Siemens 7SJ82 Manual page 855

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Figure 6-260
The monitoring is started if one of the following conditions is met:
•
The circuit-breaker position is detected as open via the circuit-breaker auxiliary contacts during the time
set with the parameter Position recognition delay.
The Position recognition delay time is used for safety means to ensure that the circuit breaker is
definitely open when the monitoring starts. This parameter allows to adapt this start criterion to all kinds
of auxiliary-contact configurations.
•
The binary input signal
For safety reasons, the input signal has a preset software filtering time of 20 ms.
In addition to the active start criterion, the plausibility release (refer to the
must be present to start the monitoring duration.
With the fulfilled start condition, the Monitoring duration timer is started. This timer defines how long
the current signal is monitored regarding restriking. If the time expires, the monitoring is terminated.
The monitoring is also terminated immediately if one of the following conditions is met:
•
The circuit-breaker position is detected no longer as open.
•
A close command is given by the device.
•
The binary input signal
For safety reasons, the input signal has a preset software filtering time of 20 ms.
Measuring Value, Pickup/Dropout
During the Monitoring duration, the current signal is monitored phase-selectively regarding restriking.
As a measuring value, the fundamental component of the current is used.
•
On one hand, current peaks are damped but still detected reliably by the fundamental-component value.
•
On the other hand, a DC (Direct Current) component is suppressed. A DC component can occur after
switching off the circuit breaker.
Thus, the fundamental-component value is a good choice for a reliable restrike detection.
If any phase current exceeds the set current threshold value, the function picks up. The coming pickup indi-
cates the first restrike current pulse. With the pickup, the operate delay timers are started, see also the
following description
SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
Logic Diagram for Start/Stop Monitoring of the Circuit-Breaker Restrike Protection
>Start is activated.
>Stop is activated.
Delay/Tripping, Page 856.
Protection and Automation Functions
6.42 Circuit-Breaker Restrike Protection
Plausibility Release, Page 853)
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