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Table 2.26-2 Setting [FL_DIR] corresponding to the setting of OC and other relay elements
Direction of the relay (OC element etc)
Setting the unit of length/distance
(iv)
As shown in Figure 2.26-2, the fault location is displayed in kilometers when km is set for
scheme switch [FL_Unit]. On the other hand, if the preference is to display the fault location
in miles, the user should set mile for the scheme switch [FL_Unit]. In the case that km is set
using scheme switch [FL_Unit], the user can apply a value to set the line length using
[FL_Line_km]. In the case that mile is selected in setting [FL_Unit], the value of setting
[FL_Line_mile] is used to apply the line length value.
Setting of FL execution
(v)
The FL computation is ready when On is set for setting [FL_EN].
Computation for overreaching
(vi)
If the user wishes to obtain the result of the FL computation when the fault occurs beyond the
boundary defined with the setting [FL_Line_km] or [FL_Line_mile], the result can be displayed
when On is set for setting [FL_ALL_Zone]. Note that the fault location will be displayed by On
being set for the [FL_ALL_Zone], but the result for overreaching cannot be guaranteed in the
FL computation; thereby, it must be taken carefully.
Compensation for earth faults on parallel lines
(vii)
When applied to parallel lines the FL computation for earth faults is compensated by
introducing the residual current (3I 0 ) from the adjacent line. The residual current is used to
compensate the input current when the earth fault occurs. It is also possible to compensate the
input current using the source-impedance if the residual current on the adjacent line is not
available. Note that this form of compensation is only used when I 0m cannot be introduced
from the parallel line.
We recommend that the input current be compensated using the residual current from
the adjacent line; compensation using the residual current improves the accuracy of the FL
computation. (Set scheme switch [FL-Z0B] to Off)
If the residual current of the adjacent line is not available, the user should set the scheme
switch [FL-Z0B] On so that the FL result is compensated using the zero-sequence source-
impedances for an earth fault. Table 2.26-3 summarizes the compensation methods provided
Forward
Reverse
Non-dir
- 302 -
Scheme switch [FL_DIR]
Forward
Reverse
Forward / Reverse
6F2T0207 (0.01)
GRE200 (5,6)
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