ABB Relion 670 series, Technical Manual

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7.2.6.4 Load encroachment
M13140-86 v6
Each of the six measuring loops has its own load encroachment characteristic based on the
corresponding loop impedance. The load encroachment functionality is always active, but can be
switched off by selecting a high setting.
The outline of the characteristic is presented in figure 86 . As illustrated, the resistive blinders are
set individually in forward and reverse direction while the angle of the sector is the same in all four
quadrants.
R
X
RLdFwd
RLdRev
LdAngle
LdAngle
LdAngle
LdAngle
en05000196_ansi.vsd
ANSI05000196 V1 EN-US
Figure 86: Characteristic of load encroachment function
The influence of load encroachment function on the operation characteristic is dependent on the
chosen operation mode of FDPSPDIS (21) function. When output signal PHSELZ is selected, the
characteristic for FDPSPDIS (21) (and also zone measurement depending on settings) will be
reduced by the load encroachment characteristic (see figure 87 , left illustration).
When output signal DLECND is selected, the operation characteristic will be as the right
illustration in figure 87 . The reach will in this case be limit by the minimum operation current and
the distance measuring zones.
Section 7 1MRK 502 066-UUS B
Impedance protection
206
Technical manual