R
0E
R
0
1
X
m0
2
R
0
2
X
0
2
+
--------------------------
+
è ø
ç ÷
æ ö
×=
EQUATION561 V1 EN-US (Equation 61)
X
0E
X
0
1
X
m0
2
R
0
2
X
0
2
+
--------------------------
–
è ø
ç ÷
æ ö
×=
EQUATION562 V1 EN-US (Equation 62)
7.1.3.6 Setting the reach with respect to load
GUID-ED84BDE6-16CD-45ED-A45D-5CFB828A9040 v6
Set separately the expected fault resistance for phase-to-phase faults RFPPZx and
for the phase-to-earth faults RFPEZx for each zone. For each distance zone, set all
remaining reach setting parameters independently of each other.
The final reach in the resistive direction for phase-to-earth 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 63.
1
R 2 R1Zx R0Zx RFPEZx
3
IECEQUATION2303 V2 EN-US (Equation 63)
2X1Zx X0Zx
arctan
2 R1Zx R0Zx
loop
EQUATION2304 V2 EN-US (Equation 64)
Setting of the resistive reach for the underreaching zone 1 should follow the
condition to minimize the risk for overreaching:
IECEQUATION2305 V2 EN-US (Equation 65)
The fault resistance for phase-to-phase faults is normally quite low compared to the
fault resistance for phase-to-earth faults. To minimize the risk for overreaching,
limit the setting of the zone1 reach in the resistive direction for phase-to-phase loop
measurement based on equation 66.
IECEQUATION2306 V3 EN-US (Equation 66)
The setting XLd is primarily there to define the border between what is considered
a fault and what is just normal operation. See figure
63 In this context, the main
examples of normal operation are reactive load from reactive power compensation
equipment or the capacitive charging of a long high-voltage power line. XLd needs
Section 7 1MRK 505 393-UEN B
Impedance protection
126 Line differential protection RED650 2.2 IEC
Application manual
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