ABB REL670 2.2 IEC - Load Encroachment

IMaxLoad =1.2 ILoad
EQUATION1614 V2 EN-US (Equation 222)
where:
1.2 is the security margin against the load current and
ILoad is the maximal load current during emergency conditions.
The current ILoad can be defined according to equation 223.
max
3
S
ILoad
ULmn
=
×
EQUATION1615 V1 EN-US (Equation 223)
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.
8.8.3.1 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 145).
R
X
RLdFw
RLdRv
ARGLd
ARGLd
ARGLd
ARGLd
en05000226.vsd
IEC05000226 V1 EN-US
Figure 145: Load encroachment characteristic
The calculation of the apparent load impedance Z
load
and minimum load
impedance Z
loadmin
can be done according to equations:
Section 8 1MRK 506 369-UEN B
Impedance protection
288 Line distance protection REL670 2.2 IEC
Application manual