DEVICE FOR PROTECTION AGAINST SINGLE-PHASE EARTH FAULTS IN NETWORKS WITH INSULATED NEUTRAL AND WITH COMPENSATION OF CAPACITANCE CURRENTS Russian patent published in 2019 - IPC H02H3/16 

FIELD: electrical equipment.

SUBSTANCE: field of application: electrical equipment. Device for protection against single-phase earth faults in networks with insulated neutral and with compensation of capacitance currents has zero-sequence current sensor on each line, output of which is connected to inputs of the first and second band-pass frequency filters, outputs of connected to first and second inputs of first switching unit, measuring transformer of zero sequence voltage, output of which is connected to inputs of the third and fourth band-pass frequency filters, outputs of connected to first and second inputs of second switching unit, by output connected to input of differentiator, and time delay element for actuation, additionally comprises linear conversion unit, first and second correlators, division unit, unit for calculating absolute value, first and second comparison elements, third and fourth switching units, OR logic element, starting member for zero-sequence voltage and logic element AND, wherein the first input of the first correlator is connected to the output of the first switching unit, the second input of the first correlator and the first and second inputs of the second correlator are connected through a linear conversion unit to the output of the differentiator, output of first correlator is connected to first input of divider, output of second correlator is connected to second input of divider unit, output connected to input of first comparator element and through the unit for calculating the absolute value - with the input of the second comparison element, whose outputs through the third and fourth switching units are respectively connected to the inputs of the OR logic element, by the input of the AND logic element connected to the first input, the second input of which is connected to the output of the starting member by zero sequence voltage, by the input connected to the output of the measuring transformer of the zero sequence voltage, wherein output of AND logic element is connected to input of time delay element for actuation.

EFFECT: technical result is high selectivity and sensitivity of protection from earth faults and wider field of its possible application.

1 cl, 6 dwg