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Functions
2.14 Monitoring Functions
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
The repeated measurements help to determine 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.
[logikdiagramm-auskruebrwchg-2-be-wlk-310702, 1, en_US]
Figure 2-74
Monitoring with One Binary Input
The binary input is connected in parallel to the respective command relay contact of the protection device
according to
Figure
The control voltage for the circuit breaker should be at least twice as high as the minimum voltage drop at the
binary input (V
Ctrl
with a system control voltage higher than 38 V.
A calculation example for the resistance shunt R is shown in the configuration notes in Section "Mounting and
Connections", margin "Trip Circuit Supervision".
[prinzip-ausloesekrueb-1-be-wlk-010802, 1, en_US]
Figure 2-75
TCR
Relay trip contact
52
Circuit breaker
52TC
Circuit-breaker trip coil
52a
Circuit-breaker auxiliary contact (NO contact)
52b
Circuit-breaker auxiliary contact (NC contact)
V-Ctrl
Control Voltage for trip circuit
V-BI
Input voltage for binary input
R
Bypass resistor
VR
Voltage at 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 monitoring circuit is closed by either the circuit-breaker auxiliary contact
164
Logic diagram of the trip circuit monitoring with two binary inputs
2-75. The circuit-breaker auxiliary contact is bridged with a high-ohm substitute resistor R.
> 2·V
). Since at least 19 V are necessary at the binary input, this supervision can be used
BImin
Principle of the trip circuit monitoring with one binary input
Figure
SIPROTEC 4, 7SD80, Manual
E50417-G1100-C474-A2, Edition 02.2018
2-74).
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