2.15 Monitoring Functions
217
7SD610 Manual
C53000-G1176-C145-4
The conditions of the two binary inputs are checked periodically. A query takes place
about every 500 ms. If three consecutive conditional checks detect an abnormality, a
fault indication is output (see Figure 2-91). The repeated measurements determine the
delay of the alarm message and avoid that an alarm is output during short transition
periods. After clearance of the failure in the trip circuit, the failure alarm automatically
resets with the same time delay.
Figure 2-91 Logic diagram of the trip circuit monitoring with two binary inputs
Supervision with
One Binary Input
According to Figure 2-92, 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 equivalent 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 equivalent resistor R is shown in the configuration notes
in Section „Mounting and Connections“, margin heading „Trip Circuit Supervision“.
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