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X
0E
X
0
1
X
m0
2
R
0
2
X
0
2
+
--------------------------
–
è
ø
ç
÷
æ
ö
×
=
EQUATION562 V1 EN-US
(Equation 103)
7.1.3.7
Setting of reach in resistive direction
SEMOD168247-76 v2
Set the resistive reach independently for each zone, and separately for phase-to-phase (
R1PP),
and phase-to-earth loop (
R1PE) measurement.
Set separately the expected fault resistance for phase-to-phase faults (
R1PP) and for the
phase-to-earth faults (
RFPE) for each zone. Set all remaining reach setting parameters
independently of each other for each distance zone.
The final reach in 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
.
R
1
3
---
2 R1PE
×
R0PE
+
(
)
RFPE
+
=
EQUATION567 V1 EN-US
(Equation 104)
2 X1PE + X0
arctan
2 R1PE + R0
loop
j
é
ù
×
ê
ú
=
×
ê
ú
ë
û
EQUATION1457 V1 EN-US
(Equation 105)
Setting of the resistive reach for the underreaching zone1 must follow the following condition:
4.5
1
RFPE
X
£
×
EQUATION569 V2 EN-US
(Equation 106)
The fault resistance for phase-to-phase faults is normally quite low, compared to the fault
resistance for phase-to-earth faults. Limit the setting of the zone1 reach in resistive direction
for phase-to-phase loop measurement to:
3
1
RFPP
X
£ ×
EQUATION570 V2 EN-US
(Equation 107)
7.1.3.8
Load impedance limitation, without load encroachment function
SEMOD168247-91 v3
The following instructions is valid when the load encroachment function is not activated,
which is done by setting the parameter
Rld for the Phase Selector to its upper limit. If the load
encroachment function is to be used for all or some of the measuring zones, the load
limitation for those zones according to this chapter can be omitted. Check the maximum
permissible resistive reach for any zone to ensure that there is a sufficient setting margin
between the IED boundary and the minimum load impedance. The minimum load impedance
(Ω/phase) is calculated as:
1MRK 505 343-UEN B
Section 7
Impedance protection
187
Application manual
Summary of Contents for Relion 670 series
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