5-330 D60 Line Distance Protection System GE Multilin5.7 CONTROL ELEMENTS 5 SETTINGS5The POTT1 pilot scheme operates the same way as the regular POTT scheme, except hard-coded connections to phaseand ground distance elements are removed to allow the user to choose directional elements, for example ground OC direc-tional elements. This allows a user to apply the POTT1 scheme using solely directional elements to achieve better coordi-nation, rather than mixing up distance and ground OC directional elements together.The settings and application guidance for the POTT scheme applies to the POTT1 scheme. See the POTT section.• DIR FWD1..3: This setting defines the FlexLogic operand of a protection element used for keying the communicationchannel and initiating operation of the scheme. Good directional integrity is the key requirement for an over-reachingforward-looking protection element used as DIR FWD.Even though any FlexLogic operand can be used as DIR FWD allowing the user to combine responses of various pro-tection elements, or to apply extra security conditions through FlexLogic equations, this signal is primarily meant to bethe output operand from either the Negative-Sequence Directional IOC or Neutral Directional IOC. Both of these ele-ments have separate forward (FWD) and reverse (REV) output operands. The forward indication is used (NEG SEQDIR OC1 FWD or NEUTRAL DIR OC1 FWD).Figure 5–168: POTT1 (GROUND) SCHEME LOGICSETTINGSETTINGFLEXLOGIC OPERANDFLEXLOGIC OPERANDSETTINGSETTINGPOTT1 SCHEMEFUNCTION:EnabledCustomDIR FWD1:LINE PICKUP LEO PKPOffPOTT1 OPPOTT1 PERMISSIVE ECHO:POTT ECHO COND:Disabled = 0Off = 0Disabled837039A2.CDROff = 0SETTINGSSETTINGSSETTINGS SETTINGSSETTINGSPOTT1 RX PICKUPDELAY:TRANS BLOCK PICKUPDELAY:LINE END OPEN PICKUPDELAY:ECHO DURATION:TRANS BLOCK RESETDELAY:POTT1 SEAL-INDELAY:ANDANDANDANDANDOR0t RST0t RSTt PKPt PKPt PKP0ECHO LOCKOUT:Echo duration and lockout logicSETTINGSPOTT1 RX1:POTT1 RX2:POTT1 RX3:POTT1 RX4:POTT1 NO OF COMMBITS:Off = 0Off = 0Off = 0Off = 0ORFLEXLOGIC OPERANDSPOTT NO OF COMMBITS:POTT1 TX1POTT1 TX2POTT1 TX3POTT1 TX4ECHO TABLETRANSMIT TABLEPhaseSelectorRXRXRUNRUNFLEXLOGIC OPERANDSPOTT NO OF COMMBITS:POTT1 TRIP APOTT1 TRIP BPOTT1 TRIP CPOTT1 TRIP 3PTRIP TABLEPhaseSelectorRUNAND0100 msecSETTINGPOTT1 SCHEME BLOCK:OFF = 0ANDFLEXLOGIC OPERANDSAR FORCE 3P TRIPOPEN POLE OPFLEXLOGIC OPERANDSAR FORCE 3P TRIPOPEN POLE OPPhaseSelectorFLEXLOGIC OPERANDSAR FORCE 3P TRIPOPEN POLE OPDIR FWD2:Off = 0DIR FWD3:Off = 0
