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5 SETTINGS
The POTT1 pilot scheme operates the same way as the regular POTT scheme, except hard-coded connections to phase
and 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 communication
channel and initiating operation of the scheme. Good directional integrity is the key requirement for an over-reaching
forward-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 be
the 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 SEQ
DIR OC1 FWD or NEUTRAL DIR OC1 FWD).
GE Multilin
Figure 5–164: POTT1 (GROUND) SCHEME LOGIC
L90 Line Current Differential System
5.7 CONTROL ELEMENTS
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