DEVICE FOR MONITORING THREE-PHASE LINE AND PROTECTING IT AGAINST DANGEROUS VOLTAGE FLUCTUATIONS Russian patent published in 1999 - IPC

FIELD: power engineering. SUBSTANCE: device designed for protecting three-phase lines rated both above and below 1000 V upon occurrence of emergency voltage drop, ground faults, phase failure, etc. has primary voltage measuring transducer, reverse-, forward-, and zero-sequence filters, phase and zero- sequence voltage indicators. Novelty is that primary voltage measuring transducer is built up of three-arm balanced asymmeter each of whose arms has series-connected phase coil, metal tube covered inside and outside with insulating material, gaseous-discharge lamp, and resistor; phase coils of each arm made of flexible insulated stranded conductor are wound on sections of insulated conductor sections of respective phases of three-phase line under control and are electrically insulated from them; transducer sensitivity and unbalance control is effected by varying phase coil turn number. EFFECT: reduced mass and size, simplified design and circuit arrangement, and improved safety of device. 3 cl, 1 dwg