Overview
Although all “Ground distance” zones can be used as either instantaneous elements or time-delayed elements, only zone 1 is intended for the instantaneous underreaching tripping mode. The “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 composed of a reactance characteristic, right and left blinders, and 100% memory-polarized directional, overcurrent, and phase selection supervising characteristics.
For more detailed information on “Ground distance” element, refer to GE, Universal Relay (UR) family of products, Version 8.0x manuals.
To view other supported elements, click here.
Setting Parameters
Modbus memory map for Setting parameters
| Products | Hex address | Register name | Range | Units | Step | Format | Default |
| D30, D60, L60, L90, T60 | 4887 | Ground Distance Zone 1 Function | 0 to 1 | — | 1 | F102 | 0 (Disabled) |
| " | 4888 | Ground Distance Zone 1 Current Supervision | 0.05 to 30 | pu | 0.001 | F001 | 200 |
| " | 4889 | Ground Distance Zone 1 Reach | 0.02 to 500 | ohms | 0.01 | F001 | 200 |
| " | 488A | Ground Distance Zone 1 Direction | 0 to 2 | — | 1 | F154 | 0 (Forward) |
| " | 488B | Ground Distance Zone 1 Comparator Limit | 30 to 90 | degrees | 1 | F001 | 90 |
| " | 488C | Ground Distance Zone 1 Delay | 0 to 65.535 | s | 0.001 | F001 | 0 |
| " | 488D | Ground Distance Zone 1 Block | 0 to 4294967295 | — | 1 | F300 | 0 |
| " | 488F | Ground Distance Zone 1 Target | 0 to 2 | — | 1 | F109 | 0 (Self-reset) |
| " | 4890 | Ground Distance Zone 1 Events | 0 to 1 | — | 1 | F102 | 0 (Disabled) |
| " | 4891 | Ground Distance Zone 1 Shape | 0 to 1 | — | 1 | F120 | 0 (Mho) |
| " | 4892 | Ground Distance Zone 1 Z0 Z1 Magnitude | 0 to 10 | — | 0.01 | F001 | 270 |
| " | 4893 | Ground Distance Zone 1 Z0 Z1 Angle | -90 to 90 | degrees | 1 | F002 | 0 |
| " | 4894 | Ground Distance Zone 1 RCA | 30 to 90 | degrees | 1 | F001 | 85 |
| " | 4895 | Ground Distance Zone 1 DIR RCA | 30 to 90 | degrees | 1 | F001 | 85 |
| " | 4896 | Ground Distance Zone 1 DIR Comp Limit | 30 to 90 | degrees | 1 | F001 | 90 |
| " | 4897 | Ground Distance Zone 1 Quad Right Blinder | 0.02 to 500 | ohms | 0.01 | F001 | 1000 |
| " | 4898 | Ground Distance Zone 1 Quad Right Blinder RCA | 60 to 90 | degrees | 1 | F001 | 85 |
| " | 4899 | Ground Distance Zone 1 Quad Left Blinder | 0.02 to 500 | ohms | 0.01 | F001 | 1000 |
| " | 489A | Ground Distance Zone 1 Quad Left Blinder RCA | 60 to 90 | degrees | 1 | F001 | 85 |
| " | 489B | Ground Distance Zone 1 Z0M Z1 Magnitude | 0 to 7 | — | 0.01 | F001 | 0 |
| " | 489C | Ground Distance Zone 1 Z0M Z1 Angle | -90 to 90 | degrees | 1 | F002 | 0 |
| " | 489D | Ground Distance Zone 1 Voltage Level | 0 to 5 | pu | 0.001 | F001 | 0 |
| " | 489E | Ground Distance Zone 1 Non- Homogeneous Angle | -40 to 40 | degrees | 0.1 | F002 | 0 |
| " | 489F | Ground Distance Zone 1 POL Current | 0 to 1 | — | 1 | F521 | 0 (Zero-seq) |
| " | 48A0 | Ground Distance Zone 1 Reverse Reach | 0.02 to 500 | ohms | 0.01 | F001 | 200 |
| " | 48A1 | Ground Distance Zone 1 Reverse Reach RCA | 30 to 90 | degrees | 1 | F001 | 85 |
| " | 48A2 | Reserved (7 items) | 0 to 65535 | — | 1 | F001 | 0 |
| " | 48A9 | …Repeated for Ground Distance Zone 2 | |||||
| " | 48CB | …Repeated for Ground Distance Zone 3 | |||||
| D30, D60, L90, T60 | 48ED | …Repeated for Ground Distance Zone 4 | |||||
| " | 490F | …Repeated for Ground Distance Zone 5 | |||||
| D60, L90 | 4931 | …Repeated for Ground Distance Zone 6 |
| F102 | 0 = Disabled, 1 = Enabled | ||||||
| F109 | 0 = Self-reset, 1 = Latched, 2 = Disabled | ||||||
| F120 | 0 = Mho, 1 = Quad, Fixed at Mho in G60 | ||||||
| F154 | 0 = Forward, 1 = Reverse, 2 = Non-Directional | ||||||
| F300 | 0 : Off (This is boolean FALSE value), 1 : On (This is boolean TRUE value) | ||||||
| F521 | 0 = Zero-Sequence, 1 = Negative-Sequence | ||||||
Logics & highlights
Directional quadrilateral ground distance characteristic
Non-directional quadrilateral ground distance characteristic
Ground distance zone 1 OP scheme
Ground distance zone 2 OP scheme
Ground distance zone 1 pickup logic
Ground distance zones 2 and higher pickup logic
Ground directional supervision logic
Definition of Setting Parameters
