Automatic Reclosing System 79
From experience, about 85 % of insulation faults associated with overhead lines are arc short circuits which
are temporary in nature and disappear when protection takes effect. This means that the line can be
connected again. The reconnection is accomplished after a dead time via the automatic reclosure function.
If the fault still exists after automatic reclosure (arc has not disappeared, there is a metallic fault), then the
protective elements will re-trip the circuit breaker. In some systems, several reclosing attempts are performed.
Applications
•
The automatic reclosure system integrated in the 7SJ80 can also be controlled by an external protection
device (e.g. backup protection). For this application, a signal exchange must occur between 7SJ80 and
the external protection device via binary inputs and outputs.
•
It is also possible to allow the relay 7SJ80 to work in conjunction with an external reclosing device.
•
The automatic reclosure system can also operate in interaction with the integrated synchronization func-
tion or with an external synchrocheck.
•
Since the automatic reclosing function is not applied when the 7SJ80 is used to protect generators,
motors, transformers, cables and reactors etc., it should be disabled for this application.
Program Execution
The 7SJ80 is equipped with an integrated three-pole, single-shot and multi-shot automatic reclosure (AR).
Figure 2-100 shows an example of a timing diagram for a successful second reclosure.
2.15
2.15.1
Functions
2.15 Automatic Reclosing System 79
SIPROTEC 4, 7SJ80, Manual 209
E50417-G1140-C343-A8, Edition 12.2017
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