METHOD OF DIAGNOSTICS AND DIRECTED PROTECTION AGAINST SINGLE-PHASE SHORT CIRCUITS IN ELECTRICAL NETWORKS Russian patent published in 2014 - IPC H02H3/16 

FIELD: electricity.

SUBSTANCE: instantaneous values of zero-sequence current and rate of rise in instantaneous values of zero-sequence voltage for transient process are measured at the moment of isolation phase-to-ground failure of the isolation. Integral quantity is calculated for the time interval of the protection actuation. The command is generated to executive elements of the protection when the integral quantity is exceeded for the preset value. Cross-correlation function is formed for the aggregate of instantaneous values of zero-sequence current and rate of rise in instantaneous values of zero-sequence voltage. At unstable single line-to-ground faults state of the isolation is diagnosed against a number of isolation failures fixed at integral quantity excess of the preset value. During the period of the protection actuation values are accumulated of the formed cross-correlation function for the aggregate of instantaneous values of zero-sequence current and rate of rise in instantaneous values of zero-sequence voltage, and the accumulated values of the cross-correlation function for the aggregate of instantaneous values of zero-sequence current and rate of rise in instantaneous values of zero-sequence voltage are selected as integral quantity.

EFFECT: improving stable functioning in conditions of interference and noise.

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