short transition periods. After clearance of the failure in the trip circuit, the failure alarm automatically resets
with the same time delay.
[logikdiagramm-auskruebrwchg-2-be-wlk-310702, 1, en_GB]
Figure 2-60 Logic diagram of the trip circuit supervision with two binary inputs
Supervision with One Binary Input
According to Figure 2-61, the binary input is connected in parallel to the respective command relay contact of
the protection device. The circuit breaker auxiliary contact is bridged with a high-resistance bypass resistor R.
The control voltage for the circuit breaker should be at least twice as high as the minimum voltage drop at the
binary input (U
Ctrl
> 2·U
BImin
). Since at least 19 V are needed for the binary input, the monitor can be used with
a system control voltage of over 38 V.
A calculation example for the bypass resistor R is shown in the configuration notes in Section “Mounting and
Connections”, margin heading “Trip Circuit Supervision”.
[prinzip-ausloesekrueb-1-be-wlk-010802, 1, en_GB]
Figure 2-61 Principle of the trip circuit supervision with one binary input
TR Trip relay contact
CB Circuit breaker
TC Circuit breaker trip coil
Aux1 Circuit breaker auxiliary contact (NO contact)
Aux2 Circuit breaker auxiliary contact (NC contact)
U-CTR Control voltage for trip circuit
U-BI Input voltage of binary input
R Bypass resistor
UR Voltage across the 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 bypass resistor R. Only as long as the trip contact is closed, the
binary input is short-circuited and thereby deactivated (logical condition “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.
Functions
2.7 Monitoring Functions
146 SIPROTEC 4, 7VK61, Manual
C53000-G1176-C159-5, Edition 05.2018
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