ABB Relion 670 Series Applications Manual page 148

Section 8
Current protection
~
IEC09000025 V1 EN-US
Figure 67: 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
The IED setting value
value for

IN
IECEQUATION17003 V1 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 IB .
IN>>Max and IN>>Min should only be changed if remote setting of operation current level,
IN>> , is used. The limits are used for decreasing the used range of the IN>> setting. If IN>> is
set outside
IN>>Max is smaller than IN>>Min , the limits are swapped.
StValMult : The set operate current can be changed by activation of the binary input ENMULT to
the set factor
142
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
IN>> is given in percent of the primary base current value, IBase. The
IN>> is given by the formula:

( I IBase ) 100
s
IN>>Max and IN>>Min , the closest of the limits to IN>> is used by the function. If
StValMult .
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B
Z
L1
Z
B
M
Z
L2
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1MRK 511 401-UEN Rev. K
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IEC09000025-1-en.vsd
IBase ).
Bay control REC670
Application manual
M
(Equation 38)
(Equation 39)
(Equation 40)