ABB Relion 670 Series Technical Reference Manual page 256

Section 6
Impedance protection
250
where
V is the polarizing voltage (memorized VA for Phase A-to- ground fault)
pol
Z is the loop impedance, which in general terms can be expressed as
loop
=
Z +ZN Z
1
EQUATION1799 V1 EN
where
Z is the positive sequence impedance of the line (Ohm/phase)
1
KN is the zero-sequence compensator factor
The angle β between the Vcomp and the polarize voltage Vpol for a A-to-ground fault is
(
é
b = - + ×
arg V I IN KN ZPE
ë
A A
EQUATION1592 V1 EN
where
V is the phase voltage in faulty phase A
A
I is the phase current in faulty phase A
A
I is the phase current in faulty phase A
A
IN is the zero-sequence current in faulty phase A (3I0)
Z0-Z1
KN
×
3 Z1
EQUATION1593 V1 EN
EQUATION1594 V1 EN
the setting parameter for the zero sequence compensation consisting of the
magnitude
V is the 100% of positive sequence memorized voltage V
pol
V is the 100% of positive sequence memorized voltage V
pol
( )
× +
1 KN
1
)
ù
× -
arg(Vpol)
û
KN and the angle KNAng .
1MRK505222-UUS C
(Equation 37)
(Equation 38)
A
A
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