Siemens siprotec SJ62 User Manual page 197

2 Functions
Supervision with
One Binary Input
195
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 2-63). The repeated measure-
ments 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 annunciation is reset automatically after the same time period.
Figure 2-63 Logic diagram of the trip circuit supervision with two binary inputs
The binary input is connected according to the following figure in parallel with the as-
sociated trip contact of the protection relay. The circuit breaker auxiliary contact is
bridged with a bypass resistor R.
Figure 2-64 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 contact (if the circuit breaker is closed) or
through the bypass resistor R by the 52b circuit breaker auxiliary contact. Only as long
as the trip contact is closed, the binary input is short circuited and thereby deactivated
(logical condition "L").
If the binary input is continuously deactivated during operation, this leads to the con-
clusion that there is an interruption in the trip circuit or loss of control voltage.
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015