Siemens siprotec 7SD5 User Manual page 393

Table 2-17
The conditions of the two binary inputs are scanned periodically. A query takes place
about every 500 ms. If three consecutive conditional checks detect an abnormality, an
annunciation is reported (see Figure 2-169). The repeated measurements help to de-
termine the delay of the alarm message and to avoid that an alarm is output during
short-time transition periods. After the fault in the trip circuit is removed, the alarm is
reset automatically after the same time.
Figure 2-169
Supervision with The binary input is connected in parallel to the respective command relay contact of
One Binary Input the protection device according to Figure 2-170. The circuit breaker auxiliary contact
is bridged with a high-ohm 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
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".
7SD5 Manual
C53000-G1176-C169-1
Condition table for binary inputs, depending on RTC and CB position
No Trip contact Circuit breaker
.
1 Open ON
2 Open OFF
3 Closed ON
4 Closed OFF
Logic diagram of the trip circuit monitoring with two binary inputs
2.22 Monitoring Functions
AuxCont 1 AuxCont 2
Closed Open
Open Closed
Closed Open
Open Closed
> 2·U ). Since at least 19 V are
Ctrl BImin
BI 1 BI 2
H L
H H
L L
L H
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