Siemens siprotec 7SA522 - Page 535

Technical Data
10-197SA522 Manual
C53000-G1176-C119-2
Logarithmic inverse:
Note: For currents I/,3 ≥ 35 the tripping time is constant.
Figure 10-4 Trip time characteristics of inverse time overcurrent protection with logarithmic
inverse characteristic
1 2 3 4 5 6 7 10 20 30 40
0
2
4
6
8
I/,3
t/s
7,3PD[
7,3PLQ
,3²)$&725
7,3
1,00
1,351,70
8
tT
3I0Pmax
T
3I0P
ln(I/3I0P)⋅
–=