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[loocp3pha-210812-01.vsd, 1, en_US]
Figure 6-20
6.3.7.2
Application and Setting Notes
Parameter: Blk. w. inrush curr. detect.
•
Default setting (_:661:27) Blk. w. inrush curr. detect. = no
Parameter Value
no
yes
6.3.8
Influence of Other Functions via Dynamic Settings
6.3.8.1
Description
The parameters Threshold and Operate delay used for tripping are so-called dynamic settings.
Depending on other functions, the settings of these parameters can be changed dynamically (see
SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
Part-Logic Diagram on the Influence of Inrush-Current Detection Exemplified by the 1st Defi-
nite-Time Overcurrent Protection Stage
Description
The transformer inrush-current detection does not affect the stage.
Select this setting in the following cases:
•
In cases where the device is not used on transformers.
•
In cases where the device is used on transformers and the threshold
value of the stage is set above the maximum inrush current of the
transformer. This, for example, applies to the high-current stage that is
set such according to the short-circuit voltage V
that it only picks up on faults from the high-voltage side. The trans-
former inrush current cannot become larger than the maximum trans-
mittable short-circuit current.
When the transformer inrush current detection detects an inrush current
that would lead to a tripping of the stage, the start of the time delay and
tripping of the stage are blocked.
Select this setting if the device is used on transformers and the threshold
value of the stage is set below the maximum inrush current of the trans-
former. This applies to the overcurrent-protection stage, which is used as a
backup stage with grading time for faults on the undervoltage side of the
transformer.
Protection and Automation Functions
6.3 Overcurrent Protection, Phases
of the transformer
sc
355
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