Table 71. 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
I = I
measured
/I
set
k = (0.05-999) in steps of 0.01
RD type logarithmic inverse characteristic
5.8
1.35
=
-
×
æ
ö
ç
÷
è
ø
t
I
In
k
EQUATION1138-SMALL V1 EN
I = I
measured
/I
set
k = (0.05-999) in steps of 0.01
Table 72. 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
U> = U
set
U = U
measured
k = (0.05-1.10) in steps of 0.01
±5% +60 ms
Type B curve:
2.0
480
32
0.5
0.035
=
×
-
>
×
-
-
>
æ
ö
ç
÷
è
ø
t
k
U
U
U
EQUATION1437-SMALL V1 EN
k = (0.05-1.10) in steps of 0.01
Type C curve:
3.0
480
32
0.5
0.035
=
×
-
>
×
-
-
>
æ
ö
ç
÷
è
ø
t
k
U
U
U
EQUATION1438-SMALL V1 EN
k = (0.05-1.10) in steps of 0.01
Transformer protection RET650
1MRK 504 137-BEN B
Product version: 1.3
58
ABB
