distribution line alone, and the distribution line suffering ground-fault can therefore be detected selectively without interrupting sound distribution lines.

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