METHOD OF DETERMINING THE POINT AND DISTANCE TO SINGLE-PHASE GROUND FAULT IN 6-35 KV ELECTRIC NETWORKS WITH ISOLATED OR COMPENSATED NEUTRAL 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. Ballast resistance is connected to backup cell of busbar section of distribution device, in which there is short circuit to earth, includes high-voltage switch of backup cell, providing leakage 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 distribution 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 point of single-phase earth fault; connecting the ballast resistance to the backup section of the busbar section of the distribution device, in which there is a ground fault; switching on the high-voltage breaker of the backup cell, providing two-phase short circuit current flowing through the ballast resistance of the short-circuited value and time; recording currents and voltages of all phases; determining the place and calculating the distance l to the place of single-phase earth fault along the real part of the complex expression

,

where I_f.p and U_f.p – respectively, current and voltage of faulted phase, on which single-phase ground fault occurred; I_u.p and U_u.p – respectively current and voltage of unfaulted phase; I_b – current flowing through ballast resistance; I_p.b and U_p.b – respectively, current and voltage of phase closed by ballast resistance; z_l and z_m – proper and mutual specific resistances of the damaged line.

EFFECT: high accuracy of determining distance to a single-phase ground fault.

1 cl, 2 dwg