| 摘要 |
The invention concerns a security method designed to trigger an emergency protection system in case of failure in a differential protection system (2) following occurrence of an electric fault (7) in the line. Said method consists in measuring at least two independent physical quantities (G1, G2, Gn) with measuring systems (10) independent of the differential protection system (2), the measurements of each quantity being analyzed to produce a signal (11') which constitutes an assumption index of the presence or the absence of a fault in the line. If at least two assumption indices of the presence of a fault match, a triggering initializing signal (12') enables a unit triggering (14) emergency protection to await a possible validation signal (13) which will be generated if the fault has not been eliminated by the differential protection system after a predetermined delay has elapsed. Said validation signal closes at least a fast disconnecting link earthing device (16) provided in the line.
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