METHOD OF DETERMINING THE POINT AND DISTANCE TO SINGLE-PHASE GROUND FAULT IN 6-35 KV ELECTRIC NETWORKS WITH ISOLATED OR COMPENSATED NEUTRAL LINE Russian patent published in 2020 - IPC G01R31/08 

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering, in particular to methods of determining location of damages in 6–35 kV electric networks with isolated or compensated neutral. Method of determining the point and distance to single-phase ground fault in 6–35 kV electric networks with insulated or compensated neutral is that ballast resistance is connected to backup cell of busbar section, in which there is a short to ground, include high-voltage switch of backup cell, providing leak through ballast resistance of limited by value and time two-phase short circuit current. Relay protection device is installed with possibility of recording phase currents and voltages of each connection and backup cell of distributing device, as well as with possibility of fixation of single-phase short circuits to ground in each connection of distribution device, determination of location and calculation of distance to single-phase ground fault, taking into account complex load impedance and phase voltages, determining the location and calculating distance l to the single-phase ground fault location on the real part of the complex expression l = Re [{(I_dp + I_b – I_pb)⋅(z_p⋅L – z_m⋅L + z_l) –U_dp + U_pb}/{I_b⋅(z_p – z_m)}], where I_dp and U_dp – respectively, current and voltage of damaged phase, on which single-phase ground fault occurred; I_b is current flowing through ballast resistance; I_pb and U_pb – respectively current and voltage of phase closed by ballast resistance; z_p and z_m is the proper and mutual specific resistances of the damaged line; z_l – equivalent resistance of load phase, L – length of power transmission line with single-phase ground fault.

EFFECT: high accuracy of determining distance to the point of earth fault.

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