These signals shall be used for communication based earth-fault teleprotectioncommunication schemes (permissive or blocking).Simplified logic diagram for directional supervision element with integrateddirectional comparison step is shown in figure 97:Xaa>bbI>DirpolMethod=VoltagepolMethod=DualORFORWARD_IntREVERSE_IntBLOCKSTAGE1_DIR_Int0.6X0.4ANDSTAGE3_DIR_IntSTAGE4_DIR_IntSTAGE2_DIR_Int ORSTRVUPolMinIPolMinAngleRCATF0.0X TFRNPolXNPol 0.0DirectionalCharacteristicFWDRVS ANDANDAND STFWFORWARD_IntREVERSE_IntANDIEC07000067-5-en.vsd| |UPolUIPolIPolI3PDIRUTotPolIopDirComplexNumberaa>bbTF0.0polMethod=Current ORIEC07000067 V5 ENFigure 97: Simplified logic diagram for directional supervision element with integrated directional comparisonstep8.2.8 Second harmonic blocking elementA harmonic restrain of the Four step residual overcurrent protection functionEF4PTOC can be chosen. If the ratio of the 2nd harmonic component in relation to thefundamental frequency component in the residual current exceeds the pre-set leveldefined by parameter setting 2ndHarmStab. Any of the four residual overcurrentstages can be selectively blocked by parameter setting HarmRestrainx. When 2ndharmonic restraint feature is active the EF4PTOC function output signal2NDHARMD will be set to logical value one.1MRK 502 048-UEN A Section 8Current protection201Technical manual
