Figure 258: Positive direction of current
Instantaneous high stage
The differential protection includes an unbiased instantaneous high stage. The
instantaneous stage operates and the OPR_HS output is activated when the
amplitude of the fundamental frequency component of the differential current
exceeds the set
High operate value
or when the instantaneous peak values of the
differential current exceed 2.5 ·
High operate value
. The factor 2.5 (= 1.8 · √2) is due
to the maximum asymmetric short circuit current.
The OPERATE output is always activated when the OPR_HS output activates.
The internal blocking signals of the function block do not prevent the operation of
the instantaneous stage. When required, the operate signal due to instantaneous
operation can be blocked by the binary inputs BLK_OPR_HS or BLOCK.
1MRS757644 H
Protection functions
620 series
Technical Manual
507
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