2 Functions
392
7SD5 Manual
C53000-G1176-C169-1
2.22.2.1 Functional Description
Supervision with
Two Binary Inputs
When using two binary inputs, these are connected according to Figure 2-168, parallel
to the associated trip contact on one side, and parallel to the circuit breaker auxiliary
contacts on the other.
A precondition for the use of the trip circuit supervision is that the control voltage for
the circuit breaker is higher than the total of the minimum voltages drops at the two
binary inputs (U
Ctrl
> 2·U
BImin
). Since at least 19 V are needed for each binary input,
the supervision function can only be used with a system control voltage of over 38 V.
Figure 2-168 Principle of the trip circuit supervision with two binary inputs
Supervision with binary inputs not only detects interruptions in the trip circuit and loss
of control voltage, it also supervises the response of the circuit breaker using the po-
sition of the circuit breaker auxiliary contacts.
Depending on the conditions of the trip contact and the circuit breaker, the binary
inputs are activated (logical condition „H“ in the following table), or short-circuited (log-
ical condition „L“).
A state in which both binary inputs are not activated („L“) is only possible in intact trip
circuits for a short transition period (trip relay contact closed but circuit breaker not yet
open).
A continuous state of this condition is only possible when the trip circuit has been in-
terrupted, a short-circuit exists in the trip circuit, a loss of battery voltage occurs, or
malfunctions occur with the circuit breaker mechanism. Therefore, it is used as moni-
toring criterion.
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