5-240 L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUALGROUPED ELEMENTS CHAPTER 5: SETTINGS5GND DIST Z1 DIR RCA — Selects the characteristic angle (or maximum torque angle) of the directional supervising function. Ifthe mho shape is applied, the directional function is an extra supervising function, as the dynamic mho characteristic itselfis a directional one. In conjunction with the quadrilateral shape selection, this setting defines the only directional functionbuilt into the ground distance element. The directional function uses memory voltage for polarization.GND DIST Z1 DIR COMP LIMIT — This setting selects the comparator limit angle for the directional supervising function.GND DIST Z1 QUAD RGT BLD — This setting defines the right blinder position of the quadrilateral characteristic along theresistive axis of the impedance plane (see the Quadrilateral Distance Characteristic figure). The angular position of theblinder is adjustable with the use of the GND DIST Z1 QUAD RGT BLD RCA setting. This setting applies only to the quadrilateralcharacteristic; set it with consideration to the maximum load current and required resistive coverage.GND DIST Z1 QUAD RGT BLD RCA — This setting defines the angular position of the right blinder of the quadrilateralcharacteristic (see the Quadrilateral Distance Characteristic figure).GND DIST Z1 QUAD LFT BLD — This setting defines the left blinder position of the quadrilateral characteristic along theresistive axis of the impedance plane (see the Quadrilateral Distance Characteristic figure). The angular position of theblinder is adjustable with the use of the GND DIST Z1 QUAD LFT BLD RCA setting. This setting applies only to the quadrilateralcharacteristic; set it with consideration to the maximum load current.GND DIST Z1 QUAD LFT BLD RCA — This setting defines the angular position of the left blinder of the quadrilateralcharacteristic (see the Quadrilateral Distance Characteristic figure).GND DIST Z1 SUPV — The ground distance elements are supervised by the magnitude of the neutral (3I_0) current. Set thecurrent supervision pickup to be less than the minimum 3I_0 current for the end of the zone fault, taking into account therequired fault resistance coverage to prevent maloperation due to VT fuse failure. Settings less than 0.2 pu are notrecommended, so apply them with caution. To enhance ground distance security against spurious neutral current duringswitch-off transients, three-phase faults, and phase-to-phase faults, a positive-sequence current restraint of 5% is appliedto the neutral current supervision magnitude. Set this setting at least three times the CURRENT CUTOFF LEVEL settingspecified in the PRODUCT SETUP DISPLAY PROPERTIES menu.GND DIST Z1 VOLT LEVEL — This setting is relevant for applications on series-compensated lines, or in general, if seriescapacitors are located between the relaying point and a point for which the zone shall not overreach. For plain (non-compensated) lines, set it to zero. Otherwise, the setting is entered in per unit of the VT bank configured under theDISTANCE SOURCE. Effectively, this setting facilitates dynamic current-based reach reduction. In non-directionalapplications (GND DIST Z1 DIR set to “Non-directional”), this setting applies only to the forward reach of the non-directionalzone. See the Application of Settings chapter for details and information on calculating this setting value for applicationson series compensated lines.GND DIST Z1 DELAY — This setting enables the user to delay operation of the distance elements and implement a steppeddistance backup protection. The distance element timer applies a short drop-out delay to cope with faults located close tothe boundary of the zone when small oscillations in the voltages or currents can inadvertently reset the timer.GND DIST Z1 BLK — This setting enables the user to select a FlexLogic operand to block the given ground distance element.VT fuse fail detection is one of the applications for this setting.
