ABB RELION REX640 Technical Manual page 111

1MRS759142 F
-F1
Figure 31: Motor feeder fail-safe trip circuit principle, example 1
A1
ES
Q0
TO
IRF
<U
TC1
DCS
F1
In example 1, the fail-safe approach aims at securing motor shutdown via an
emergency switch and in case the control voltage disappears. In case of a
temporary internal relay fault, the circuit breaker is immediately tripped before the
relay recovers from the situation. In case the IRF output relay is directly connected
to the undervoltage trip coil circuit, the output's performance figures (make and
break values) must be checked.
-F1
Figure 32: Motor feeder fail-safe trip circuit principle, example 2
A1
ES
Q0
Table continues on the next page
REX640
Technical Manual
Control +
ES
-A1
IRF
-Q0
<U
Control -
Protection relay
Emergency stop
Circuit breaker (CB)
Protection relay trip output
Internal relay fault indication
CB undervoltage trip coil
CB trip coil 1
Distributed process control system
Miniature circuit breaker
Control +
-A1
ES
TO
-Q0
<U
TC1
Control -
Protection relay
Emergency stop
Circuit breaker (CB)
TO
AUX. POWER
TC1
AUX. POWER
IRF
DCS
Basic functions
111