ABB Relion 670 series - Page 256

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