GE D90 Plus Instruction Manual page 269

CHAPTER 7: PROTECTION
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
either the negative sequence directional or neutral directional overcurrent element. Both
these elements have separate forward and reverse output operands. The reverse
indication should be used (that is,
The selected protection element (or elements in combination) should be coordinated
with the selection of the
external faults seen by an element selected by the
setting at one end of the line, the reverse-looking element at the other selected by the
Ground Directional OC Forward
Communication Bits
Range: 1, 2, 4
Default: 1
This setting specifies the number of bits of the communications channel available for the
scheme. With only one bit available, the scheme sends the hybrid permissive over-
reaching transfer trip command on bit 1 (the
direct trip command received on bit 1 (the
type identification provided by the phase selector to assert the trip operands
TRIP A, HYB POTT TRIP B, HYB POTT TRIP
RX1, RX2, RX3, RX4
Range: any FlexLogic™ operand
Default: OFF
These settings allow the user to select the FlexLogic™ operands that represent the
receive signals for the scheme. Typically input contacts interfacing with a signaling
system are used as follows.
– In single-bit applications,
– In two-bit applications,
– In four-bit applications,
Events
Range: Enabled, Disabled
Default: Enabled
This setting enables and disables the logging of hybrid permissive over-reaching transfer
trip (hybrid POTT) scheme events in the sequence of events recorder.
Echo Condition
Range: any FlexLogic™ operand
Default: OFF
This setting specifies an and applies an echo condition when the
is "Custom".
Weak Infeed
Range: Enabled, Custom, Disabled
Default: Disabled
If this setting is "Enabled", the scheme activates both the keying and operating paths
using a pre-programmed weak infeed logic (refer to the logic diagram below). If this
setting is "Custom", the weak infeed condition is to be specified by the user via the
setting.
Infeed Condition
Weak Infeed Condition
Range: any FlexLogic™ operand
Default: OFF
This setting specifies and applies a weak infeed condition when the
is "Custom".
NEG SEQ DIR OC1 REV
Ground Directional OC Forward
setting end should pickup and provide a blocking signal.
HYB POTT TX1
setting). The scheme uses only local fault
RX1
C, and
HYB POTT TRIP
must be used.
RX1
and must be used.
RX1 RX2
through must be used.
RX1 RX4
CONTROL ELEMENTS
or
NEUTRAL DIR OC1 REV).
setting. For all the forward
Ground Directional OC Forward
operand) and responds to the
3P).
Permissive Echo
Weak Infeed
(HYB POTT
setting
Weak
setting
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