SELECTIVE PROTECTION DEVICE AGAINST SINGLE-PHASE EARTH FAULT OF ELECTRIC NETWORKS OF MIDDLE VOLTAGE CLASS Russian patent published in 2022 - IPC H02H3/16 G01R31/08 

FIELD: electric power industry.

SUBSTANCE: invention relates to the electric power industry and can be used in electrical networks of medium voltage 6-35 kV, operating with an isolated or resistive-grounded neutral, in the event of stable single-phase ground faults (SSPGF), short-term single-phase ground faults (STSPGF), single-phase arc ground faults (SPAGF), arc intermittent single-phase ground faults (AISPGF). The effect is achieved by the fact that the device is additionally equipped with an insulation breakdown counter information “eraser” block, the input of which is connected to the output of the block of the first “AND” element, and the output is connected to the first erasing input of the insulation breakdown counter block. The output of the block of the counter of the number of insulation breakdowns is connected to the first input of the block for determining "dangerous" STSPGF, and the second input is connected to the setting for the number of dangerous STSPGF. The output of the "dangerous" STSPGF detection unit is connected to the STSPGF tripping output relay. The device allows you to implement protection against short-term, arc, arc intermittent and stable single-phase earth faults.

EFFECT: increasing the selectivity and stability of the functioning of the protection of medium voltage electrical networks 6-35 kV.

1 cl, 1 dwg