GE D90 Plus Instruction Manual page 314

CONTROL ELEMENTS
304
sequence directional or neutral directional overcurrent element. Both these elements
have separate forward and reverse output operands. Use the reverse indication
or
DIR OC1 REV NEUTRAL DIR OC1
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 at the other selected by the
setting end picks up and provide a blocking signal.
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 and applies an echo condition when the
"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 (see the logic diagram). If this setting is
"Custom," the weak infeed condition is to be specified by the user via the
setting.
Condition
Weak Infeed Condition
Range: any FlexLogic operand
Default: OFF
This setting specifies and applies a weak infeed condition when the
is "Custom."
The figure shows the hybrid POTT scheme logic.
REV).
setting. For all the forward external faults
Ground Directional OC Forward
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
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 7: PROTECTION
(NEG SEQ
setting at one end of
Ground Directional OC
operand) and responds to the
(HYB POTT
3P).
setting is
Permissive Echo
Weak Infeed
setting
Weak Infeed