ABB Relion 670 series, Technical Manual

Page: 356 / 1432

X
R
X
R
OpModePP/PEZx = Mho
Zone 1, Zone 2 and
DirModeZ3-5 = Forward
OpModePP/PEZx = Mho
Zone RV and
DirModeZ3-5 = Reverse
X
R
OpModePP/PEZx = Mho
Only Zone 3-5
DirModeZ3-5 = Non-directional
X
R
OpModePP/PEZx = Offset
Zone 1, Zone 2 and
DirModeZ3-5 = Forward
OpModePP/PEZx = Offset
Zone RV and
DirModeZ3-5 = Reverse
X
R
OpModePP/PEZx = Offset
Only Zone 3-5
DirModeZ3-5 = Non-directional
X
R
IEC15000065.vsdx
IEC15000065 V1 EN-US
Figure 177: Mho characteristics
For each zone, the impedance is set in cartesian coordinates (resistance and reactance) which is
the same as for quadrilateral characteristic.
ZMFCPDIS function uses separate sets of reach settings in forward and reverse directions for
phase-to-earth fault and phase-to-phase fault. These settings are
R1FwPPZx, X1FwPPZx,
X1RvPPZx, R1FwPEZx, X1FwPEZx, X1RvPEZx, R0FWPEZx, X0FwPPZx (x=1-5 or RV). Thus, the center
of the
Non-directional offset mho circle can be arbitrary located in the circle (figure
177 ).
Note that the reverse ZoneRV, as well as any of zones 3-5, that are set to
DirModeZx=Reverse will
get their operating impedances inverted (rotated 180 degrees) internally in order to make use of
the main settings, which are the settings designated ‘Fw’. Therefore, a reverse zone will have its
Fw-settings ( R1FwPPZRV, X1FwPEZ3, and so on) applied in the third quadrant, that is, towards the
busbar instead of the line.
In
Non-directional mode, for both Mho and Quad, the reach settings are equal to Forward mode in
this respect. The ‘Fw’ settings apply in the first quadrant and the ‘Rv’ settings apply in the third
quadrant.
Section 7 1MRK 502 066-UUS B
Impedance protection
350
Technical manual