Siemens 6MD85, Manual

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Automatic Reclosing Function with Adaptive Dead Time (ADT)
Description
Description
It is also possible to set the dead times only at one line end and to configure the adaptive dead time at the
other end or ends. The requirements for this is that the voltage transformer aligned on the line side or a possi-
bility to transfer a close command to a remote line end exists.
Figure 7-53 shows an example with a voltage measurement. It is assumed that device I works with defined
dead times, while the adaptive dead time is configured in device II. It is important that the line is at least fed
from busbar A, so from the side with the defined dead times.
With the adaptive dead time, the automatic reclosing function at the line end II decides independently if and
when a reclosing is reasonable and permissible and when it is not. The criteria is the voltage of the line at the
end II, which is switched through after reclosing from end I. The reclosing at end II occurs, as soon as it exists,
so that the line from end I is set back under voltage. Basically, all phase-to-phase and phase-to-ground
voltages are monitored.
With an implied short-circuit, the lines at the positions I, II, and III in the example are switched off. Position I is
switched on again after the dead time set there. At position III the reduced dead time (RDT) can be executed
with the appropriate configuration (see chapter
7.2.4.18 Dead-Line Checking (DLC) and Reduced Dead Time
(RDT) ) if an infeed is also available on busbar B.
If the short circuit has been cleared after successful reclosing, the line A-B from the busbar A will be set under
voltage through the position I. Device II recognizes this voltage and switches on to warrant adequate voltage
measurement time after a short delay The system incident is thus successfully cleared.
If the short circuit is not cleared after closure at position I, I will be switched to the fault again. At line end II,
now no healthy voltage will appear. The device here recognizes this and does not close again.
With multiple reclosing, the process may repeat if the reclosing is unsuccessful until one of the reclosings is
successful or a final disconnection occurs.
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Figure 7-53 Example for Adaptive Dead Time (ADT)
As the example shows, the adaptive dead time brings along the following advantages:
•
The circuit breaker at position II does not switch off again with a remaining fault and is protected through
this.
•
With non-selective tripping by overreach at position III, no further disruption cycles may occur here
because the short-circuit path via busbar B and the position II remains disrupted even with multiple
reclosing.
•
At position I, with multiple reclosing and even with a final tripping, an overlapping is allowed, because
the line at position II remains open and thus, no actual overreaching can occur at position I.
The adaptive dead time also contains the reduced dead time (RDT), because the criteria are the same. A
special setting of the reduced dead time (RDT) is unnecessary if the automatic reclosing function is used with
adaptive dead time (ADT).
7.2.5
7.2.5.1
Protection and Automation Functions
7.2 Automatic Reclosing Function
580 SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017