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2.9
Trip Supervision
The trip supervision function checks whether the circuit breaker has tripped correctly
in case of an external trip or a trip command by an additional current flow monitoring.
2.9.1
Functional Description
After the circuit breaker has tripped, the device checks that no current flows, or only a
current below a certain threshold, once the supervision time has elapsed.
To start this supervision, the TRIP command is detected at the circuit breaker. This
command must be configured to the signal „>Ext. CB Trip" (FNo.1438).
The maximum duration of the supervision can be set with the parameter T I> CB MAX
at address 2922.
If the current flow has not been interrupted 100 ms after a TRIP command has been
detected, the indication „CB Fault" (FNo. 1491) is output.
This indication is reset before the set supervision has elapsed if the device detects that
the current flow has been interrupted, or if the signal „>Ext. CB Trip" (FNo.1438)
indicates that the external TRIP signal has been reset.
The interruption of the current flow is monitored by a current threshold.
When this threshold, which is set with the parameter I> CB (address: 2921), is un-
dershot, the current flow is considered to be interrupted.
The measuring function works with an intelligent method for fast detection of a current
interruption. If the current signal contains decaying aperiodic components caused by
the current transformers, these components are identified as such, and the current in-
terruption is detected.
The figure below shows the logic diagram of the circuit breaker trip supervision.
Figure 2-30
7ST6 Manual
E50417-G1176-C251-A3
Circuit breaker trip supervision
2.9 Trip Supervision
109
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