Automatic Reclosure Function (Optional) - Siemens SIPROTEC 7SA6 Manual

Functions
6.14

Automatic Reclosure Function (optional)

Pickup
aborted
Action
time
Trip
command
Close
command
Reclaim
time
start with 1st trip command
reclosure active
Fig. 6-101 Timing diagram of a double-shot reclosure with action time (2nd reclosure successful)
6-188
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 reclosed.
Reclosure is performed by an automatic reclosure function (AR). An example of the
normal time sequence of a double-shot reclosure is shown in Figure 6-101.
If the circuit-breaker poles can be operated individually, a single-pole auto-reclosure
is usually initiated in the case of single-phase faults and a three-pole auto-reclosure in
the case of multi-phase faults in the network with earthed system star point. If the fault
is still present after reclosure (arc not extinguished or metallic short-circuit), the pro-
tection issues a final trip. Several reclosure attempts are made in some networks.
Automatic reclosure is only permitted on overhead lines because the possibility of
automatic extinguishing of a fault 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 equip-
ment (e.g. overhead line in block with 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.
In the version with single-pole tripping, 7SA6 allows phase-segregated, single-pole
tripping. A single and three-pole, single and multiple shot automatic reclosure function
is integrated, depending on the ordered version.
7SA6 can also operate with an external automatic reclosure device. In this case the
signal exchange between 7SA6 and the external reclosure device must take place via
the binary inputs and outputs.
It is also possible to have the integrated automatic reclosure circuit initiated by an ex-
ternal protection (e.g. alternate protection). The use of two 7SA6 with automatic re-
closure function or the use of one 7SA6 with an automatic reclosure function and a
second protection with its own automatic reclosure function are equally possible.
dead time
1st reclosure
1st reclosure unsuccessful; further
tripping during reclaim time
aborted
dead time
2nd reclosure
aborted
reclaim
time
2nd reclosure successful, no further
tripping during reclaim time
7SA6 Manual
C53000-G1176-C156-2