ABB RET670 - Page 187

Set the values of the corresponding zone (zero-sequence resistance and reactance)
equal to:
R
0E
R
0
1
X
m0
2
R
0
2
X
0
2
+
--------------------------
+
è ø
ç ÷
æ ö
×=
EQUATION561 V1 EN (Equation 84)
X
0E
X
0
1
X
m0
2
R
0
2
X
0
2
+
--------------------------
–
è ø
ç ÷
æ ö
×=
EQUATION562 V1 EN (Equation 85)
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 (Equation 86)
2 X1 X0
arctan
2 R1 R0
loop j
× +
=
× +
é ù
ê ú
ë û
EQUATION2304 V1 EN (Equation 87)
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 (Equation 88)
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:
1MRK504116-UUS C Section 3
IED application
181
Application manual