GE D90 Plus Instruction Manual page 318

CONTROL ELEMENTS
308
Ground Directional OC Forward
Range: any FlexLogic operand
Default: OFF
This setting selects the FlexLogic operand (if any) of a protection element used in
addition to zone 2 for identifying faults on the protected line, and thus, for initiating
operation of the scheme. Good directional integrity is the key requirement for an over-
reaching forward-looking protection element used for this feature.
Even though any operand can be used, enabling the user to combine responses of
various protection elements or to apply extra conditions through FlexLogic equations,
this extra signal is primarily meant to be the output operand from either the negative-
sequence directional or neutral directional overcurrent elements. Both these elements
have separate forward and reverse output operands.
Use the forward indication (that is,
Coordinate the selected protection element (or elements in combination) with this
setting. For all the forward external faults seen by an element selected by the
setting at one end of the line, the reverse-looking element
Directional OC Forward
selected by the Ground Directional OC Reverse
provides a blocking signal.
Ground Directional OC Reverse
Range: any FlexLogic operand
Default: OFF
This setting selects the FlexLogic operand (if any) of a protection element that is used in
addition to zone 4 for identifying reverse faults, and thus, for initiating the blocking
signal. Either reverse-looking directional or non-directional overcurrent protection
element can be used for this feature.
Even though any operand can be used, enabling the user to combine responses of
various protection elements or to apply extra conditions through FlexLogic equations,
this extra signal is meant to be the output operand from either the negative-sequence
directional, neutral directional, or a non-directional instantaneous overcurrent element.
Coordinate the selected protection element (or elements in combination) with the
selection of the
Ground Directional OC Forward
seen by an element selected by the
the line, the reverse-looking element selected by the
setting at the other end picks up and provides a blocking signal.
Communication Bits
Range: 1, 2, 4
Default: 1
This setting specifies the number of bits of the communications channel available for the
directional comparison blocking scheme. With only one bit available, the scheme sends
the blocking signal by asserting the
the channel (set the blocking signal). On internal faults, the scheme removes the blocking
signal by asserting the
DIR BLOCK TX1
For tripping, the directional comparison blocking scheme responds to lack of the
blocking signal on bit 1 (selected by the
type identification provided by the phase selector to assert the
BLOCK TRIP B, DIR BLOCK TRIP
To take advantage of the four-bit blocking scheme, initiate the blocking signals from a
disturbance detector. This can be accomplished by using both 50DD and the
operand to assert the blocking signal. Subsequently, specific bits are de-asserted
TX INIT
by the scheme based on the phase selection providing the peer device with more
information on the fault type. Otherwise, the peer device issues a three-pole trip upon
receiving the [0, 0, 0, 0] bit pattern.
NEG SEQ DIR OC1 FWD
setting at the other end picks up and
setting. For all the forward external faults
Ground Directional OC Forward
operand. Use this operand to start
DIR BLOCK TX INIT
FlexLogic operand.
setting). The scheme uses only local fault
RX1
C, and output operands.
DIR BLOCK TRIP 3P
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 7: PROTECTION
or
NEUTRAL DIR OC1 FWD).
Ground
setting at one end of
Ground Directional OC Reverse
DIR BLOCK TRIP A,
DIR BLOCK
DIR