Single-phase-grounding-fault type judgment device for 35kV distribution network
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The utility model discloses a single-phase-grounding-fault type judgment device for a 35kV distribution network. The device includes three judgment units which are identical in structure. Each judgment unit includes a signal acquisition module connected with a voltage transformer of the 35kV distribution network. In each judgment unit, the signal acquisition module is connected with a rectifying module, an output end of the rectifying module is connected with an identical-phase end of a voltage comparator, and an output end of the voltage comparator is connected with a counter. Three counter top-digit output ends of the three judgment units are connected with three input ends of a three-input AND gate respectively and an output end of the three-input AND gate is connected with a first pole of a current amplifying device. A second pole of the current amplifying device is connected with a DC power supply. A third pole of the current amplifying device is grounded after being serially connected with a coil of a relay. Contact points of the relay are connected with an arc suspension coil of the 35kV distribution network. The device is capable of judging rapidly and effectively that whether a single-phase grounding fault of the 35kV distribution network is a permanent grounding fault or an intermittent electric-arc grounding fault.