this condition is only possible when the trip circuit has been interrupted, 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 supervision criterion.
Table 2-5 Condition table for binary inputs, depending on RTC and CB position
No. Trip contact Circuit breaker 52a Contact 52b Contact BI 1 BI 2
1 Open Closed Closed Open H L
2 Open Open Open Closed H H
3 Closed Closed Closed Open L L
4 Closed Open Open Closed L H
The conditions of the two binary inputs are checked periodically. A check takes place about every 600 ms. If
three consecutive conditional checks detect an abnormality (after 1.8 s), an annunciation is reported (see
Figure 2-47). The repeated measurements determine the delay of the alarm message and avoid that an alarm
is output during short transition periods. After the malfunction in the trip circuit is cleared, the fault annuncia-
tion is reset automatically after the same time period.
[7sj6x_ausloesekreis_2_binaerein-150502-kn, 1, en_US]
Figure 2-47 Logic diagram of the trip circuit supervision with two binary inputs
Supervision with One Binary Input
The binary input is connected according to the following figure in parallel with the associated trip contact of
the protection relay. The circuit breaker auxiliary contact is bridged with a bypass resistor R.
[prinzip-ausloesekreisueberwachung-1-binein-150502-kn, 1, en_US]
Figure 2-48
Trip circuit supervision with one binary input
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 52a circuit breaker auxiliary
Functions
2.8 Monitoring Functions
SIPROTEC 4, 7SJ61, Manual 127
C53000-G1140-C210-6, Edition 05.2016
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