ABB Relion 620 Series - Page 78

<U
TC1
-Q0
AUX. POWER
-A1
-F1
Control +
Control -
ES
IRF
DCS
TO
Figure 14: Motor feeder fail-safe trip circuit principle, example 2
A1 Protection relay
ES Emergency stop
Q0 Circuit breaker (CB)
TO Protection relay trip output
IRF Internal relay fault indication
<U CB undervoltage trip coil
TC1 CB trip coil 1
DCS Distributed process control system
F1 Miniature circuit breaker
In example 2, the fail-safe approach aims at securing motor shutdown via an
emergency switch and in case the control voltage disappears. In case of internal
relay fault, the necessary actions must be initiated by the process operators or by
the control system.
<U
TC1
-Q0
AUX. POWER
-A1
-F1
Control +
Control -
ES
IRF
-K1
-K1
TO
Figure 15: Motor feeder fail-safe trip circuit principle, example 3
A1 Protection relay
ES Emergency stop
Q0 Circuit breaker (CB)
TO Protection relay trip output
Table continues on the next page
Basic functions 1MRS757644 H
78 620 series
Technical Manual