Functions
2.11 Automatic Reclosure Function 79 (Optional)
SIPROTEC, 7SD80, Manual
E50417-G1140-C474-A1, Release date 09.2011
141
2.11
Automatic Reclosure Function 79 (Optional)
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 au-
tomatic reclosing function (AR).
Automatic reclosing is only permitted on overhead lines because the possibility of extinguishing a fault arc au-
tomatically 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 in block with a transformer or 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 pro-
tective elements will re-trip the circuit breaker.
The 7SD80 can also be implemented with an external automatic reclosing device. In this case, the signal ex-
change 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.
2.11.1
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.
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).