Resistive reach
M13142-156 v4
The resistive reach in reverse direction must be set longer than the longest reverse
zones. In blocking schemes it must be set longer than the overreaching zone at
remote end that is used in the communication scheme. In equation
97 the index
ZmRv references the specific zone to be coordinated to.
min ZmRv
RFRvPE 1.2 RFPE³ ×
EQUATION1316 V1 EN-US (Equation 97)
Phase-to-phase fault in forward direction
M13142-168 v2
Reactive reach
M13142-170 v3
The reach in reactive direction is determined by phase-to-earth reach setting X1.
No extra setting is required.
Resistive reach
M13142-173 v4
In the same way as for phase-to-earth fault, the reach is automatically calculated
based on setting X1. The reach will be X1/tan(60°) =X1/√(3).
Fault resistance reach
M13142-176 v7
The fault resistance reaches in forward direction RFFwPP, must cover RFPP
Zm
with at least 25% margin. RFPP
Zm
is the setting of fault resistance for phase-to-
phase fault for the longest overreaching zone to be covered by FDPSPDIS, see
Figure
105. The minimum recommended reach can be calculated according to
equation 98.
EQUATION1318 V3 EN-US (Equation 98)
where:
RFPP
Zm
is the setting of the longest reach of the overreaching zones that must be covered by
FDPSPDIS .
Equation 98 modified is applicable also for the RFRvPP as follows:
min
1.25
zmRv
RFRvPP RFPP³ ×
EQUATION2264 V1 EN-US (Equation 99)
Equation 98 is also valid for three-phase fault. The proposed margin of 25% will
cater for the risk of cut off of the zone measuring characteristic that might occur at
three-phase fault when FDPSPDIS characteristic angle is changed from 60 degrees
to 90 degrees (rotated 30° anti-clock wise).
Section 8 1MRK 506 369-UEN B
Impedance protection
206 Line distance protection REL670 2.2 IEC
Application manual
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