DEVICE FOR PROTECTING INSULATED-NEUTRAL THREE-PHASE SUPPLY MAINS AGAINST INTERNAL OVERVOLTAGES (ALTERNATIVES) Russian patent published in 2004 - IPC

FIELD: power engineering.

SUBSTANCE: proposed device designed for use in 3-6-10-35 kV insulated-neutral lines for effective restriction of arcing peak overvoltages during ground faults as well as for maintenance of minimal possible ground-fault current and self-elimination of arc-over in supply mains has sectionalized ground resistor incorporating two series-connected circuits one being commutated circuit and other, non-commutated one. Connected in parallel with ground-resistor commutated circuit is switch incorporating control unit and two thyristors connected in parallel opposition. As an alternative ground resistor may have series-connected sections of equal rating, one of them being non-commutated section. Connected in parallel with commutated sections is switch built around two thyristors connected in series opposition. First thyristor of switch is connected in parallel with commutated section of ground resistor. Second thyristor is connected in parallel with first commutated section. Cathodes of both thyristors are connected to center lead of ground-resistor commutated sections. Switch is provided with control unit that has relay module, control voltage module, and first control-voltage module. In addition resistor may have three series-connected sections of different ratings, one of them being non-commutated section.

EFFECT: enhanced operating reliability of ground-fault relay protective gear.

8 cl, 6 dwg