FIELD: electrical engineering.
SUBSTANCE: proposed method includes connection of phase lead placed at highest voltage to ground with ground connection through first resistor at the same time connecting phase lead placed at lowest voltage to ground with ground connection through second resistor; measurement of current leakage to ground and phase voltages; evaluation of mains insulation resistance to ground and comparison of measurement result with admissible value; if it is below admissible value, signal is generated for disconnecting faulty component from mains; insulation resistance values are recorded at definite time moments and used to evaluate future insulation resistance value which is compared with admissible one; if it occurs below the latter, signal informing about probable approaching accident is generated, each newly recorded insulation resistance value being used for next calculation of future insulation resistance value; residual life of insulation is evaluated; configuration of mains under check at current resistance value recording moment, as found by condition of switching apparatus contacts, is included in calculations of future insulation resistance values; insulation is checked for inadmissible temperature rise, and check results are used to evaluate residual life of insulation basing on mechanism of insulation thermal aging.
EFFECT: enhanced operating reliability of mains under check due to enhanced sensitivity and selectivity of protective gear.
3 cl, 2 dwg
