Operation Principle - ABB Relion Technical Manual

1MRK 502 048-UUS A
Table 81: LEPDIS Non group settings (basic)
Name Values (Range)
GlobalBaseSel 1 - 6
7.5.6
7.5.6.1
Technical manual
Unit Step
- 1

Operation principle

The basic impedance algorithm for the operation of Load encroachment LEPDIS is the
same as for the distance zone measuring function. LEPDIS includes three impedance
measuring loops intended for phase-to-phase as well as for three-phase faults.
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 pickup condition DLECND is based on the following criteria:
1. Residual current criteria
2. Load encroachment characteristic
The DLECND 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 85. As illustrated, the resistive
blinders and the angle of the sectors are the same in all four quadrants.
Default Description
1 Selection of one of the Global Base Value
groups
Section 7
Impedance protection
189