ABB Relion 650 series RET650 Product Manual page 71

ABB
Transformer protection RET650
Product version: 1.1
Table 64. Inverse time characteristics for overvoltage protection
Function
Type A curve:
k
=
t
æ ö
- >
U U
ç ÷
è ø
>
U
EQUATION1436-SMALL V1 EN
U> = U
set
U = U
measured
Type B curve:
×
k 480
=
t
2.0
æ ö
- >
U U
ç × - ÷
32 0.5
è ø
>
U
EQUATION1437-SMALL V1 EN
Type C curve:
×
k 480
=
t
3.0
æ ö
- >
U U
ç × - ÷
32 0.5
è ø
>
U
EQUATION1438-SMALL V1 EN
Range or value
k = (0.05-1.10) in steps of
0.01 unless otherwise stated
k = (0.05-1.10) in steps of
0.01 unless otherwise stated
-
0.035
k = (0.05-1.10) in steps of
0.01 unless otherwise stated
-
0.035
1MRK 504 127-BEN -
Issued: February 2011
Accuracy
Class 5 +40 ms
71