Load Encroachment - ABB RET650 Technical Manual

1MRK 504 135-UEN A
7.3.6.1
Technical manual
The difference compared to the distance zone measuring function is in the
combination of measuring quantities (currents and voltages) for different types of
faults.
The current start condition STCNDLE is based on the following criteria:
1. Residual current criteria
2. Load encroachment characteristic
The STCNDLE output is non-directional.

Load encroachment

Each of the three 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 60. As illustrated, the resistive
blinders and the angle of the sectors are the same in all four quadrants.
ArgLd
ArgLd
RLd
IEC10000144 V2 EN
Figure 60: Characteristic of load encroachment function
The reach is limited by the minimum operation current and the distance measuring
zones.
Impedance protection
X
RLd
ArgLd
R
ArgLd
IEC10000144-1-en.vsd
Section 7
139