GND DIST Z1 DIR — All ground distance zones are reversible. The forward direction is defined by the GND DIST Z1 RCA setting and the reverse direction is shifted by 180° from that angle. The non-directional zone spans between the forward reach impedance defined by the GND DIST Z1 REACH and GND DIST Z1 RCA settings, and the reverse reach impedance 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 and quadrilateral characteristics. The selection is available on a per-zone basis.
The figures show the directional and non-directional quadrilateral ground distance characteristics. The directional and non-directional mho ground distance characteristics are the same as those shown for the phase distance element in the previous section.
GND DIST Z1 Z0/Z1 MAG — This setting specifies the ratio between the zero-sequence and positive-sequence impedance required for zero-sequence compensation of the ground distance elements. This setting is available on a per-zone basis, enabling precise settings for tapped, non-homogeneous, and series compensated lines.
GND DIST Z1 Z0/Z1 ANG — This setting specifies the angle difference between the zero-sequence and positive-sequence impedance required for zero-sequence compensation of the ground distance elements. The entered value is the zero sequence impedance angle minus the positive-sequence impedance angle. This setting is available on a per-zone basis, enabling precise values for tapped, non-homologous, and series compensated lines.
GND DIST Z1 ZOM/Z1 MAG — The ground distance elements can be programmed to apply compensation for the zero sequence mutual coupling between parallel lines. If this compensation is required, the ground current from the parallel line (3I_0) measured in the direction of the zone being compensated must be connected to the ground input CT of the CT bank configured under the DISTANCE SOURCE. This setting specifies the ratio between the magnitudes of the mutual zero sequence impedance between the lines and the positive-sequence impedance of the protected line. Set this setting to zero if the compensation is not to be performed. Note that internally the mutual coupling compensation is applied only if 3I_0>1.22*IG to ensure that no mutual coupling compensation is applied when the fault is on the parallel line. Mutual coupling compensation is applied when distance source is assigned with 8F or 8L type DSP module only and when the ratio of the protected line ground current to parallel line ground current is greater than 1.22.
GND DIST Z1 ZOM/Z1 ANG — This setting specifies the angle difference between the mutual zero-sequence impedance between the lines and the positive-sequence impedance of the protected line.
GND DIST Z1 REACH — This setting defines the reach of the zone for the forward and reverse applications. In non-directional applications, this setting defines the forward reach of the zone. The reverse reach impedance in non-directional applications is set independently. The angle of the reach impedance is entered as the GND DIST Z1 RCA setting. The reach impedance is entered in secondary ohms.
To achieve specified operating speed of distance elements, the relay internally calculates source to line impedance ratio (SIR) from fault phasors. In these calculations, line impedance is estimated based on the zone 1 reach setting. Therefore, in order to calculate the SIR value properly and to maintain the optimal operating speed of the distance elements, set zone 1 reach with a regular 80 to 85% of the line impedance reach setting, even when zone 1 is disabled.
GND DIST Z1 RCA — This setting specifies the characteristic angle (similar to the maximum torque angle in previous technologies) of the ground distance characteristic for the forward and reverse applications. In the non-directional applications, this setting defines the forward reach of the zone. The reverse reach impedance in the non-directional applications is set independently. This setting is independent from the GND DIST Z1 DIR RCA setting (the characteristic angle of an extra directional supervising function).
GND DIST Z1 REV REACH — This setting defines the reverse reach of the zone set to non-directional (GND DIST Z1 DIR setting).
The value must be entered in secondary ohms. This setting does not apply when the zone direction is set to “Forward” or “Reverse.”
