5-140 L90 Line Current Differential System GE Multilin5.6 GROUPED ELEMENTS 5 SETTINGS5The ground mho distance function uses a dynamic 100% memory-polarized mho characteristic with additional reactance,directional, current, and phase selection supervising characteristics. The ground quadrilateral distance function is com-posed of a reactance characteristic, right and left blinders, and 100% memory-polarized directional, overcurrent, and phaseselection supervising characteristics.When set to non-directional, the mho function becomes an offset mho with the reverse reach controlled independently fromthe forward reach, and all the directional characteristics removed. When set to non-directional, the quadrilateral functionapplies a reactance line in the reverse direction instead of the directional comparators.The reactance supervision for the mho function uses the zero-sequence current for polarization. The reactance line of thequadrilateral function uses either zero-sequence or negative-sequence current as a polarizing quantity. The selection iscontrolled by a user setting and depends on the degree of non-homogeneity of the zero-sequence and negative-sequenceequivalent networks.The directional supervision uses memory voltage as polarizing quantity and both zero- and negative-sequence currents asoperating quantities.The phase selection supervision restrains the ground elements during double-line-to-ground faults as they – by principlesof distance relaying – may be inaccurate in such conditions. Ground distance zones 1 and higher apply additional zero-sequence directional supervision. See chapter 8 for additional details.Each ground distance zone is configured individually through its own setting menu. All of the settings can be independentlymodified for each of the zones except:1. The SIGNAL SOURCE setting (common for both phase and ground elements for all zones as entered under the SETTINGSÖØ GROUPED ELEMENTS Ö SETTING GROUP 1(6) ÖØ DISTANCE menu).2. The MEMORY DURATION setting (common for both phase and ground elements for all zones as entered under the SET-TINGS ÖØ GROUPED ELEMENTS Ö SETTING GROUP 1(6) ÖØ DISTANCE menu).The common distance settings noted at the start of this section must be properly chosen for correct operation of the grounddistance elements.Although all ground distance zones can be used as either instantaneous elements (pickup [PKP ] and dropout [DPO ] Flex-Logic™ signals) or time-delayed elements (operate [ OP ] FlexLogic™ signals), only zone 1 is intended for the instantaneousunder-reaching tripping mode.Ensure that the PHASE VT SECONDARY VOLTAGE (see the SETTINGS ÖØ SYSTEM SETUP Ö AC INPUTS ÖØ VOLTAGEBANK menu) is set correctly to prevent improper operation of associated memory action.• GND DIST Z1 DIR: All ground distance zones are reversible. The forward direction is defined by the GND DIST Z1 RCAsetting and the reverse direction is shifted by 180° from that angle. The non-directional zone spans between the for-ward reach impedance defined by the GND DIST Z1 REACH and GND DIST Z1 RCA settings, and the reverse reach imped-ance defined by the GND DIST Z1 REV REACH and GND DIST Z1 REV REACH RCA settings.• GND DIST Z1 SHAPE: This setting selects the shape of the ground distance characteristic between the mho andquadrilateral characteristics. The selection is available on a per-zone basis.MESSAGE GND DIST Z1 POS-SEQSUPV RESTR: 0.050 puRange: 0.000 to 0.500 pu in steps of 0.001MESSAGE GND DIST Z1 VOLTLEVEL: 0.000 puRange: 0.000 to 5.000 pu in steps of 0.001MESSAGE GND DIST Z1DELAY: 0.000 sRange: 0.000 to 65.535 s in steps of 0.001MESSAGE GND DIST Z1 BLK:OffRange: FlexLogic™ operandMESSAGE GND DIST Z1TARGET: Self-ResetRange: Self-Rest, Latched, DisabledMESSAGE GND DIST Z1EVENTS: DisabledRange: Disabled, EnabledWARNING
