Table 159. RI and RD type inverse time characteristics
Function
Range or value
Accuracy
RI type inverse characteristic
1
0.236
0.339
=
×
-
t
k
I
EQUATION1137-SMALL V1 EN-US
I = I
measured
/I
set
0.05 ≤ k ≤ 999.00
1.5 x I
set
≤ I ≤ 20 x I
set
IEC 60255-151, ±2.0%
or ±40 ms whichever is
greater
RD type logarithmic inverse
characteristic
5.8
1.35
=
-
×
æ
ö
ç
÷
è
ø
t
I
In
k
EQUATION1138-SMALL V1 EN-US
I = I
measured
/I
set
SEMOD116978-2 v9
Table 160. Inverse time characteristics for overvoltage protection
Function
Range or value
Accuracy
Type A curve:
=
-
>
>
æ
ö
ç
÷
è
ø
t
k
U
U
U
EQUATION1436-SMALL V1 EN-US
U> = U
set
U = U
measured
k = (0.05-1.10) in steps of 0.01
±5.0% or ±45 ms
whichever is greater
Type B curve:
2.0
480
32
0.5
=
⋅
−
>
⋅
−
0.035
+
>
t
k
U U
U
EQUATION1437-SMALL V2 EN-US
k = (0.05-1.10) in steps of 0.01
Type C curve:
3.0
480
32
0.5
=
⋅
⋅
−
−
>
0.035
+
>
t
k
U U
U
EQUATION1438-SMALL V2 EN-US
k = (0.05-1.10) in steps of 0.01
Programmable curve:
×
=
+
-
>
×
-
>
æ
ö
ç
÷
è
ø
P
k A
t
D
U
U
B
C
U
EQUATION1439-SMALL V1 EN-US
k = (0.05-1.10) in steps of 0.01
A = (0.005-200.000) in steps of 0.001
B = (0.50-100.00) in steps of 0.01
C = (0.0-1.0) in steps of 0.1
D = (0.000-60.000) in steps of 0.001
P = (0.000-3.000) in steps of 0.001
1MRK 504 155-BEN F
Transformer protection RET670 2.1 IEC
ABB
121
