FIELD: electrical engineering; single-phase ground fault protection of insulated-neutral three-phase mains.
SUBSTANCE: proposed method includes connection of phase having highest voltage to ground to ground circuit through first resistor at the same time connecting phase having lowest voltage to ground to ground circuit through second resistor; measurement of phase voltages and insulation resistance of supply mains to ground; comparison of this resistance with that permissible, and if it is below this value, off-signal is generated to turn off faulty component of mains; also recording of insulation resistance at definite time moments to determine next insulation resistance value, comparison of the latter with permissible value, and if it is found to be below permissible value, information signals is generated to warn about approach of probable accident moment; in the process each recorded insulation resistance value is used during calculations of next insulation resistances and, in addition, residual insulation life is determined.
EFFECT: enhanced operating reliability of supply mains under protection due to reducing level of disturbing actions caused by disconnection of supply mains faulty components.
3 cl, 3 dwg
