ABB RELION REX640 Technical Manual page 866

Section 4
Protection functions
860
Non-directional
Imp zone shape
Quadrilateral
Mho (circular)
Mho Dir line
Offset Dir line
Bullet (combi)
GUID-179A8D80-55DB-4CEF-9931-68C06F53CA0B V1 EN
Figure 464: Possible combinations of Directional mode Znx and Zone
characteristics settings. Pol. here means that the shape of the
characteristic is affected by the selected polarization method of mho
circle (Pol quantity zone = "Cross pol", "Pos. seq. volt.", "Self pol")
The directional lines are polarized with the set polarizing quantity of all impedance
measuring elements. In addition, the memory voltage that is based on positive-
sequence voltage substitute for the measured voltage with any impedance
measurement element polarization if the corresponding voltage drops too low.
DSTPDIS has separate and independent measurement elements for each fault loop in
the distance protection zone. In addition to the full scheme design, the separate
measuring elements are used for general fault detection and faulted phase selection.
DSTPDIS supports both fault detection dependent control of zone timers and zone-
dedicated phasewise timer control for maximum application flexibility.
The impedance measurement is always done the same way regardless of the zone
shape. The operation is based on the impedance mapping approach where the fault
loop impedance is first calculated and then compared to the zone boundaries. If
impedance is recognized within the operation zone, the corresponding operate output
is activated after the operate time has elapsed.
The impedance measurement is based on full-cycle DFT filtered current and voltage
phasors.
Directional mode Znx
Forward
X X
R
X X
R
X
X
R
X
X
R
X X
R
Pol. = polarization method affects (mho)zone shape
1MRS759142 C
Reverse
X
R R
Pol. Pol.
X
R R
Pol. Pol.
X
R R
X
R R
Pol. Pol.
X
R R
REX640
Technical Manual