Schweitzer Engineering Laboratories SEL-351 - Section 3: Overcurrent, Voltage, Synchronism Check, Frequency, and Power Elements;Section 3: Overcurrent, Voltage, Synchronism Check, Frequency, and Power Elements

Date Code 20001006 Overcurrent, Voltage, Synchronism Check, Frequency, and Power Elements i
SEL-351 Instruction Manual
TABLE OF CONTENTS
SECTION 3: OVERCURRENT, VOLTAGE, SYNCHRONISM
CHECK, FREQUENCY, AND POWER ELEMENTS ................................ 3-1
Instantaneous/Definite-Time Overcurrent Elements ...................................................................3-1
Phase Instantaneous/Definite-Time Overcurrent Elements..................................................3-1
Settings Ranges.........................................................................................................3-1
Accuracy...................................................................................................................3-1
Pickup Operation.......................................................................................................3-3
Directional Control Option.........................................................................................3-5
Torque Control..........................................................................................................3-5
Combined Single-Phase Instantaneous Overcurrent Elements......................................3-6
Pickup and Reset Time Curves ..................................................................................3-7
Phase-to-Phase Instantaneous Overcurrent Elements..........................................................3-8
Setting Range............................................................................................................3-8
Accuracy...................................................................................................................3-8
Pickup Operation.......................................................................................................3-8
Pickup and Reset Time Curves ..................................................................................3-8
Neutral Ground Instantaneous/Definite-Time Overcurrent Elements...................................3-8
Settings Ranges.......................................................................................................3-11
Accuracy.................................................................................................................3-11
Pickup and Reset Time Curves ................................................................................3-11
Residual Ground Instantaneous/Definite-Time Overcurrent Elements...............................3-12
Settings Ranges.......................................................................................................3-13
Accuracy.................................................................................................................3-13
Pickup and Reset Time Curves ................................................................................3-13
Negative-Sequence Instantaneous/Definite-Time Overcurrent Elements............................3-14
Settings Ranges.......................................................................................................3-14
Accuracy.................................................................................................................3-14
Pickup and Reset Time Curves ................................................................................3-14
Time-Overcurrent Elements ....................................................................................................3-16
Phase Time-Overcurrent Elements...................................................................................3-16
Settings Ranges (51PT Element Example)................................................................3-17
Accuracy.................................................................................................................3-18
Logic Outputs (51PT Element Example)..................................................................3-18
Torque Control Switch Operation (51PT Element Example).....................................3-19
Torque Control Switch Closed..........................................................................3-19
Torque Control Switch Open............................................................................3-19
Control of Logic Point TCP .............................................................................3-20
Directional Control Option...............................................................................3-20
Torque Control ................................................................................................3-20
Reset Timing Details (51PT Element Example)........................................................3-21
Setting 51PRS = Y...........................................................................................3-21
Setting 51PRS = N...........................................................................................3-22
Operation of Single-Phase Time-Overcurrent Elements (51AT, 51BT, 51CT)...........3-22
Neutral Ground Time-Overcurrent Element .....................................................................3-24
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