Functions
6-1557SJ62 Manual
C53000-G1140-C121-1
A condition for the use of trip circuit monitoring is that the control voltage for the circuit
breaker is greater than the sum of the minimum voltage drops of both binary inputs
(V
St
> 2 ⋅ V
BImin
). Since at least 17 V are needed for each binary input, the monitor can
only be used with a system control voltage of over 35 V.
Figure 6-64 Principle of Trip Circuit Monitor with Two Binary Inputs
Monitoring with binary inputs not only detects interruptions in the trip circuit and loss
of control voltage, it also monitors the response of the circuit breaker using the position
of the circuit breaker auxiliary contacts.
Depending on the conditions of the trip contact and the circuit breaker, the binary in-
puts are activated (logical condition “H” in Table 6-5), or not activated (logical condition
“L”).
Even for healthy trip circuits the condition that both binary inputs are not actuated (“L”)
is possible during a short transition period (trip contact is closed, but the 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, a loss of battery
voltage occurs, or malfunctions occur with the circuit breaker mechanism.
1
) Trip Circuit is faulty
Table 6-5 Condition Table for Binary Inputs, Depending on RTC and CB Position
No. Relay Trip
Contact
Circuit
Breaker
52a Contact 52b Contact BI 1 BI2
1 Open Closed Closed Open H L
2 Open Open Open Closed H H
3
1
)
Closed Closed Closed Open L L
4
1
)
Closed Open Open Closed L H
V–
V+
RTC
52b52a
V
BI1
V
BI2
>74 TC trip rel.
>74 TC brk.rel
V
St
7SJ62
7SJ62
52TC
Legend:
RTC — Trip Contact
52 — Circuit Breaker
52TC — Circuit Breaker Trip Coil
52a — Circuit Breaker Auxiliary Contact
(closed when 52 is closed)
52b — Circuit Breaker Auxiliary Contact
(closed when 52 is open)
V
St
— Control Voltage
V
BI1
— Input Voltage for 1st Binary Input
V
BI2
— Input Voltage for 2nd Binary Input
Note:
The above diagram refers to a closed circuit
breaker position
)
)
52
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