ABB Relion 670 Series Applications Manual page 152

Section 8
Current protection
~
ANSI09000025 V2 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 M A X I
EQUATION287 V1 EN-US
Where:
I and I
fA fB
Considering the safety margins mentioned previously, the minimum setting (Is) is:
I = 1.3 × I
s
EQUATION288 V3 EN-US
The IED setting value
IN>> is given by the formula:
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 Enabled or Disabled .
Pickup : 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>>Max and IN>>Min , the closest of the limits to IN>> is used by the function. If IN>>Max is
smaller than
146
A C
Z
A
Fault
IED
, ,
( I I )
fA fB M
have been described for the single line case.
min
IN>> is given in percent of the primary base current value, IBase. The value

( I IBase ) 100
s
IN>>Min , the limits are swapped.
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Line 1
B
Z
L1
Z
M
Z
L2
I
M
Line 2
~
B
ANSI09000025_2_en.vsd
IBase ).
IN>> setting. If IN>> is set outside
1MRK 511 401-UUS F
M
(Equation 38)
(Equation 39)
(Equation 40)
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