Siemens SIPROTEC 7UT613 series Manual page 290

2 Functions
290
Figure 2-119 Logic diagram of the trip circuit supervision using one binary input
TR Trip relay contact
CB Circuit breaker
TC Circuit breaker trip coil
Aux1 Circuit breaker auxiliary contact (make)
Aux2 Circuit breaker auxiliary contact (break)
U Control voltage (trip voltage)
Ft
U Input voltage of binary input
BI
U Voltage across the substitute resistor
R
R Bypass resistor
During normal operation, the binary input is activated (logical condition „H") when the
trip contact is open and the trip circuit is intact, because the supervision circuit is
closed either by the circuit breaker auxiliary contact (if the circuit breaker is closed) or
through the equivalent resistor R. Only as long as the trip contact of the command
relay is closed, the binary input is short-circuited and thereby deactivated (logical con-
dition „L").
If the binary input is permanently deactivated during operation, an interruption in the
trip circuit or a failure of the (trip) control voltage can be assumed.
The trip circuit supervision does not operate during system faults. A momentary closed
tripping contact does not lead to a failure indication. If, however, the trip contacts of
other devices are connected in parallel, the alarm must be delayed.
When the fault in the trip circuit has been cleared, the annunciation is automatically
reset.
Figure 2-120 Logic Diagram of the Trip Circuit Supervision with One Binary Input (simplified)
7UT613/63x Manual
C53000-G1176-C160-2