GE D60 Instruction Manual page 476

5.7 CONTROL ELEMENTS
This menu allows selecting and setting up protection signaling of the directional comparison unblocking scheme. This
scheme is available for single-pole tripping applications and can be used with one, two, or four bit communications chan-
nels. Choices of communications channel include remote inputs/outputs and telecommunications interfaces.
Generally, this scheme uses an over-reaching zone 2 distance element to compare the direction to a fault at all terminals of
the line. Ground directional overcurrent functions available in the relay can be used in conjunction with the zone 2 distance
element to key the scheme and initiate its operation. This increases the coverage for high-resistance faults.
The scheme is intended for two or three-terminal applications. As a long reach of the overreaching distance element may
be required for three-terminal applications, transient blocking logic is provided for both distance and ground directional
overcurrent elements. An echo feature is made available to cope with line open conditions.
5
By default the scheme uses the reverse-looking zone 4 distance element to identify reverse faults. Additionally, reverse-
looking ground directional overcurrent functions can be used in conjunction with the zone 4.
For proper operation of the scheme the zone 2 and 4 phase and ground distance elements must be enabled, configured
and set per rules of distance relaying. The line pickup element should be enabled, configured and set properly to detect
line-end-open conditions. If used by this scheme, the selected ground directional overcurrent function(s) must be enabled,
configured and set accordingly.
In single-pole tripping applications, the scheme uses local fault type identification provided by the phase selector together
with information received from the remote terminal. The scheme generates output operands (
that are used to transmit the signal to the remote terminal(s). The directional comparison unblocking scheme was devel-
oped for use with frequency shift keying communications channels, though different telecommunications interfaces can be
used (for example, digital communication channels utilizing the D60 teleprotection input/outputs).
To make the scheme fully operational as a stand-alone feature, the scheme output operands must be configured to inter-
face with other relay functions, output contacts in particular. Typically, the output operands should be programmed to initiate
a trip, breaker fail, and autoreclose, and drive a user-programmable LED as per the intended application.
When used in conjunction with the trip output element, the scheme is pre-configured to initiate trip, breaker fail and autore-
close actions.
• DCUB BLOCK: This setting allows the user to assign any FlexLogic operand to block the scheme. Contact inputs from
a pilot cut-out switch are typically used for this purpose.
• DCUB PERMISSIVE ECHO: Enabling this setting will send a permissive echo signal to the remote end(s) under cer-
tain conditions (see the logic diagram for details). If set to "Custom", the echo signal is sent if a condition selected with
the
DCUB ECHO COND
specified by the
ECHO LOCKOUT
ting. The echo is returned only if no overreaching and reverse protection elements operate.
• DCUB ECHO COND: This setting specifies a user-selected echo condition and applies only if the
setting is "Custom".
ECHO
• GND DIR O/C FWD: 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(s) and initiating
operation of the scheme (both through the transient blocking logic).
5-342
DCUB RX3:
MESSAGE
Off
DCUB LOG3:
MESSAGE
Off
DCUB RX4:
MESSAGE
Off
DCUB LOG4:
MESSAGE
Off
DCUB SCHEME TARGET:
MESSAGE
Self-Reset
DCUB SCHEME EVENTS:
MESSAGE
Disabled
setting is satisfied. The echo is sent only once and then the echo logic locks out for the time
setting. The duration of the echo pulse is programmable by the
D60 Line Distance Protection System
Range: FlexLogic operand
Range: FlexLogic operand
Range: FlexLogic operand
Range: FlexLogic operand
Range: Self-Reset, Latched, Disabled
Range: Disabled, Enabled
DCUB TX1
ECHO DURATION
5 SETTINGS
through )
DCUB TX4
set-
DCUB PERMISSIVE
GE Multilin