Siemens siprotec 7SA522, User Manual

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Functions
6-223
7SA522 Manual
C53000-G1176-C119-2
A continuous occurrence of this state is only possible during interruption or short cir-
cuit of the trip circuit as well as during failure of the battery supply voltage, or faults in
the mechanism of the circuit breaker.
The two binary inputs are periodically interrogated to determine their state. An interro-
gation takes place every 500 ms. Only once n = 3 sequential state interrogations de-
tect a failure, will the failure alarm be generated (refer to Figure 6-119). Due to this
measurement repetition the delay of the failure alarm is determined. A failure alarm
due to transient transition phases is thereby avoided. After removal of the failure in the
trip circuit, the alarm automatically resets after the same time.
Figure 6-119 Logic diagram of the trip circuit supervision with two binary inputs
Monitoring with
One Binary Input The binary input is connected in parallel to the corresponding trip relay of the protec-
tion according to Figure 6-120.The circuit breaker auxiliary contact is bridged by
means of a high resistance shunt R.
The control voltage of the circuit breaker should be approximately twice the minimum
voltage drop across the binary input (U
C
> 2 ·U
BImin
). As at least 19 V are required for
the binary input, the monitoring function can be implemented if the plant control volt-
age is greater than approximately 38 V.
An calculation example for the resistance shunt R is shown in subsection 8.1.2, mar-
gin Trip Circuit Supervision.
Table 6-5 Condition table of the binary inputs depending on the Trip relay state and
CB state
No. Trip
relay
Circuit
breaker
Auxiliary
contact 1
Auxiliary
contact 2
BI 1 BI 2
1 open ON closed open H L
2 open OFF open closed H H
3 closed ON closed open L L
4 closed OFF open closed L H
&
T T
T approx. 1 to 2 s
6854 >Trip C1 TripRel
6855 >Trip C1 BKr.Rel
6865 Fail: Trip cir.