Siemens Siprotec 7UM611 Manual page 178

2 Functions
Depending on the conditions of the trip contact and the circuit breaker, the binary
inputs are activated (logical condition "H" in the following Table), or not activated (log-
ical condition "L").
Table 2-9
With this solution, it is impossible to distinguish between status 2 ("normal operation
with open CB LS" and "KR triggered successfully"). However these two statuses are
normal and thus not critical. Status 4 is only theoretical and indicates a hardware error.
With intact trip circuits the condition that both binary inputs are not actuated ("L") is
possible only during a short transition period (trip contact is closed, but circuit breaker
has not yet opened.) A continuous state of this condition is only possible when the trip
circuit has been interrupted, a short-circuit exists in the trip circuit, battery voltage
failure occurs, or malfunctions occur with the circuit breaker mechanism. Accordingly
it is used as monitoring criterion.
The conditions of the two binary inputs are scanned periodically. A query takes place
about every 600 ms. If three consecutive conditional checks detect an abnormality
(after 1.8 s), an annunciation is reported (see Figure 2-68). The repeated measure-
ments 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.
Monitoring with The binary input is connected in parallel to the respective command relay contact of
One Binary Input the protection device according to the following figure. The circuit breaker auxiliary
contact is bridged with a high-ohm substitute resistor R.
The control voltage for the circuit breaker should be at least twice as high as the
minimum voltage drop at binary input (U
activate a binary input is 19 V, about 38 V is required for monitoring a power station
side control voltage.
178
Condition Table for Binary Inputs, Depending on RTC and CB Position
No. Trip Circuit
contact breaker
1 Open TRIP
2 Open or CLOSE
Closed
3 Closed TRIP
4 Open TRIP or
CLOSE
AuxCont AuxCont BI 1
1 2
Closed Open H
Open Closed L
Closed Open L
Closed Closed H
> 2 · U
St BImin
BI 2 dyn. status stat. status
L normal operation with
closed CB
H normal operation with
open CB or RTC has
tripped successfully
L Transi- Fault
tion/fault
H Theoretical status:
AuxCont defective, BI
defective, wrong connec-
tion
Since the minimum voltage to
7UM61 Manual
C53000-G1176-C127-3