2 Functions
176
7UM61 Manual
C53000-G1176-C127-3
2.29 Trip Circuit Supervision
The Multi-Functional Protective Relay 7UM61 is equipped with an integrated trip
circuit supervision. Depending on the number of available binary inputs (connected or
not to a common potential), monitoring with one or two binary inputs can be selected.
If allocation of the required binary inputs does not match the selected monitoring type,
then an indication to this effect is generated (“TripC ProgFail”). When using two
binary inputs, malfunctions in the trip circuit can be detected under all circuit breaker
conditions. When only one binary input is used, malfunctions in the circuit breaker
itself cannot be detected.
2.29.1 Functional Description
Monitoring with
Two Binary Inputs
(not connected to
common potencial)
When using two binary inputs, these are connected according to the following Figure,
parallel to the associated trip contact on one side, and parallel to the circuit breaker
auxiliary contacts on the other.
A precondition for use of trip circuit supervision is that the control voltage for the circuit
breaker is higher than the sum of minimum voltage drops at the two binary inputs (U
St
> 2 · U
BImin
). Since at least 19 V is needed for each binary input, monitoring can only
be used with a system control voltage above 38 V.
Figure 2-67 Principle of Trip Circuit Monitor with Two Binary Inputs (not connected to
common potential)
Monitoring with two binary inputs not only detects interruptions in the trip circuit and
loss of control voltage, it also monitors the response of the circuit breaker using the
position 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 Table 2-8), or not activated (logical condi-
tion "L").
With intact trip circuits the condition that both binary inputs are not actuated (”L") is
possible only during a short transition period (trip contact is closed, but circuit breaker
has not yet opened.) A continuous state of this condition is only possible when the trip
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