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2 Functions
2.10
Automatic Reclosure Function (optional)
Experience shows that about 85% of the arc faults on overhead lines are extinguished
automatically after being tripped by the protection. The line can therefore be re-ener-
gised. Reclosure is performed by an automatic reclose function (AR).
Automatic reclosure is only permitted on overhead lines because the option of auto-
matic extinguishing of a fault arc only exists there. It should not be used in any other
case. If the protected object consists of a mixture of overhead lines and other equip-
ment (e.g. overhead line directly connected to a transformer or overhead line/cable),
it must be ensured that reclosure can only be performed in the event of a fault on the
overhead line.
If the circuit breaker poles can be operated individually, a single-pole automatic reclo-
sure is usually initiated in the case of single-phase faults and a three-pole automatic
reclosure in the case of multi-phase faults in the network with earthed system star
point. If the fault still exists after reclosure (arc not extinguished or metallic short-cir-
cuit), the protection issues a final trip. In some systems several reclosing attempts are
performed.
In the model with single-pole tripping the 7SD610 allows phase-selective single-pole
tripping. A single- and three-pole, one- and multi-shot automatic reclosure is integrat-
ed depending on the order variant.
The 7SD610 can also operate in conjunction with an external automatic reclosure
device. In this case, the signal exchange between 7SD610 and the external reclosure
device must be effected via binary inputs and outputs.
It is also possible to initiate the integrated auto reclose function by an external protec-
tion device (e.g. a backup protection). The use of two 7SD610 with automatic reclo-
sure function or the use of one 7SD610 with an automatic reclosure function and a
second protection with its own automatic reclosure function is also possible.
2.10.1 Function Description
Reclosure is performed by an automatic reclosure circuit (ARC). An example of the
normal time sequence of a double reclosure is shown in the figure below.
122
7SD610 Manual
C53000-G1176-C145-4
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