ABB Relion 620 Series - Page 80

3.2.3.2 Other critical feeders
The examples given for motor feeders can be applied for other types of feeders as
well. The following examples are for critical feeders in which the protection system
dependability, security or both are the drivers.
TC
-Q0
-A1
Control +
+J01 +J0x
Control -
SOTO
-F1
TC
R1
Control +
Control -
-A1
-A1
IRF
-TO
-R1
-F1
Incomer
protec
on start +
Incomer
protec
on start +
Incomer
protec
on start -
Incomer
protec on start -
-Q0
AUX. POWER
AUX. POWER
Figure 17: Redundant protection fail-safe principle, example 1
J01 Incomer feeder panel
J0x Load feeder panels
Q0 Circuit breaker (CB)
TO Relay trip output
SO Relay start output
A1 Protection relay
R1 Auxiliary relay
TC CB trip coil
F1 Miniature circuit breaker
In example 1, the fail-safe approach aims at securing circuit breaker tripping even
if a relay fails. The incomer panel relay indicates the start of selected protection
functions. This start signal is distributed to all load feeder panels. If a relay in the
load feeder panel indicates an IRF status, the start signal of the incomer panel
relay results in circuit breaker tripping. This approach offers basic protection for a
load feeder while the actual protection relay performs a self-supervision controlled
restart sequence.
Basic functions
1MRS757644 H
80 620 series
Technical Manual