GE D90 Plus Instruction Manual page 271

CHAPTER 7: PROTECTION
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
distance element to increase the coverage for high resistance faults. Also by default, only a
reverse-looking zone 4 distance element identifies reverse faults. The ground directional
overcurrent functions can be used in conjunction with the zone 4 distance element for
better time and sensitivity coordination.
For proper operation, the zone 2 and 4 phase and ground distance elements must be
enabled and configured according to the principles of distance relaying. If used by the
directional comparison blocking scheme, the selected ground directional overcurrent
functions must be enabled and configured accordingly.
In single-pole tripping applications, the directional comparison blocking scheme uses local
fault type identification provided by the phase selector together with information received
from the remote terminal.
The directional comparison blocking scheme generates output operands
and through
DIR BLOCK TX1 STOP
to the remote ends. When used with telecommunications facilities the output operands
should be assigned to operate output contacts connected to key the transmitter at the
interface.
The
DIR BLOCK A, DIR BLOCK
configured to interface with other relay functions, in particular the output contacts, to
make the scheme fully operational. The output operand is typically programmed to initiate
a trip, breaker fail, and autoreclose, and drive an annunciator indication as per user
requirements.
When used in conjunction with the trip output element, the directional comparison
blocking scheme is pre-configured to initiate trip, breaker fail, and single-pole autoreclose
actions.
Select the Settings > Protection > Control > Pilot Schemes > Blocking Scheme menu item
to access the directional comparison blocking scheme settings.
Figure 208: Directional comparison blocking configuration settings
The following settings are available for the directional comparison blocking scheme.
Function
Range: Enabled, Disabled
Default: Disabled
This setting enables and disables the directional comparison blocking scheme.
STOP) that control the transmission of signals
DIR BLOCK TX4
C, and
B, DIR BLOCK DIR BLOCK 3P
CONTROL ELEMENTS
(DIR BLOCK TX INIT
output operands must be
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