ABB REL650 Applications Manual page 149

1MRK 506 334-UUS A
Application manual
Resistive reach
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
specific zone to be coordinated to.
³ ×
RFltREvPG 1.2 RFPG
EQUATION1726 V1 EN
Phase-to-phase fault in forward direction
Reactive reach
The reach in reactive direction is determined by phase-to-ground reach setting X1. No
extra setting is required.
Resistive reach
In the same way as for phase-to-ground fault, the reach is automatically calculated based
on setting X1. The reach will be X1/tan(60°) =X1/√(3).
Fault resistance reach
The fault resistance reaches in forward direction RFItFwdPP, must cover RFPP
least 25% margin. RFPP
longest overreaching zone to be covered by FDPSPDIS (21), see figure 68. The minimum
recommended reach can be calculated according to equation 64.
³ ×
RFltFwdPP 1.25 RFPP
zm
EQUATION1318-ANSI V1 EN
where:
RFPP is the setting of the longest reach of the overreaching zones that must be covered by FDPSPDIS
Zm
(21).
Equation 64 modified is applicable also for the RFltRevPP as follows:
³ ×
1.25 RFPP
RFlt Re vPP
min
EQUATION2264-ANSI V1 EN
Equation 64 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 (21) characteristic angle is changed from 60 degrees to 90 degrees
(rotated 30° anti-clock wise).
ZmRv
is the setting of fault resistance for phase-to-phase fault for the
Zm
zmRv
Section 6
Impedance protection
63 the index ZmRv references the
(Equation 63)
with at
Zm
(Equation 64)
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