CHAPTER 5: SETTINGS CONTROL ELEMENTSL90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL 5-3635The 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 protectionelements, or to apply extra security conditions through FlexLogic equations, this signal is primarily meant to be the outputoperand from either the Negative-Sequence Directional IOC or Neutral Directional IOC. Both of these elements haveseparate forward (FWD) and reverse (REV) output operands. The forward indication is used (NEG SEQ DIR OC1 FWD orNEUTRAL DIR OC1 FWD).Figure 5-207: POTT1 (ground) scheme logic5.8.12.6 Hybrid permissive over-reaching transfer tripSETTINGS CONTROL ELEMENTS PILOT SCHEMES HYBRID POTT SCHEME HYBRID POTT SCHEME HYB POTT SCHEMEFUNCTION: DisabledRange: Disabled, Enabled HYB POTT BLOCK:OffRange: FlexLogic operand HYB POTT PERMISSIVEECHO: DisabledRange: Disabled, Enabled, Custom HYB POTT ECHO COND:OffRange: FlexLogic operand
