Schweitzer Engineering Laboratories SEL-300G - Page 36

ii Relay Element Settings
Date Code 20020206 SEL-300G Instruction Manual
Recommendations .......................................................................................................2-27
Reverse-Power Tripping..............................................................................................2-28
Element Operating Characteristics......................................................................................2-28
Loss-of-Field Element.................................................................................................................2-29
Element Description............................................................................................................2-29
Functional Description ................................................................................................2-29
Setting Descriptions ....................................................................................................2-30
Relay Word Bits ..........................................................................................................2-31
Setting Calculation ..............................................................................................................2-32
Information Needed.....................................................................................................2-32
Recommendations .......................................................................................................2-32
Loss-of-Field Protection Using a Negative Offset Zone 2 ..................................2-32
Loss-of-Field Protection Using a Positive Offset Zone 2....................................2-33
Element Operating Characteristics......................................................................................2-34
Negative-Sequence Overcurrent Elements..................................................................................2-35
Element Description............................................................................................................2-35
Functional Description ................................................................................................2-35
Setting Descriptions ....................................................................................................2-35
Relay Word Bits ..........................................................................................................2-36
Setting Calculation ..............................................................................................................2-37
Information Needed.....................................................................................................2-37
Recommendations .......................................................................................................2-37
Negative-Sequence Overcurrent Tripping...................................................................2-37
Element Operating Characteristics......................................................................................2-38
Overcurrent Elements..................................................................................................................2-40
Element Description............................................................................................................2-40
Functional Description ................................................................................................2-40
Overcurrent Protection, All Relay Models..........................................................2-40
Overcurrent Protection, Relay Models With Differential Protection..................2-40
Setting Descriptions ....................................................................................................2-41
Definite-Time Overcurrent Settings ....................................................................2-41
Definite-Time 50/87 Overcurrent Settings..........................................................2-42
Neutral Time-Overcurrent Settings .....................................................................2-42
Residual Time-Overcurrent Settings ...................................................................2-43
Relay Word Bits ..........................................................................................................2-43
Neutral Overcurrent Setting Calculation.............................................................................2-45
Information Needed.....................................................................................................2-45
Recommendations .......................................................................................................2-45
Neutral Overcurrent Tripping......................................................................................2-46
Other Overcurrent Elements........................................................................................2-46
Element Operating Characteristics......................................................................................2-46
Pickup and Reset Time Curves....................................................................................2-46
Time-Overcurrent Curves ...........................................................................................................2-51
U.S. Moderately Inverse Curve: U1 ...........................................................................2-51
I.E.C. Class A Curve (Standard Inverse): C1.............................................................2-51
U.S. Inverse Curve: U2...............................................................................................2-51
I.E.C. Class B Curve (Very Inverse): C2 ...................................................................2-51
U.S. Very Inverse Curve: U3......................................................................................2-51
I.E.C. Class C Curve (Extremely Inverse): C3...........................................................2-51
U.S. Extremely Inverse Curve: U4 .............................................................................2-51