ABB Relion 670 series - Page 317

apparent impedances at phase-to-phase faults follow equation 4 (example for a phase A
to phase B fault).
=
V
A
- V
B
Z
app
I
A
- I
B
EQUATION1545 V1 EN (Equation 54)
Here V and I represent the corresponding voltage and current phasors in the respective
phase Ln (n = 1, 2, 3)
The ground return compensation applies in a conventional manner to phase-to-ground
faults (example for a phase A to ground fault) according to equation 5.
=
+ ×
app
N
V _ A
Z
I _ A I KN
EQUATION1546 V1 EN (Equation 55)
Where:
V_A, I_A and IN are the phase voltage, phase current and residual current present to the IED
KN is defined as:
Z0 Z1
KN
3 Z1
-
=
×
EQUATION-2105 V1 EN
0 0 0Z R jX= +
EQUATION2106 V1 EN
1 1 1Z R jX= +
EQUATION2107 V1 EN
Where
R0 is setting of the resistive zero sequence reach
X0 is setting of the reactive zero sequence reach
R1 is setting of the resistive positive sequence reach
X1 is setting of the reactive positive sequence reach
Here IN is a phasor of the residual current in IED point. This results in the same reach
along the line for all types of faults.
1MRK505222-UUS C Section 6
Impedance protection
311
Technical reference manual