Siemens siprotec 7SA6 User Manual page 649

100
t [s]
30
20
10
5
3
2
1
0.5
0.3
0.2
0.1
0.05
1 2 3
VERY INVERSE
t =
100
t [s]
30
20
10
5
3
2
1
0.5
0.3
0.2
0.1
0.05
1 2 3
DEFINITE INVERSE
Figure 10-3 Trip time characteristics of inverse time overcurrent protection, acc. ANSI/IEEE (phases and earth)
7SA6 Manual
C53000-G1176-C133-1
D [s]
15
10
5
2
1
0.5
5 10 20
I/I
p
 
3,922
⋅
 
[s]
-------------------------- - + 0.0982 D
 2 
( ⁄ )
I I 1
–
p
D [s]
15
10
5
2
1
0.5
5 10 20
I/I
p
 
0.4797
 
t = ------------------------------------- - + 0.21359
 1.5625 
( ⁄ )
I I 1
–
p
100
t [s]
30
20
10
5
3
2
1
0.5
0.3
0.2
0.1
0.05
1
EXTREMELY INVERSE
t
D
I
I
p
Note: For earth fault read 3I
stead of I
⋅
[s]
D
0.5
1
2 3 5 20
10
I/I
p

5.64

t = -------------------------- - +
 2
( ⁄ )
I I – 1
p
Trip time
Setting value time multiplier
Fault current
Setting value current
and D instead of D
p 3I0p
Technical Data
D [s]
15
10
5
2

 ⋅
0.02434 D
[s]

in-
0p
Ip
10-21