GE D90 Plus - Permissive Echo Signaling

664 D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
SINGLE-POLE TRIPPING CHAPTER 15: THEORY OF OPERATION
Permissive echo signaling
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
echoes 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 echoes 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
0 0 0 1 0 0 0 0 BG AG, AB, ABG, CA,
CAG, 3P,
unrecognized
DCUB TRIP B
11000000AG BG DCUB TRIP B
01000000AG BG DCUB TRIP B
00001100CG BG DCUB TRIP B
00000100CG BG DCUB TRIP B
00000011MULTI-P BG DCUB TRIP B
00000001MULTI-P BG DCUB TRIP B
0 0 0 0 1 1 0 0 CG CG, BC, BCG, CA,
CAG, 3P,
unrecognized
DCUB TRIP C
0 0 0 0 0 1 0 0 CG CG, BC, BCG, CA,
CAG, 3P,
unrecognized
DCUB TRIP C
11000000AG CG DCUB TRIP C
01000000AG CG DCUB TRIP C
00110000BG CG DCUB TRIP C
00010000BG CG DCUB TRIP C
00000011MULTI-P CG DCUB TRIP C
00000001MULTI-P CG DCUB TRIP C
11000000AG BC, BCG DCUB TRIP 3P
01000000AG BC, BCG DCUB TRIP 3P
0 0 1 1 0 0 0 0 BG CA, CAG DCUB TRIP 3P
0 0 0 1 0 0 0 0 BG CA, CAG DCUB TRIP 3P
00001100CG AB, ABG DCUB TRIP 3P
00000100CG AB, ABG DCUB TRIP 3P
00000011MULTI-P 3P or unrecognizedDCUB TRIP 3P
00000001MULTI-P 3P or unrecognizedDCUB TRIP 3P
Remote data Local data
Bit pattern Remote
determination of
fault type
Local
determination of
fault type
Trip output
RX
1
LO
G1
RX
2
LO
G2
RX
3
LO
G3
RX
4
LO
G4