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2 Functions
Pickup of the
Figure 2-23 shows the logic diagram for differential protection. The phase-segregated
Differential
stages are totalled to phase information. Additionally the device provides information
Protection
of which stage picked up.
Figure 2-23
Pickup logic for the differential protection function
As soon as the differential protection function registers a fault within its tripping zone,
the signal „Diff. Gen. Flt." (general device pickup of the differential protection)
is issued. For the differential protection function itself, this pickup signal is of no
concern since the tripping conditions are available at the same time. This signal, how-
ever, is necessary for the initiation of internal or external supplementary functions (e.g.
fault recording, automatic reclosure).
Tripping Logic of
The tripping logic of the differential protection combines all decisions of the differential
the Differential
stages and forms output signals which are also influenced by the central tripping logic
Protection
of the entire device (Figure 2-24).
The pickup signals that identify the concerned stages of the differential protection can
be delayed via the time stage T-DELAY I-DIFF>. Independently from this condition,
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7SD5 Manual
C53000-G1176-C169-1
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