Operation Of The Directional Comparison Unblocking Scheme - Ametek UPLC CU44-VER04 Applications Manual

UPLC™ Application Manual
Table 3–1. Operation of the Directional Comparison Unblocking Scheme.
SCHEME FOR EXTERNAL AND INTERNAL FAULTS
Type of Fault
External (F E )
Internal (F I )
Table 3–2. Operation of the Underreaching Transfer Trip Scheme.
SCHEME FOR EXTERNAL AND INTERNAL FAULTS
Type of Fault
External (F E )
Internal (F I )
(Fault near station H)
† Omitted in non-permissive systems.
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Events at Station G
P 1 operates.
f 1 channel shifts to unblock.
f 2 channel continues to
block.
No trip.
P 1 operates.
f 1 channel to unblock.
Loss of block and/ or receipt
of unblock (f 2 ) operates RR
or inputs AND.
Trip.
Events at Station G
P 1 does not operate.
No channel signal sent to H.
No trip.
P 1 does not operate.
No channel signal sent to H.
† (FD
1 operates).
Transfer-trip (f 2 ) from sta-
tion H operates RR or
inputs to AND (or OR if non-
permissive).
Trip.
Events at Station H
P 2 does not see fault.
Loss of block and/or receipt
of unblock (f 1 ) operates RR
or inputs AND.
No trip.
P 2 operates.
f 2 channel shifts to unblock.
Loss of block and/or receipt
of unblock (f 1 ) operates RR
or inputs AND.
Trip.
Events at Station H
P 2 does not operate.
No channel signal sent to G.
No trip.
P 2 operates and trips direct-
ly.
Transfer-trip signal keyed to
station G.
† (FD
2 operates).
Trip.