ADAPTIVE PROTECTION DEVICE FROM SINGLE PHASE-TO-EARTH FAULTS IN NETWORKS WITH ISOLATED NEUTRAL AND WITH CAPACITY CURRENTS COMPENSATION Russian patent published in 2017 - IPC H02H3/16 

FIELD: electricity.

SUBSTANCE: on each line the device contains the zero sequence current sensor, the zero-sequence voltage measuring transformer, the current measuring relay transformer with the set minimum operating value, the automatic adaptive current correction module of the minimum operating value, the output of which is connected to the second input of the current measuring relay transformer with the set minimum operating value, the first, the second, the third and the fourth band-pass frequency filters, the first and the second switching units, the differentiator, the first and the second root-mean-square value (RMS) calculation units, the time delay element.

EFFECT: sensitivity increase and expansion of the application field of the current zero sequence protection with two supplied values at stable and arc intermittent earth faults in medium voltage electrical circuits, operating with isolated neutral or capacitive currents compensation to earth fault.

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