Pilot Schemes - GE UR Series Instruction Manual
Line differential relay
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Also See for UR Series:
- Instruction manual (652 pages) ,
- Manual (433 pages) ,
- Release notes (33 pages)
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5.6 CONTROL ELEMENTS
a) PERMISSIVE OVER-REACHING TRANSFER TRIP (POTT)
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PATH: SETTINGS
CONTROL ELEMENTS
„
POTT SCHEME
„
5
This scheme is intended for two-terminal line applications only. It uses an over-reaching Zone 2 distance element to essen-
tially compare the direction to a fault at both the ends 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 pro-
vides increased coverage for high-resistance faults.
For proper scheme operation, the Zone 2 phase and ground distance elements must be enabled, configured, and set per
the rules of distance relaying. The Line Pickup element should be enabled, configured and set properly to detect line-end-
open/weak-infeed conditions. If used by this scheme, the selected ground directional overcurrent function(s) must be
enabled, configured, and set accordingly.
POTT PERMISSIVE ECHO:
If set to "Enabled" this setting will result in sending a permissive echo signal to the remote end. The permissive signal is
echoed back upon receiving a reliable POTT RX signal from the remote end while the line-end-open condition is identified
by the Line Pickup logic. The Permissive Echo is programmed as a one-shot logic. The echo is sent only once and then the
echo logic locks out for a settable period of time (
on the duration or shape of the received POTT RX signal but is settable as
POTT RX PICKUP DELAY:
This setting enables the relay to cope with spurious receive signals. The delay should be set longer than the longest spuri-
ous TX signal that can occur simultaneously with the zone 2 pickup. The selected delay will increase the response time of
the scheme.
5-148
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PILOT SCHEMES
POTT SCHEME
FUNCTION: Disabled
POTT PERMISSIVE
MESSAGE
ECHO: Disabled
POTT RX PICKUP
MESSAGE
DELAY: 0.000 s
TRANS BLOCK PICKUP
MESSAGE
DELAY: 0.020 s
TRANS BLOCK RESET
MESSAGE
DELAY: 0.090 s
ECHO DURATION:
MESSAGE
0.100 s
ECHO LOCKOUT:
MESSAGE
0.250 s
LINE END OPEN PICKUP
MESSAGE
DELAY:
0.050 s
POTT SEAL-IN
MESSAGE
DELAY:
0.400 s
GND DIR O/C FWD:
MESSAGE
Off
POTT RX:
MESSAGE
Off
ECHO LOCKOUT
L90 Line Differential Relay
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POTT SCHEME
Range: Disabled, Enabled
Range: Disabled, Enabled
Range: 0.000 to 65.535 s in steps of 0.001
Range: 0.000 to 65.535 s in steps of 0.001
Range: 0.000 to 65.535 s in steps of 0.001
Range: 0.000 to 65.535 s in steps of 0.001
Range: 0.000 to 65.535 s in steps of 0.001
Range: 0.000 to 65.535 s in steps of 0.001
Range: 0.000 to 65.535 s in steps of 0.001
Range: FlexLogic™ operand
Range: FlexLogic™ operand
setting). The duration of the echo pulse does not depend
ECHO DURATION
5 SETTINGS
5.6.12 PILOT SCHEMES
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GE Power Management
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