Directional detection of a sensitive medium-voltage earth fault by linear correlation

摘要

The device (10) has a storage unit (20) to store values of signals representative of homopolar current (I0) and phases (DELTAI0) during a storage period prior to a detection signal (D) of occurrence of earth fault. A signal processing unit (30) has a determination unit to determine a variation of the signal representative of the current and of each of the phases relative to the values. A calculation unit (34) calculates standardized correlation coefficients (rA-rC) between the variations of the signal representative of the current and of signals representative of phase currents (IA-IC). Independent claims are also included for the following: (1) an earth fault passage indicator (2) a protection relay for earth (3) a method for directional detection of an earth fault in a multiphase network (4) a method for protecting a current line during occurrence of an earth fault.