Siemens 7SJ85 - General Functionality; Description; Application and Setting Notes

General Functionality
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 Logic Diagram of the General Functionality
(1) Switchover to I
1
with (_:2311:106) Reference value = pos. seq. current
Reference Value
With the parameter Reference value, the negative-sequence current I
2
is normalized to the rated object
current I
rated, obj
or to the positive-sequence current I
1
. When I
2
is normalized to I
1
, the sensitivity of the func-
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.
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
2
to
the rated object current I
rated, obj
(I
2
/I
rated, obj
) or to the positive-sequence current I
1
(I
2
/I
1
).
6.17.3
6.17.3.1
6.17.3.2
Protection and Automation Functions
6.17 Negative-Sequence Protection
634 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017