![background image](http://html1.mh-extra.com/html/abb/relion-670-series/relion-670-series_applications-manual_3052129241.webp)
x
is the ratio of distance to fault and length of the line
0
1
1
3
N
Z
Z
K
Z
=
-
×
IECEQUATION14005 V1 EN-US
(Equation 192)
K
Z
Z
Nm
m
=
⋅
0
1
3
IEC13000297 V1 EN-US
(Equation 193)
Case 2: Parallel line switched off and not earthed or earthed at one line end
Z
0m
A
B
Z<
Z<
IEC13000256-1-en.vsd
x
Ph-G
IEC13000256 V1 EN-US
Figure 146: Parallel line is out of service and not earthed
0
1
1
1
1
1
3
N
Z
x Z
K
Z
Z
Z
+
= ×
+
-
×
IECEQUATION14012 V1 EN-US
(Equation 194)
Case 3: Both lines in service
Z
0m
A
B
Z<
Z<
IEC13000257-1-en.vsd
x
Ph-G
IEC13000257 V1 EN-US
Figure 147: Class 1, parallel line in service
GUID-354B9143-D19E-4835-BCEA-737D7C5E02AA V1 EN-US
(Equation 195)
1MRK 505 343-UEN B
Section 7
Impedance protection
235
Application manual
Summary of Contents for Relion 670 series
Page 1: ...RELION 670 SERIES Line differential protection RED670 Version 2 1 IEC Application manual...
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