ABB RELION REX640, Техническое руководство, Страница: 115 / 1960

J01 Feeder #1 panel
J02 Feeder #2 panel
Q0 Circuit breaker (CB)
TO1 Relay trip output #1
TO2 Relay trip output #2
A1
Protection relay
TC1 CB trip coil 1
TC2 CB trip coil 2
F1 Miniature circuit breaker
In example 2, the fail-safe approach aims at securing circuit breaker tripping even
if a relay fails. A relay in a panel measures also the adjacent panel’s currents (and
voltages) and receives the necessary primary device’s position information. In other
words, the relay in a panel functions as a backup relay for the adjacent panel.
This approach allows service continuation while the failed relay is waiting for spare
parts or a complete replacement. The backup protection features provided by the
adjacent panel’s relay do not necessarily fully match the features available in the
main relay.
TC1 TC2
C
Control -
-A2 -A1
TO
-F1
-Q0
TO
AUX. POWER AUX. POWER
Figure 37: Redundant protection fail-safe principle, example 3
Q0 Circuit breaker (CB)
A1 Protection relay #1
A2 Protection relay #2
TO Protection relay trip output
TC1 CB trip coil 1
TC2 CB trip coil 2
F1 Miniature circuit breaker
In example 3, the fail-safe approach aims at securing circuit breaker tripping even if
one of the redundant relays fails. The scheme is often referred to as the 1-outof- 2
approach. This approach allows service continuation while the failed relay is waiting
for spare parts or a complete replacement. The redundancy in this example covers
relays and circuit breaker tripping coils but it can be expanded to auxiliary power
supplies (two station batteries and isolated distribution), cabling, circuit breaker
failure protection, and so on. Another variant of this approach is to have a main relay
and a backup relay instead of two fully redundant relays. The backup relay does not
1MRS759142 F Basic functions
REX640
Technical Manual
115