7.2.3.2
Resistive reach with load encroachment characteristic
M13142-312 v4
The procedure for calculating the settings for the load encroachment consist basically to
define the load angle
ArgLd, the blinder RLdFw in forward direction and blinder RLdRv in
reverse direction, as shown in figure
R
X
RLdFw
RLdRv
ArgLd
ArgLd
ArgLd
ArgLd
IEC09000050-1-en.vsd
IEC09000050 V1 EN-US
Figure 121: Load encroachment characteristic
The load angle
ArgLd is the same in forward and reverse direction, so it could be suitable to
begin to calculate the setting for that parameter. Set the parameter to the maximum possible
load angle at maximum active load. A value bigger than 20° must be used.
The blinder in forward direction,
RLdFw, can be calculated according to equation
2
min
0.8
exp max
U
RLdFw
P
=
×
where:
Pexp max is the maximum exporting active power
Umin
is the minimum voltage for which the Pexp max occurs
0.8
is a security factor to ensure that the setting of
RLdFw can be lesser than the calculated minimal
resistive load.
The resistive boundary
RLdRv for load encroachment characteristic in reverse direction can be
calculated in the same way as
RLdFw, but use maximum importing power that might occur
instead of maximum exporting power and the relevant Umin voltage for this condition.
7.2.3.3
Minimum operate currents
M13142-334 v5
FDPSPDIShas two current setting parameters which blocks the respective phase-to-earth loop
and phase-to-phase loop if the RMS value of the phase current (ILn) and phase difference
current (ILmILn) is below the settable threshold.
The threshold to activate the phase selector for phase-to-earth (
IMinOpPE) is set to securely
detect a single phase-to-earth fault at the furthest reach of the phase selection. It is
recommended to set
IMinOpPP to double value of IMinOpPE.
The threshold for opening the measuring loop for phase-to-earth fault (
INReleasePE) is set
securely detect single line-to-earth fault at remote end on the protected line. It is
recommended to set
INBlockPP to double value of INReleasePE.
Section 7
1MRK 505 343-UEN B
Impedance protection
196
Application manual
Summary of Contents for Relion 670 series
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