ABB RED650 Technical Manual page 102

Section 6
Differential protection
96
Operate current
[ in pu of IBase]
5
4
3
A
2
1
IdMin
0
0
EndSection1
IEC05000300 V1 EN-US
Figure 34: Description of the restrained and the unrestrained operate
characteristics
where:
D
Ioperate
= ×
slope 100%
D
Irestrain
EQUATION1246 V1 EN-US
and where the restrained characteristic is defined
by the settings:
1. IdMin
2. EndSection1
3. EndSection2
4. SlopeSection2
5. SlopeSection3
The second analysis is the 2
differential currents. Occurrence of these harmonics over a level that is set
separately for each one blocks tripping action from the biased slope evaluation.
Operate
unconditionally
UnrestrainedLimit
Operate
conditionally
Section 1 Section 2
SlopeSection2
1 2
EndSection2
nd th
and 5 harmonic analysis of the three instantaneous
1MRK 505 394-UEN A
IdMinHigh
B
Section 3
SlopeSection3
Restrain
3 4 5
Restrain current
[ in pu of IBase]
en05000300.vsd
Line differential protection RED650 2.2 IEC
Technical manual
C