Siemens siprotec 7SA522 - Page 534

Technical Data
10-18 7SA522 Manual
C53000-G1176-C119-2
Figure 10-3 Trip time characteristics of inverse time overcurrent protection, acc. ANSI/IEEE (phases and earth)
DEFINITE INVERSE
D [s]
I / I
p
1
2
5
10
15
0.5
1
0.3
0.1
1 2 3 5 10 20
100
20
10
5
2
0.5
0.2
0.05
VERY INVERSE
EXTREMELY INVERSE
D [s]
t [s]
t [s]
I / I
p
I / I
p
1
2
5
10
15
0.5
D [s]
1
2
5
10
15
0.5
1
0.3
0.1
1 2 3 5
10
20
100
20
10
5
2
0.5
0.2
0.05
[s]
1 2 3 5 10 20
0.3
0.1
100
20
10
2
0.05
5
[s]
0.2
0.5
1
t [s]
3
t
3,922
II
p
⁄()
2
1
–
---------------------------
0.0982
+



D⋅
=
t
5.64
II
p
⁄()
2
1
–
---------------------------
0.02434
+



D⋅
=
t
0.4797
II
p
⁄()
1.5625
1
–
--------------------------------------
0.21359
+



D⋅
=
30
3
3
[s]
30
30
t Trip time
D Setting value time multiplier
I Fault current
I
p
Setting value current
Note: For earth fault read 3I
0p
in-
stead of I
p
and D
3I0p
instead of D
Ip