ABB RELION RET670 - Page 145

Section 1
Operate
conditionally
UnrestrainedLimit
Section 2
Section 3
Restrain
Operate
unconditionally
5
4
3
2
1
0
0 1 2 3 4 5
IdMin
EndSection1
EndSection2
restrain current
[ times IBase ]
operate current
[ times IBase ]
SlopeSection2
SlopeSection3
en05000187-2.vsd
IEC05000187 V2 EN-US
Figure 48: Representation of the restrained, and the unrestrained operate
characteristics
100%
Ioperate
slope
Irestrain
D
=
D
×
EQUATION1246 V1 EN-US (Equation 13)
and where the restrained characteristic is defined by the settings:
1.
IdMin
2. EndSection1
3. EndSection2
4. SlopeSection2
5. SlopeSection3
1MRK 504 163-UUS A Section 7
Differential protection
Transformer protection RET670 2.2 ANSI 139
Application manual