Automatic Reclosure Function (optional) 79
Experience shows that about 85% of the arc faults on overhead lines are extinguished automatically after
being tripped by the protection. This means that the line can be connected again. Reclosing is performed by
an automatic reclosing function (AR).
Automatic reclosing is only permitted on overhead lines because the possibility of extinguishing a fault arc
automatically only exists there. It must not be used in any other case. If the protected object consists of a
mixture of overhead lines and other equipment (e.g. overhead line/cable), it must be ensured that reclosing
can only be performed in the event of a short circuit on the overhead line.
If the fault still exists after automatic reclosing (arc has not disappeared, there is a metallic fault), then the
protective elements will re-trip the circuit breaker.
The 7SD80 can also be implemented with an external automatic reclosing device. In this case, the signal
exchange between 7SD80 and the external reclosing device must be effected via binary inputs and outputs.
It is also possible to initiate the integrated auto reclose function by an external protection device (e.g. a
backup protection). The use of two 7SD80 with automatic reclosing function or the use of one 7SD80 with an
automatic reclosing function and a second protection with its own automatic reclosing function are equally
possible.
Functional Description
Reclosing following interruption by a short-circuit protection is performed by an automatic reclosing function
(AR). An example of the normal time sequence of double reclosing is shown in the figure below.
[ablaufdia-2-mal-we-wirkzeit-wlk-310702, 1, en_US]
Figure 2-54 Timing diagram of a double-shot reclosure with action time (2nd reclosure successful)
The integrated automatic reclosing function allows up to 2 reclosing attempts using different parameters
(action times and dead times).
Initiation
Initiation of the automatic reclosing function means storing the first trip signal of a power system fault that
was generated by a protection function which operates with the automatic reclosing function, e.g. phase
comparison protection or ground fault differential protection. In case of multiple reclosing attempts, initiation
therefore only takes place once with the first trip command. This storing of the first trip signal is the prerequi-
site for all subsequent activities of the automatic reclosing function. The initiation is important if the first trip
command only appears after an action time has expired (see below under “Action times”).
2.11
2.11.1
Functions
2.11 Automatic Reclosure Function (optional) 79
SIPROTEC 4, 7SD80, Manual 131
E50417-G1100-C474-A2, Edition 02.2018
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