Functions
2.9 Ground Fault Protection 50N(s), 51N(s)
SIPROTEC, 7SJ61, Manual
C53000-G1140-C210-1, Release date 02.2008
153
Table 2-7
Preferential values of standardized currents for user-defined tripping curves
Figure 2-53
Use of a user-defined characteristic
Note Regarding Settings List for Sensitive Ground Fault Detection
In devices with sensitive ground fault input, which is independent of the nominal current rating of the device,
settings may in general also be entered as primary values under consideration of the current transformer ratio.
However, problems related to the resolution of the pickup currents can occur when very small settings and
small nominal primary currents are given. The user is therefore encouraged to enter settings for the sensitive
ground fault detection in secondary values.
MofPU = 1 to 1.94
MofPU = 2 to 4.75
MofPU = 5 to 7.75
MofPU = 8 to 20
1.00
1.50
2.00
3.50
5.00
6.50
8.00
15.00
1.06
1.56
2.25
3.75
5.25
6.75
9.00
16.00
1.13
1.63
2.50
4.00
5.50
7.00
10.00
17.00
1.19
1.69
2.75
4.25
5.75
7.25
11.00
18.00
1.25
1.75
3.00
4.50
6.00
7.50
12.00
19.00
1.31
1.81
3.25
4.75
6.25
7.75
13.00
20.00
1.38
1.88
14.00
1.44
1.94