ABB RET670 Applications Manual page 187

1MRK504116-UUS C
Application manual
Set the values of the corresponding zone (zero-sequence resistance and reactance)
equal to:
2
æ
X
m0
×
R R ç 1 ------------------------- -
= +
0E 0
2
è
R X
+
0 0
EQUATION561 V1 EN
2
æ
X
m0
×
------------------------- -
X = X ç 1 –
0E 0
2 2
è
R + X
0 0
EQUATION562 V1 EN
Setting of reach in resistive direction
Set the resistive reach R1 independently for each zone.
Set separately the expected fault resistance for phase-to-phase faults RFPP and for the
phase-to-ground faults RFPE for each zone. For each distance zone, set all remaining
reach setting parameters independently of each other.
The final reach in resistive direction for phase-to-ground fault loop measurement
automatically follows the values of the line-positive and zero-sequence resistance, and
at the end of the protected zone is equal to equation 86.
1
( )
= × + +
R 2 R1 R0 RFPE
3
IECEQUATION2303 V1 EN
é × +
2 X1 X0
j
=
loop arctan
ê
ë
× +
2 R1 R0
EQUATION2304 V1 EN
Setting of the resistive reach for the underreaching zone 1 should follow the condition
to minimize the risk for overreaching:
£ ×
RFPE 4.5 X1
IECEQUATION2305 V1 EN
The fault resistance for phase-to-phase faults is normally quite low, compared to the
fault resistance for phase-to-ground faults. To minimize the risk for overreaching, limit
the setting of the zone 1 reach in resistive direction for phase-to-phase loop
measurement to:
ö
÷
2
ø
ö
÷
ø
ù
ú
û
Section 3
IED application
(Equation 84)
(Equation 85)
(Equation 86)
(Equation 87)
(Equation 88)
181