Four Step Residual Overcurrent Protection Ef4Ptoc - ABB Relion 650 Series Applications Manual

Section 6
Current protection
~
IEC09000025 V1 EN-US
Figure 35: Two parallel lines. Influence from parallel line to the through fault current: I
The minimum theoretical current setting (Imin) will in this case be:
³
I m in
EQUATION287 V1 EN-US
Where:
I and I
fA
Considering the safety margins mentioned previously, the minimum setting (Is) is:
I = 1.3 × I
s
EQUATION288 V3 EN-US
Transformer inrush current shall be considered.
The setting of the protection is set as a percentage of the base current (
Operation : set the protection to On or Off .
IN>> : Set operate current in % of IBase .
StValMult : The operate current can be changed by activation of the binary input ENMULT to
the set factor
6.4

Four step residual overcurrent protection EF4PTOC

76
A C
Z
A
Fault
I
M
IED
, ,
M A X I I I
( )
fA fB M
have been described for the single line case.
fB
min
StValMult .
Line 1
B
Z
L1
Z
B
M
Z
L2
Line 2
~
IEC09000025-1-en.vsd
IBase ).
Application manual
1MRK 505 355-UEN A
M
(Equation 23)
(Equation 24)
IP14509-1 v7