Section 1
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
[ in pu of IBase]
Operate current
[ in pu of IBase]
SlopeSection2
SlopeSection3
en05000300.vsd
Operate
conditionally
IdMinHigh
A
C
B
IEC05000300 V1 EN-US
Figure 55: Restrained differential function characteristic (reset ratio 0.95)
where:
100%
Ioperate
slope
Irestrain
D
= D
×
EQUATION1246 V1 EN-US
Line differential protection is phase-segregated where the operate current is the vector sum
of all measured currents taken separately for each phase. The restrain current, on the other
hand, is considered as the greatest phase current in any line end and it is common for all three
phases.
IdMin
M12541-121 v6
This setting is a multiple of
IBase and must take into account the fundamental frequency line
charging current, and whether a power transformer is included in the protected zone or not.
The positive sequence line charging current is calculated according to equation
1MRK 505 343-UEN B
Section 6
Differential protection
125
Application manual
Содержание Relion 670 series
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