ABB REC650 Applications Manual page 111

1MRK 511 286-UUS A
Application manual
A
Z
~
A
ANSI09000025 V2 EN
Figure 42: Two parallel lines. Influence from parallel line to the through fault current:
I
M
The minimum theoretical current setting (Imin) will in this case be:
³ , ,
I m in M A X I ( I I )
fA fB M
EQUATION287 V1 EN
Where:
I and I have been described for the single line case.
fA fB
Considering the safety margins mentioned previously, the minimum setting (Is) is:
I ³
1.3.I
s m in
EQUATION288 V2 EN
Transformer inrush current shall be considered.
The setting of the protection is set as a percentage of the base current (IBase).
Operation: set the protection to Enabled or Disabled.
Pickup: Set operate current in % of IBase. IBase is a global parameter valid for all
functions in the IED.
Line 1
C
Z
L1
M
Fault
Z
L2
I
M
IED
Line 2
Section 6
Current protection
B
Z
~
B
ANSI09000025_2_en.vsd
(Equation 36)
(Equation 37)
105