GE D90 Plus Instruction Manual page 313

CHAPTER 7: PROTECTION
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
Echo Duration
Range: 0.000 to 65.535 seconds in steps of 0.001
Default: 0.100 seconds
This setting specifies the guaranteed and exact duration of the echo pulse. The duration
is not dependent on the duration and shape of received RX signals. This setting enables
the relay to avoid a permanent lock-up of the transmit-receive loop.
Echo Lockout
Range: 0.000 to 65.535 seconds in steps of 0.001
Default: 0.250 seconds
This setting specifies the lockout period for the echo logic after sending the echo pulse.
This enables the relay to avoid oscillations of the echo pulses during an autoreclosure
dead-time after clearing an internal fault.
Seal-In Delay
Range: 0.000 to 65.535 seconds in steps of 0.001
Default: 0.000 seconds
The FlexLogic operand is produced according to the hybrid POTT scheme
HYB POTT OP
logic. This setting specifies a minimum guaranteed duration for the
this operand runs the trip table of the hybrid POTT scheme, the
C, and
TRIP B, HYB POTT TRIP
period of time.
Ground Directional OC Forward
Range: any FlexLogic operand
Default: OFF
This setting defines 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 keying the
communication channel and initiating operation of the scheme (both through the
transient blocking logic). 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 for this setting, enabling the user to combine
responses of various protection elements or 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,
NEG SEQ DIR OC1 FWD
Coordinate the selected protection element (or elements in combination) with the
selection of the
Ground Directional OC Reverse
seen by an element selected by the
line, the reverse-looking element at the other end selected by
picks up and provides a blocking signal.
Reverse
Ground Directional OC Reverse
Range: any FlexLogic operand
Default: OFF
This setting defines the FlexLogic operand (if any) of a protection element used in
addition to zone 4 for identifying reverse faults, and thus, for stopping the transmit
signal and initiating the transient blocking timer. Good directional integrity is the key
requirement for a reverse-looking protection element used for this feature.
Even though any operand can be used for this setting, 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
trip operands are sealed-in for the same
HYB POTT TRIP 3P
or
NEUTRAL DIR OC1
setting. For all the forward external faults
Ground Directional OC Forward
CONTROL ELEMENTS
pulse. As
HYB POTT OP
HYB POTT TRIP A, HYB POTT
FWD).
at one end of the
Ground Directional OC
303