Schweitzer Engineering Laboratories SEL-351 - Section 4: Loss-Of-Potential, Load Encroachment, and Directional Element Logic;Section 4: Loss-Of-Potential, Load Encroachment, and Directional Element Logic

Date Code 20001006 Loss-of-Potential, Load Encroachment, and Directional Element Logic i
SEL-351 Instruction Manual
TABLE OF CONTENTS
SECTION 4: LOSS-OF-POTENTIAL, LOAD ENCROACHMENT,
AND DIRECTIONAL ELEMENT LOGIC ................................................... 4-1
Loss-of-Potential Logic.............................................................................................................4-1
Setting ELOP = Y or Y1...................................................................................................4-2
Setting ELOP = Y.............................................................................................................4-2
Setting ELOP = N.............................................................................................................4-2
Load-Encroachment Logic........................................................................................................4-3
Settings Ranges.................................................................................................................4-4
Load-Encroachment Setting Example ................................................................................4-4
Convert Maximum Loads to Equivalent Secondary Impedances..................................4-5
Convert Power Factors to Equivalent Load Angles.............................................................4-5
Apply Load-Encroachment Logic to a Phase Time-Overcurrent..................................4-6
Use SEL-321 Relay Application Guide for the SEL-351 Relay ..........................................4-7
Directional Control for Neutral Ground and Residual Ground Overcurrent Elements..................4-7
Internal Enables ................................................................................................................4-9
Best Choice Ground Directional™ Logic .........................................................................4-9
Directional Elements .........................................................................................................4-9
Directional Element Routing............................................................................................4-10
Loss-of-Potential .....................................................................................................4-10
Direction Forward/Reverse Logic....................................................................................4-10
Directional Control for Negative-Sequence and Phase Overcurrent Elements ...........................4-18
Internal Enables ..............................................................................................................4-18
Directional Elements .......................................................................................................4-19
Directional Element Routing............................................................................................4-19
Loss-of-Potential .....................................................................................................4-19
Direction Forward/Reverse Logic....................................................................................4-20
Directional Control Settings....................................................................................................4-26
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
Z2F and Z2R Set Automatically.......................................................................4-30
50QFP – Forward Directional Negative-Sequence Current Pickup............................4-30
50QRP – Reverse Directional Negative-Sequence Current Pickup ............................4-30
50QFP and 50QRP Set Automatically..............................................................4-31
a2 – Positive-Sequence Current Restraint Factor, I
2
/I
1
..............................................4-31
a2 Set Automatically........................................................................................4-31
k2 – Zero-Sequence Current Restraint Factor, I
2
/I
0
...................................................4-31
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