Siemens SIPROTEC 7SD610 Manual page 132

Functions
2.10 Automatic Reclosure Function (optional)
There are also various selectable possibilities for the response of the internal auto- reclose function to a de-
tected evolving fault.
• EV. FLT. MODE Stops AutoRecl:
The reclosure is blocked as soon as a sequential fault is detected. The tripping by the sequential fault is
always 3-pole. This applies irrespective of whether 3-pole cycles have been permitted or not. There are no
further reclosure attempts; the automatic reclosure function is blocked dynamically (see also margin heading
„Blocking reclosure", above).
• EV. FLT. MODE starts 3p AR:
As soon as a sequential fault is detected, the recloser switches to a 3-pole cycle. Each trip command is 3-
pole. The separately settable dead time for sequential faults starts with the clearance of the sequential fault;
after the dead time the circuit breaker receives a close command. The further sequence is the same as for
1- and 3-pole cycles.
The complete dead time in this case consists of the part of the dead time for the 1-pole reclosure up to the
clearance of the sequential fault plus the dead time for the sequential fault. This makes sense because the
duration of the 3-pole dead time is most important for the stability of the network.
If reclosure is blocked due to a sequential fault without the protection issuing a 3-pole trip command (e.g. for
sequential fault detection with starting), the device can send a 3-pole trip command so that the circuit breaker
does not remain open with one pole (forced 3-pole trip).
Forced 3-pole trip
If reclosure is blocked during the dead time of a 1-pole cycle without a 3-pole trip command having been initi-
ated, the breaker would remain open at one pole. In most cases, the circuit breaker is equipped with a pole
discrepancy supervision which will trip the remaining poles after a few seconds. By setting a parameter, you
can achieve that the tripping logic of the device immediately sends a 3-pole trip command in this case. This
forced 3-pole trip pre-empts the pole discrepancy supervision of the CB because the forced 3-pole trip of the
device is initiated as soon as the reclosure is blocked following a 1-pole trip or if the CB auxiliary contacts report
an implausible breaker state.
When different internal protection functions initiate a 1-pole trip in different phases, the device will issue a 3-
pole trip command due to the tripping logic (Section 2.16.1), independent of this forced 3-pole trip. This is also
true for trip commands given via the direct local trip inputs (Section 2.6) or the reception of a remote trip (Sec-
tion 2.7) since these signals directly affect the tripping logic of the device.
If the device trips 1-pole and if an external trip command in another phase only reaches the device via one of
the binary inputs, e.g. „>Trip L1 AR" to the internal automatic reclosure function, this is not routed to the
tripping logic. In this case, 3-pole trip is ensured only if the forced 3-pole trip is effective.
The forced 3-pole trip is also activated when only 3-pole cycles are allowed, but a 1-pole trip is signalled exter-
nally via a binary input.
Dead Line Check (DLC)
If the voltage of a disconnected phase does not disappear following a trip, reclosure can be prevented. A pre-
requisite for this function is that the voltage transformers are connected on the line side of the circuit breaker.
To select this function the dead line check must be activated. The automatic reclosure function then checks the
disconnected line for no-voltage: the line must have been without voltage for at least an adequate measuring
time during the dead time. If this was not the case, the reclosure is blocked dynamically.
This no-voltage check on the line is of advantage if a small generator (e.g. wind generator) is connected along
the line.
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SIPROTEC, 7SD610, Manual
C53000-G1176-C145-6, Release date 02.2011