ABB RELION RET670 - Resistive Reach with Load Encroachment Characteristic

8.10.4.1 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 LdAngle, the blinder RLdFwd in forward direction and blinder
RLdRev in reverse direction, as shown in figure
169.
R
X
RLdFwd
RLdRev
LdAngle
LdAngle
LdAngle
en05000226_ansi.vsd
LdAngle
ANSI05000226 V1 EN-US
Figure 169: Load encroachment characteristic
The load angle LdAngle 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, RLdFwd, can be calculated according to
equation
249.
= ×
2
min
0.8
exp max
RLdFwd
P
V
where:
P exp max is the maximum exporting active power
V min is the minimum voltage for which the Pexp max occurs
0.8 is a security factor to ensure that the setting of
RLdFwd can be lesser than the calculated
minimal resistive load.
Section 8 1MRK 504 163-UUS A
Impedance protection
358 Transformer protection RET670 2.2 ANSI
Application manual