2 Functions
50
7UM61 Manual
C53000-G1176-C127-3
Figure 2-8
Definition of Parameters 1304 Phase Direction and 1305 LINE ANGLE
The setting value of the direction straight line results from the short-circuit angle of the
feeding network. As a rule, it will be 60
°
. The current pickup value results from the
short-circuit current calculation. Workable pickup values are situated at about (1.5 to
2) · I
N, G
. A short tripping delay (TI>>
≈
0.05 s to 0.1 s) is required to ensure that bal-
ancing procedures are finished.
Application Exam-
ple: Motor Protec-
tion
For motors that have no no separate current transformer in the starpoint, the following
figure shows how to use the I>> stage as "differential protection". The configuration of
the protection function depends on the transformers. Since this application is most
likely to be used for replacements in an existing system, the settings of that system
should be the basis for this.
Figure 2-9
I>> Stage as "Differential Protection"
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