Schweitzer Engineering SEL-351P - Page 220

ii Loss-of-Potential, Load Encroachment, and Directional Element Logic Date Code 990430
SEL-351P Manual Técnico
50GFP – Forward Directional Residual Ground Current Pickup ...............................4-33
50GRP – Reverse Directional Residual Ground Current Pickup ...............................
4-33
50GFP and 50GRP Set Automatically................................................................
4-33
a0 – Positive-Sequence Current Restraint Factor, I
0
/I
1
...............................................4-33
a0 Set Automatically ...........................................................................................
4-33
Z0F – Forward Directional Z0 Threshold...................................................................
4-34
Z0R – Reverse Directional Z0 Threshold ...................................................................
4-34
Z0F and Z0R Set Automatically .........................................................................
4-34
E32IV – SEL
OGIC Control Equation Enable ......................................................................4-34
Directional Control Provided by Torque Control Settings.........................................................
4-35
TABLES
Table 4.1: Overcurrent Elements Controlled by Level Direction Settings DIR1 through DIR4
(corresponding overcurrent element figure numbers in parentheses)..........................
4-28
FIGURES
Figure 4.1: Loss-of-Potential Logic...........................................................................................................4-1
Figure 4.2: Load-Encroachment Logic......................................................................................................
4-3
Figure 4.3: Migration of Apparent Positive-Sequence Impedance for a Fault Condition.........................
4-6
Figure 4.4: General Logic Flow of Directional Control for Neutral Ground and Residual Ground
Overcurrent Elements.....................................................................................................
4-8
Figure 4.5: Internal Enables (32QE and 32QGE) Logic for Negative-Sequence Voltage-Polarized
Directional Elements....................................................................................................
4-11
Figure 4.6: Internal Enable (32VE) Logic for Zero-Sequence Voltage-Polarized, Residual-
Current Directional Element ........................................................................................
4-12
Figure 4.7: Internal Enable (32NE) for Zero-Sequence Voltage-Polarized, Neutral-Current
Directional Element .....................................................................................................
4-12
Figure 4.8: Best Choice Ground Directional Logic ................................................................................
4-13
Figure 4.9: Negative-Sequence Voltage-Polarized Directional Element for Neutral Ground and
Residual Ground Overcurrent Elements ......................................................................
4-14
Figure 4.10: Zero-Sequence Voltage-Polarized, Residual-Current Directional Element for Neutral
Ground and Residual Ground Overcurrent Elements ..................................................
4-15
Figure 4.11: Zero-Sequence Voltage-Polarized, Neutral-Current Directional Elements for Neutral
Ground Overcurrent Elements .....................................................................................
4-16
Figure 4.12: Routing of Directional Elements to Residual Ground Overcurrent Elements ....................
4-17
Figure 4.13: Routing of Directional Elements to Neutral Ground Overcurrent Elements ......................
4-17
Figure 4.14: Direction Forward/Reverse Logic for Residual Ground Overcurrent Elements.................
4-18
Figure 4.15: Direction Forward/Reverse Logic for Neutral Ground Overcurrent Elements...................
4-19
Figure 4.16: General Logic Flow of Directional Control for Negative-Sequence and Phase
Overcurrent Elements...................................................................................................
4-20
Figure 4.17: Negative-Sequence Voltage-Polarized Directional Element for Negative-Sequence
and Phase Overcurrent Elements .................................................................................
4-23
Figure 4.18: Positive-Sequence Voltage-Polarized Directional Element for Phase Overcurrent
Elements.......................................................................................................................
4-24
Figure 4.19: Routing of Directional Elements to Negative-Sequence and Phase Overcurrent
Elements.......................................................................................................................
4-25