NR Electric PCS-9611 Instruction Manual page 31

3 Operation Theory
3 Operation Theory
Table of Contents
3.1 Overview ........................................................................................................................3-1
3.2 Fault Detectors .............................................................................................................3-1
3.3 Overcurrent Protection ..............................................................................................3-4
3.3.1 Definite Time Overcurrent Protection ............................................................................... 3-4
3.3.2 Inverse Definite Minimum Time Overcurrent Protection .................................................... 3-6
3.3.3 Voltage Control Element for Overcurrent Protection ......................................................... 3-9
3.3.4 Directional Element for Overcurrent Protection .............................................................. 3-10
3.3.5 Harmonic Blocking Element for Overcurrent Protection .................................................. 3-12
3.3.6 Heavy Current Blocking Element.................................................................................... 3-13
3.3.7 Overcurrent Protection Settings ..................................................................................... 3-13
3.4 Thermal Overload Protection ................................................................................ 3-16
3.4.1 Thermal Overload Protection Theory.............................................................................. 3-16
3.4.2 Thermal Overload Protection Settings ............................................................................ 3-18
3.5 Zero Sequence Overcurrent Protection.............................................................. 3-19
3.5.1 Definite Time Zero Sequence Overcurrent Protection..................................................... 3-19
3.5.2 IDMT Zero Sequence Overcurrent Protection................................................................. 3-21
3.5.3 Directional Element for Zero Sequence Overcurrent Protection...................................... 3-21
3.5.4 Harmonic Blocking Element for ROC Protection............................................................. 3-23
3.5.5 Zero Sequence Overcurrent Protection Settings ............................................................ 3-24
3.6 Sensitive Earth Fault Protection ........................................................................... 3-28
3.6.1 Definite Time Sensitive Earth Fault Protection................................................................ 3-28
3.6.2 IDMT Sensitive Earth Fault Protection............................................................................ 3-29
3.6.3 Directional Element for Sensitive Earth Fault Protection................................................. 3-29
3.6.4 Sensitive Earth Fault Protection Settings ....................................................................... 3-31
3.7 Negative Sequence Overcurrent Protection...................................................... 3-32
3-a
PCS-9611 Feeder Relay
Date: 2014-04-08