Schweitzer Engineering Laboratories SEL-387E - Page 46

ii Protection Functions Date Code 20080110
SEL-387E Instruction Manual
Independent Harmonic Blocking Element (IHBL) ....................................................3-24
Example of Setting the SEL-387E Relay for a Three-Winding Transformer .............3-25
Application Guidelines .......................................................................................................3-27
CT Arrangements........................................................................................................3-27
CT Sizing ....................................................................................................................3-27
CT Ratio Selection for a Multiwinding Transformer..................................................3-27
Restricted Earth Fault Element ...................................................................................................3-28
Application Description ......................................................................................................3-28
Operating Characteristic .....................................................................................................3-28
Setting Descriptions ............................................................................................................3-31
REF Directional Element Enable (E32I).....................................................................3-31
Operating Quantity from W1, W2 (32IOP).................................................................3-31
Positive-Sequence Current Restraint Factor, I0/I1 (a0) ..............................................3-31
Residual Current Sensitivity Threshold (50GP)..........................................................3-32
Setting Calculation..............................................................................................................3-32
Operating Quantity......................................................................................................3-32
Residual Current Sensitivity Threshold ......................................................................3-34
Overcurrent Element...................................................................................................................3-34
Application Description ......................................................................................................3-34
Operating Characteristic .....................................................................................................3-34
50Pn1 – Phase Definite-Time Element .......................................................................3-35
50Pn2 – Phase Instantaneous Element ........................................................................3-36
50Pn3 and 50Pn4 – Phase Instantaneous Element ......................................................3-36
51Pn – Phase Inverse-Time Element...........................................................................3-37
50Qn1 and 50Nn1 – Sequence Current Definite-Time Element Logic ......................3-38
50Qn1 Negative-Sequence Definite-Time Element............................................3-38
50Nn1 Residual Definite-Time Element .............................................................3-38
50Qn2 and 50Nn2 – Sequence Instantaneous Element Logic.....................................3-39
50Qn2 Negative-Sequence Instantaneous Element.............................................3-39
50Nn2 Residual Instantaneous Element..............................................................3-39
51Qn and 51Nn – Sequence Inverse-Time Elements..................................................3-39
51Qn Negative-Sequence Inverse-Time Element ...............................................3-40
51Nn Residual Inverse-Time Element ................................................................3-40
51PC1 and 51NC1 Combined Overcurrent Elements.................................................3-40
51PC1 and 51NC1 Element Logic ......................................................................3-41
Setting Descriptions ............................................................................................................3-46
Winding n Overcurrent Element and Demand Threshold Enables (EOCn)................3-46
Combined O/C Element Enable (EOCC)....................................................................3-46
Instantaneous and Definite-Time Element Pickups (50PnmP, 50QnmP,
50NnmP) .............................................................................................................
3-46
Definite-Time Element Delays (50Pn1D, 50Qn1D, 50Nn1D) ...................................3-46
Inverse-Time Element Pickups (51PnP, 51QnP, 51NnP, 51PC1P, 51NC1P) ............3-47
Curve Shape Settings (51PnC, 51QnC, 51NnC, 51PC1C, 51NC1C) .........................3-47
Time-Dial Settings (51PnTD, 51QnTD, 51NnTD, 51PC1TD, 51NC1TD)................3-47
Electromechanical Reset Settings (51PnRS, 51QnRS, 51NnRS, 51PC1RS,
51NC1RS) ...........................................................................................................
3-47
Torque-Control Settings (50PnmTC, 50QnmTC, 50NnmTC, 51PnTC,
51QnTC, 51NnTC)..............................................................................................
3-47
Application Guidelines .......................................................................................................3-47
Transformer Overcurrent Protection ...........................................................................3-47
Overcurrent Element Operating Quantities.................................................................3-48
Time-Overcurrent Element Settings............................................................................3-49