ABB RELION RET670 - Load Encroachment

max
3
S
ILoad
VLmn
=
×
EQUATION1615-ANSI V1 EN-US (Equation 195)
where:
Smax is the maximal apparent power transfer during emergency conditions and
VLmn 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 LdAngle for the inclination of the load sector (see figure
149).
R
X
RLdFw
RLdRv
LdAngle
LdAngle
LdAngle
ANSI10000192_1_en.vsd
LdAngle
ANSI10000192 V1 EN-US
Figure 149: Load encroachment characteristic
The calculation of the apparent load impedance Z
load
and minimum load impedance
Z
loadmin
can be done according to equations:
min
max
3 I
V
Zload =
×
EQUATION1754-ANSI V1 EN-US (Equation 196)
1MRK 504 163-UUS A Section 8
Impedance protection
Transformer protection RET670 2.2 ANSI 319
Application manual