GND DIST Z1 REV REACH RCA — This setting defines the angle of the reverse reach impedance if the zone is set to nondirectional (GND DIST Z1 DIR setting). This setting does not apply when the zone direction is set to “Forward” or “Reverse.”
GND DIST Z1 POL CURRENT — This setting applies only if the GND DIST Z1 SHAPE is set to “Quad” and controls the polarizing current used by the reactance comparator of the quadrilateral characteristic. Either the zero-sequence or negative sequence current can be used. In general, a variety of system conditions must be examined to select an optimum polarizing current. This setting becomes less relevant when the resistive coverage and zone reach are set conservatively.
Also, this setting is more relevant in lower voltage applications such as on distribution lines or cables, as compared with high-voltage transmission lines. This setting applies to both the zone 1 and reverse reactance lines if the zone is set to nondirectional.
In the case of Isolated/Compensated grounded systems, the relay internally uses loop current for polarization to handle cross country faults. As the use of loop current for polarization results in fixed tilt, the validity of this polarization is controlled by the following condition: |<I2 – <Iph|<45°
If this condition is not fulfilled, the assumption that the angle of fault current at fault point is close to the angle of Iph cannot be considered valid. Under such conditions, the quadrilateral characteristic can significantly overreach and underreach. To avoid this, the distance protection automatically switches from Quadrilateral to MHO characteristics to provide stable operation.
GND DIST Z1 NON-HOMOGEN ANG — This setting applies only if the GND DIST Z1 SHAPE is set to “Quad” and provides a method to correct the angle of the polarizing current of the reactance comparator for non-homogeneity of the zero sequence or negative-sequence networks. In general, a variety of system conditions must be examined to select this setting. In many applications this angle is used to reduce the reach at high resistances in order to avoid overreaching under far-out reach settings and/or when the sequence networks are greatly non-homogeneous. This setting applies to both the forward and reverse reactance lines if the zone is set to non- directional.
GND DIST Z1 COMP LIMIT — This setting shapes the operating characteristic. In particular, it enables a lens-shaped characteristic of the mho function and a tent-shaped characteristic of the quadrilateral function reactance boundary. If the mho shape is selected, the same limit angle applies to mho and supervising reactance comparators. In conjunction with the mho shape selection, this setting improves loadability of the protected line. In conjunction with the quadrilateral characteristic, this setting improves security for faults close to the reach point by adjusting the reactance boundary into a tent-shape.
GND DIST Z1 DIR RCA — Selects the characteristic angle (or maximum torque angle) of the directional supervising function. If the mho shape is applied, the directional function is an extra supervising function, as the dynamic mho characteristic itself is a directional one. In conjunction with the quadrilateral shape selection, this setting defines the only directional function built 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 the resistive axis of the impedance plane (see the Quadrilateral Distance Characteristic figure). The angular position of the blinder is adjustable with the use of the GND DIST Z1 QUAD RGT BLD RCA setting. This setting applies only to the quadrilateral
characteristic; 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 quadrilateral characteristic (see the Quadrilateral Distance Characteristic figure).
GND DIST Z1 QUAD LFT BLD — This setting defines the left blinder position of the quadrilateral characteristic along the resistive axis of the impedance plane (see the Quadrilateral Distance Characteristic figure). The angular position of the blinder is adjustable with the use of the GND DIST Z1 QUAD LFT BLD RCA setting. This setting applies only to the quadrilateral characteristic; 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 quadrilateral characteristic (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 the current supervision pickup to be less than the minimum 3I_0 current for the end of the zone fault, taking into account the required fault resistance coverage to prevent maloperation due to VT fuse failure. Settings less than 0.2 pu are not recommended, so apply them with caution. To enhance ground distance security against spurious neutral current during switch-off transients, three-phase faults, and phase-to-phase faults, a positive-sequence current restraint of 5% is applied to the neutral current supervision magnitude. Set this setting at least three times the CURRENT CUTOFF LEVEL setting. Zone 1 is sealed in with the current supervision.
GND DIST Z1 VOLT LEVEL — This setting is relevant for applications on series-compensated lines, or in general, if series capacitors are located between the relaying point and a point for which the zone shall not overreach. For plain (noncompensated) lines, set it to zero. Otherwise, the setting is entered in per unit of the VT bank configured under the DISTANCE SOURCE. Effectively, this setting facilitates dynamic current-based reach reduction. In non-directional applications (GND DIST Z1 DIR set to “Non-directional”), this setting applies only to the forward reach of the non-directional zone.
GND DIST Z1 DELAY — This setting enables the user to delay operation of the distance elements and implement a stepped distance backup protection. The distance element timer applies a short drop-out delay to cope with faults located close to the 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.