12.5.2 FunctionalityTo achieve fast fault clearance of ground faults on the part of the line not covered by theinstantaneous step of the residual overcurrent protection, the directional residualovercurrent protection can be supported with a logic that uses communication channels.In the directional scheme, information of the fault current direction must be transmitted tothe other line end. With directional comparison, a short operate time of the protectionincluding a channel transmission time, can be achieved. This short operate time enablesrapid autoreclosing function after the fault clearance.The communication logic module for directional residual current protection enablesblocking as well as permissive under/overreaching, and unblocking schemes. The logiccan also be supported by additional logic for weak-end infeed and current reversal,included in Current reversal and weak-end infeed logic for residual overcurrent protectionECRWPSCH (85) function.12.5.3 Function blockANSI09000009-1-en.vsdECPSCH (85)BLOCKBLKTRBLKCSCS_STOPPLTR_CRDCSORCSURCRCR_GUARDTRIPCSCRLLCGANSI09000009 V1 ENFigure 245: ECPSCH (85) function block12.5.4 SignalsTable 352:ECPSCH (85) Input signalsName Type Default DescriptionBLOCK BOOLEAN 0 Block of functionBLKTR BOOLEAN 0 Block pilot (communication assisted) tripBLKCS BOOLEAN 0 Block pilot channel startCS_STOP BOOLEAN 0 Block of channel start (CS) due to reverse fault detectionPLTR_CRD BOOLEAN 0 Signal to be used for coordinating local pilot tripping withthe channel receive (CR) signalCSOR BOOLEAN 0 Signal to be used for channel start with overreachingpilot schemesTable continues on next page1MRK 506 335-UUS A Section 12Scheme communication517Technical manual
