the possibility to detect high fault resistances, especially for phase-to-earth faults atthe remote line end. For example, for a given setting of the load angle ArgLd, theresistive blinder for the zone measurement can be set according to figure 53affording higher fault resistance coverage without risk for unwanted operation dueto load encroachment. Separate resistive blinder settings are available in forwardand reverse direction.The use of the load encroachment feature is essential for long heavily loaded lines,where there might be a conflict between the necessary emergency load transfer andnecessary sensitivity of the distance protection. The function can also preferably beused on heavy loaded, medium long lines. For short lines, the major concern is toget sufficient fault resistance coverage. Load encroachment is not a majorproblem. .RZ1ArgLdRLdFwIEC09000248-3-en.vsdxXRLdRv[1]IEC09000248 V3 EN-USFigure 53: Load encroachment phenomena and shaped load encroachmentcharacteristic[1]7.1.7.9 Simplified logic schemes GUID-B43F2F0B-C8A2-4CFD-A9DD-51E167A90B56 v5PHSL1, PHSL2,...PHSL3L1 are internal binary logical signals from the Phase-selection element. They correspond directly to the six loops of the distance zonesand determine which loops should be released to operate.FWL1, FWL2,...FWL3L1 and RVL1, RVL2,...RVL3L1 are the internal binarysignals from the Directional element. An FW signal is activated if the criteria for aforward fault or load is fulfilled for its particular loop. The equivalent applies to thereverse (RV) signals.The internal input 'IN present' is activated if the residual current (3I0) exceeds 10%of the maximum phase current magnitude and at the same time is above 5% of[1] RLdRv=RLdRvFactor*RLdFw1MRK 505 394-UEN A Section 7Impedance protectionLine differential protection RED650 2.2 IEC 133Technical manual
