Overview
The “Negative sequence directional overcurrent” element provides both forward and reverse fault direction indications through its output operands NEG SEQ DIR OC1 FWD and NEG SEQ DIR OC1 REV, respectively. The output operand is asserted if the magnitude of the operating current is above a pickup level (overcurrent unit) and the fault direction is seen as forward or reverse, respectively (directional unit).
For more detailed information “Negative sequence directional overcurrent” element, refer to GE, Universal Relay (UR) family of products, Version 8.0x manuals.
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Setting Parameters
Modbus memory map for Setting parameters
| Products | Hex address | Register name | Range | Units | Step | Format | Default |
| C70, D30, D60, F60, G30, G60, L60, L90, T60 | 49F2 | Negative Sequence Directional Overcurrent 1 Function | 0 to 1 | — | 1 | F102 | 0 (Disabled) |
| " | 49F3 | Negative Sequence Directional Overcurrent 1 Source | 0 to 5 | — | 1 | F167 | 0 (SRC 1) |
| " | 49F4 | Negative Sequence Directional Overcurrent 1 Type | 0 to 1 | — | 1 | F179 | 0 (Neg Sequence) |
| " | 49F5 | Neg Sequence Directional Overcurrent 1 Forward ECA | 0 to 90 | °Lag | 1 | F002 | 75 |
| " | 49F6 | Neg Seq Directional Overcurrent 1 Forward Limit Angle | 40 to 90 | degrees | 1 | F001 | 90 |
| " | 49F7 | Neg Sequence Directional Overcurrent 1 Forward Pickup | 0.015 to 30 | pu | 0.005 | F001 | 50 |
| " | 49F8 | Neg Seq Directional Overcurrent 1 Reverse Limit Angle | 40 to 90 | degrees | 1 | F001 | 90 |
| " | 49F9 | Neg Sequence Directional Overcurrent 1 Reverse Pickup | 0.015 to 30 | pu | 0.005 | F001 | 50 |
| " | 49FA | Negative Sequence Directional Overcurrent 1 Target | 0 to 2 | — | 1 | F109 | 0 (Self-reset) |
| " | 49FB | Negative Sequence Directional Overcurrent 1 Block | 0 to 4294967295 | — | 1 | F300 | 0 |
| " | 49FD | Negative Sequence Directional Overcurrent 1 Events | 0 to 1 | — | 1 | F102 | 0 (Disabled) |
| " | 49FE | Negative Sequence Directional Overcurrent 1 Offset | 0 to 250 | ohms | 0.01 | F001 | 0 |
| " | 49FF | Negative Sequence Directional Overcurrent 1 Pos Seq Restraint | 0 to 0.5 | — | 0.001 | F001 | 63 |
| " | 4A00 | Reserved (3 items) | 0 to 1 | — | 1 | F001 | 0 |
| " | 4A03 | …Repeated for Neg Seq Directional Overcurrent 2 | |||||
| T60 | 4A14 | …Repeated for Neg Seq Directional Overcurrent 3 |
| F102 | 0 = Disabled, 1 = Enabled | ||||||
| F109 | 0 = Self-reset, 1 = Latched, 2 = Disabled | ||||||
| F167 | 0 = SRC 1, 1 = SRC 2, 2 = SRC 3, 3 = SRC 4, 4 = SRC 5, 5 = SRC 6 | ||||||
| F179 | 0 = Neg Sequence, 1 = Zero Sequence | ||||||
| F300 | 0 : Off (This is boolean FALSE value), 1 : On (This is boolean TRUE value) | ||||||
Logics & highlights
Definitions
Negative-sequence directional characteristic for a phase A to ground fault
Negative-sequence directional OC1 logic
Definition of Setting Parameters
NEG SEQ DIR OC1 OFFSET — Specifies the offset impedance used by this protection. The primary application for the offset impedance is to guarantee correct identification of fault direction on series compensated lines . In regular applications, the offset impedance ensures proper operation even if the negative-sequence voltage at the relaying point is very small. If this is the intent, the offset impedance shall not be larger than the negative- sequence impedance of the protected circuit. Practically, it is several times smaller. Enter the offset impedance in secondary ohms.
NEG SEQ DIR OC1 TYPE — Selects the operating mode for the overcurrent unit of the element. The choices are “Neg Sequence” and “Zero Sequence.” In some applications it is advantageous to use a directional negative-sequence overcurrent function instead of a directional zero-sequence overcurrent function as inter-circuit mutual effects are minimized.
NEG SEQ DIR OC1 POS-SEQ RESTRAINT — Controls the positive-sequence restraint. Set it to 0.063 (in “Zero Sequence” mode) or 0.125 (in “Neg Sequence” mode) for backward compatibility with revisions 3.40 and earlier. Set it to zero to remove the restraint. Set it higher if large system unbalances or poor CT performance are expected.
NEG SEQ DIR OC1 FWD ECA — Select the element characteristic angle (ECA) for the forward direction. The element characteristic angle in the reverse direction is the angle set for the forward direction shifted by 180°.
NEG SEQ DIR OC1 FWD LIMIT ANGLE — Defines a symmetrical limit angle (in both directions from the ECA) for the forward direction.
NEG SEQ DIR OC1 FWD PICKUP — Defines the pickup level for the overcurrent unit in the forward direction. This pickup threshold applies to zero-sequence or negative-sequence current based on the NEG SEQ DIR OC1 TYPE setting. When specifying this setting, keep in mind that the design uses a positive-sequence restraint technique.
NEG SEQ DIR OC1 REV LIMIT ANGLE — Defines a symmetrical limit angle (in both directions from the ECA) for the reverse direction.
NEG SEQ DIR OC1 REV PICKUP — Defines the pickup level for the overcurrent unit in the reverse direction. This pickup threshold applies to zero-sequence or negative-sequence current based on the NEG SEQ DIR OC1 TYPE setting. When selecting this setting, keep in mind that the design uses a positive-sequence restraint technique.