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2
0
1
1
1
1
1
3
N
Z
x Z
K
Z
Z
Z
+
= ×
+
-
×
IECEQUATION14016 V1 EN-US
(Equation 201)
For both case 1 and 2, the overreach would be much higher. For case 3, the function measures
the correct impedance.
The normal influence of infeeds is to be added to these influences of the mutual coupling for
setting of remote backup zones.
Setting of zone 3
GUID-3F20E209-A29C-4D16-84AB-F0594DC10AC0 v1
The reach of zone 3 is affected as well, but when zone is normally set with sufficient margin to
always overreach the remote line end, K
N3
for zone 3 can be set as for a single line, that is:
0
1
3
1
3
N
K
Z
Z
Z
=
-
IECEQUATION14020 V1 EN-US
(Equation 202)
Alternative 2: Different groups of setting parameters for different operating conditions of a
protected multi circuit line
GUID-DB67F163-289C-40C6-A850-074FFE61DEBC v2
Different group of setting parameters can be used for the three cases:
•
Parallel line switched off and earthed at both ends
•
Parallel line switched off and not earthed or earthed at only one end
•
Both lines in service.
With this method of setting the zero sequence compensation factor K
N
can for zone 1 and zone
2 be even better adapted for the real system conditions.
The table describes earth-fault compensation settings to be adopted for different groups.
Table 22: Different groups of settings
Group
Operation mode
Zone 1 and Zone 2
Zone 3 and Reverse Zone
Group1
Case 1: Parallel
line switched off
and earthed at
both ends
0
1
0
1
1
0
3
m
N
Nm
K
Z
Z
Z
K
Z
Z
=
-
-
0
1
1
3
N
Z
Z
K
Z
=
-
×
Group2
Case 2: Parallel
line switched off
and not earthed
or earthed at only
one end
0
1
1
3
N
Z
Z
K
Z
=
-
×
0
1
1
3
N
Z
Z
K
Z
=
-
×
Group3
Both lines in
service
0
1
1
3
N
Nm
K
Z
Z
K
Z
=
-
-
0
3
L
L
N
L
K
Z
Z
Z
=
-
For a discussion on other options of settings, refer to CIGRE SC34 report, WG-04 November
1991 “Application guide on protection of complex transmission network configuration”.
Section 7
1MRK 505 343-UEN B
Impedance protection
238
Application manual
Summary of Contents for Relion 670 series
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