R
X
Zm
RldRev
R
Zm
RLdFwd
ZL
ANSI05000495_2_en.vsd
Load impedance area in
forward direction
LdAngle
LdAngle
LdAngle
LdAngle
ANSI05000495 V2 EN
Figure 61: Load encroachment phenomena and shaped load encroachment
characteristic defined in Phase selection with load encroachment
function FDPSPDIS (21)
jX
R
Load
Load
Load
Load
jX
R
Load
Load
Load
Load
No
operation
en06000403.vsd
IEC06000403 V1 EN
Figure 62: Load encroachment phenomena and shaped load encroachment
characteristic
The load encroachment algorithm will increase the possibility to detect high fault
resistances, especially for phase to ground faults at remote line end. For example, in
quadrilateral characteristic, a given setting of the load angle LdAngle for phase selection
with load encroachment, the resistive blinder for the zone measurement can be expanded
according to the figure
61 given higher fault resistance coverage without risk for
unwanted operation due to load encroachment. This is valid in both directions. Again, for
example in mho characteristic, for a given setting of the load angle LdAngle (see
figure 63), the zone reach can be expanded according to the diagram on the right in
figure 62 given higher fault resistance coverage without risk for unwanted operation due
Section 6 1MRK 506 334-UUS A
Impedance protection
128
Application manual
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