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Protection and Automation Functions
6.17 Negative-Sequence Protection
General Functionality
6.17.3
6.17.3.1
Description
Logic
The following figure represents the logic of the general functionality which applies across all configured
stages. It contains:
•
Selection of the reference value
•
Current-release criterion
[lo_General Functionality.vsd, 1, en_US]
Figure 6-153
(1)
Switchover to I
Reference Value
With the parameter Reference value, the negative-sequence current I
current I
rated, obj
tion for low short-circuit currents is increased.
Current Limitation and Maximum Phase Current
With the parameters Current limitation Imax and Maximum phase current, you restrict the oper-
ating range of the function. When the limiting is activated, pickup of the stages is blocked as soon as the
maximum phase-current threshold value is exceeded. For more information, refer to the stage description.
Release Current
The threshold value of the Release current serves to release the negative-sequence protection.
6.17.3.2
Application and Setting Notes
Parameter: Reference value
•
Default setting (_:2311:106) Reference value = rated current
With the parameter Reference value, you define the normalization of the negative-sequence current I
the rated object current I
634
Logic Diagram of the General Functionality
with (_:2311:106) Reference value = pos. seq. current
1
or to the positive-sequence current I
(I
/I
) or to the positive-sequence current I
rated, obj
2
rated, obj
is normalized to the rated object
2
. When I
is normalized to I
1
2
SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
, the sensitivity of the func-
1
2
(I
/I
).
1
2
1
to
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