ABB Relion 650 series RET650 Product Manual page 72

Transformer protection RET650
Product version: 1.1
Table 65. Inverse time characteristics for undervoltage protection
Function
Type A curve:
k
=
t
æ ö
< -
U U
ç ÷
è ø
<
U
EQUATION1431-SMALL V1 EN
U< = U
set
U = UV
measured
Type B curve:
×
k 480
=
t
2.0
æ ö
< -
U U
ç × - ÷
32 0.5
è ø
<
U
EQUATION1432-SMALL V1 EN
U< = U
set
U = U
measured
72
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
+
0.055
1MRK 504 127-BEN -
Issued: February 2011
Accuracy
Class 5 +40 ms
ABB