Date Code 20001006
Loss-of-Potential, Load Encroachment, and Directional Element Logic
i
SEL-351 Instruction Manual
TABLE OF CONTENTS
Convert Maximum Loads to Equivalent Secondary Impedances..................................4-5
Apply Load-Encroachment Logic to a Phase Time-Overcurrent..................................4-6
Directional Control for Neutral Ground and Residual Ground Overcurrent Elements..................4-7
Best Choice Ground Directional™
Logic .........................................................................4-9
Directional Elements .........................................................................................................4-9
Directional Element Routing............................................................................................4-10
Internal Enables ..............................................................................................................4-18
Directional Elements .......................................................................................................4-19
Directional Element Routing............................................................................................4-19
Settings Made Automatically...........................................................................................4-26
Settings...........................................................................................................................4-27
DIR1 – Level 1 Overcurrent Element Direction Setting ............................................4-27
DIR2 – Level 2 Overcurrent Element Direction Setting ............................................4-27
DIR3 – Level 3 Overcurrent Element Direction Setting ............................................4-27
DIR4 – Level 4 Overcurrent Element Direction Setting ............................................4-27
ORDER – Ground Directional Element Priority Setting............................................4-28
50P32P – Phase Directional Element Three-Phase Current Pickup ...........................4-29
Z2F – Forward Directional Z2 Threshold.................................................................4-29
Z2R – Reverse Directional Z2 Threshold .................................................................4-29
50QFP and 50QRP Set Automatically..............................................................4-31
a2 – Positive-Sequence Current Restraint Factor, I
..............................................4-31
k2 – Zero-Sequence Current Restraint Factor, I
Summary of Contents for SEL-351
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