Basic Operation Characteristics - ABB Relion Technical Manual

1MRK 502 048-UUS A
7.2.6.3
Technical manual
jx
IEC09000172 V1 EN
Figure 67: Mho, offset mho characteristic
Zone 3 can be equipped with a load encroachment function which cuts off a section of the
characteristic when enabled. The function is activated by setting the parameter
LoadEnchModZ3 to Enable. Enabling of the load encroachment function increases the
possibility to detect high resistive faults without interfering with the load impedance. The
algorithm for the load encroachment is located in the Load encroachment (LEPDIS)
function, where the relevant settings can be found. Information about load encroachment
from LEPDIS function to zone measurement is sent via the input signal LDCND in binary
format.

Basic operation characteristics

Each impedance zone can be enabled and disabled by setting OpModeZx (where x is 1-3
depending on selected zone).
The zone reach for phase-to-phase fault is set individually in polar coordinates. The
impedance is set by the parameter ZxFwd and ZxRev and the corresponding angles by the
parameter ImpedanceAng. The setting ImpedanceAng is common for all three zones.
Section 7
Impedance protection
Mho, zone3
Mho, zone2
Mho, zone1
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