Permissive Echo Signaling - GE D90 Plus Instruction Manual

CHAPTER 15: THEORY OF OPERATION

Permissive echo signaling

PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
Remote data
Bit pattern
RX LO RX LO RX LO
1 G1 2 G2 3 G3
0 0 0 1 0 0
1 1 0 0 0 0
0 1 0 0 0 0
0 0 0 0 1 1
0 0 0 0 0 1
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 1 1
0 0 0 0 0 1
1 1 0 0 0 0
0 1 0 0 0 0
0 0 1 1 0 0
0 0 0 1 0 0
0 0 0 0 0 0
0 0 0 0 0 0
1 1 0 0 0 0
0 1 0 0 0 0
0 0 1 1 0 0
0 0 0 1 0 0
0 0 0 0 1 1
0 0 0 0 0 1
0 0 0 0 0 0
0 0 0 0 0 0
The echo feature can reduce the response time of an over-reaching scheme when a
terminal is disconnected from the line. In this condition, a zone 2 element at the terminal
that remains in-service can detect a fault, but cannot trip, as a permissive signal is not
received from the remote terminal. This feature is provided in the permissive over-reaching
transfer trip and hybrid permissive over-reaching transfer trip schemes.
When used with the permissive overreaching transfer trip (POTT) scheme, this feature will
echo a reliable received permissive signal back to the originating terminal when a 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 user-
specified period. The duration of the echo pulse does not depend on the duration or shape
of the received RX signals but is user-programmable. The echo is sent back only if none of
the overreaching protection elements operates.
When used with the hybrid permissive overreaching transfer trip (hybrid POTT) scheme,
this feature will echo a reliable received permissive signal back to the originating terminal
if the line-end open condition is recognized by the line pickup scheme and the fault is not
identified as a reverse fault by the zone 4 or the ground directional overcurrent function (if
Remote
determination of
RX LO
fault type
4 G4
0 0 BG
0 0 AG
0 0 AG
0 0 CG
0 0 CG
1 1 MULTI-P
0 1 MULTI-P
0 0 CG
0 0 CG
0 0 AG
0 0 AG
0 0 BG
0 0 BG
1 1 MULTI-P
0 1 MULTI-P
0 0 AG
0 0 AG
0 0 BG
0 0 BG
0 0 CG
0 0 CG
1 1 MULTI-P
0 1 MULTI-P
SINGLE-POLE TRIPPING
Local data
Local Trip output
determination of
fault type
AG, AB, ABG, CA, DCUB TRIP B
CAG, 3P,
unrecognized
BG DCUB TRIP B
BG DCUB TRIP B
BG DCUB TRIP B
BG DCUB TRIP B
BG DCUB TRIP B
BG DCUB TRIP B
CG, BC, BCG, CA, DCUB TRIP C
CAG, 3P,
unrecognized
CG, BC, BCG, CA, DCUB TRIP C
CAG, 3P,
unrecognized
CG DCUB TRIP C
CG DCUB TRIP C
CG DCUB TRIP C
CG DCUB TRIP C
CG DCUB TRIP C
CG DCUB TRIP C
BC, BCG DCUB TRIP 3P
BC, BCG DCUB TRIP 3P
CA, CAG DCUB TRIP 3P
CA, CAG DCUB TRIP 3P
AB, ABG DCUB TRIP 3P
AB, ABG DCUB TRIP 3P
3P or unrecognized DCUB TRIP 3P
3P or unrecognized DCUB TRIP 3P
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