ABB REG670 - Basic Operation Characteristics

identification with load encroachment for mho function FMPSPDIS, where also the
relevant settings can be found. Information about the load encroachment from
FMPSPDIS to the zone measurement is given in binary format to the input signal
LDCND.
7.1.6.3 Basic operation characteristics
Each impedance zone can be switched On and Off by the setting parameter
Operation.
Each zone can be set to Non-directional, Forward or Reverse by setting the parameter
DirMode .
The mho characteristics can be classified into - Offset or Directional. The directional
mho characteristics can be set to Offset, Forward or Reverse by the setting parameter
DirMode. The offset mho characteristic can be set to Forward or Reverse or Non-
Directional by the setting parameter OffsetMhoDir.
The operation for phase-to-earth and phase-to-phase fault can be individually
switched On and Off by the setting parameter OpModePE and OpModePP.
For critical applications such as for lines with high SIRs as well as CVTs, it is possible
to improve the security by setting the parameter ReachMode to Underreach. In this
mode the reach for faults close to the zone reach is reduced by 20% and the filtering
is also introduced to increase the accuracy in the measuring. If the ReachMode is set to
Overreach no reduction of the reach is introduced and no extra filtering introduced.
The latter setting is recommended for overreaching pilot zone, zone 2 or zone 3
elements and reverse zone where overreaching on transients is not a major issue either
because of less likelihood of overreach with higher settings or the fact that these
elements do not initiate tripping unconditionally.
The offset Mho characteristic can be set in Non-directional, Forward or Reverse by
the setting parameter OffsetMhoDir. When Forward or Reverse is selected a
directional line is introduced. Information about the directional line is given from the
directional element and given to the measuring element as binary coded signal to the
input DIRCND.
When DirMode is set to offset and offsetMhoDir is set as Non-Directional, ZDMRDIR
does not have any effect on the measurement loop and operation of the function. When
DirMode is selected as Forward or Reverse, a directional line is introduced.
Information about the directional line is given from the directional element
(ZDMRDIR) and given to the measuring element as binary coded signal to the input
DIRCND.
The zone reach for phase-to-earth fault and phase-to-phase fault is set individually in
polar coordinates.
The impedance is set by the parameters ZPE and ZPP and the corresponding
arguments by the parameters ZAngPE and ZAngPP.
Section 7 1MRK502052-UEN B
Impedance protection
182
Technical manual