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max
3
S
ILoad
ULmn
=
×
EQUATION1615 V1 EN-US
(Equation 246)
where:
Smax
is the maximal apparent power transfer during emergency conditions and
ULmn
is the phase-to-phase voltage during the emergency conditions at the IED location.
7.8.3.1
Load encroachment
SEMOD154782-39 v4
The load encroachment function has two setting parameters,
RLd for the load resistance and
ArgLd for the inclination of the load sector (see figure
R
X
RLdFw
RLdRv
ARGLd
ARGLd
ARGLd
ARGLd
en05000226.vsd
IEC05000226 V1 EN-US
Figure 161: Load encroachment characteristic
The calculation of the apparent load impedance Z
load
and minimum load impedance Z
loadmin
can be done according to equations:
Z
load
U
min
3 I
max
×
----------------------
=
EQUATION574 V1 EN-US
(Equation 247)
Z
loadmin
U
2
S
-------
=
EQUATION571 V1 EN-US
(Equation 248)
Where:
U
is the minimum phase-to-phase voltage in kV
S
is the maximum apparent power in MVA.
The load angle
ArgLd can be derived according to equation
1MRK 505 343-UEN B
Section 7
Impedance protection
265
Application manual
Summary of Contents for Relion 670 series
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