TABLE OF CONTENTS
L90 LINE CURRENT DIFFERENTIAL SYSTEM - INSTRUCTION MANUAL
9.1
Testing ............................................................................................................... 9-1
9.1.1
Channel testing ..................................................................................................................... 9-1
9.1.2
9.1.3
Current differential .............................................................................................................. 9-3
9.1.4
Local-remote relay tests ................................................................................................... 9-4
10.1 Overview ......................................................................................................... 10-1
10.1.1
L90 design..............................................................................................................................10-1
10.1.2
L90 architecture..................................................................................................................10-2
10.1.3
10.1.4
Phaselet computation......................................................................................................10-2
10.1.5
Disturbance detection......................................................................................................10-3
10.1.6
Fault detection.....................................................................................................................10-3
10.1.7
10.1.8
Clock synchronization ......................................................................................................10-6
10.1.9
10.1.10 Frequency detection.........................................................................................................10-7
10.1.11 Phase detection ..................................................................................................................10-8
10.1.13 Matching phaselets........................................................................................................10-11
10.1.14 Start-up ................................................................................................................................10-12
10.2.1
Description .........................................................................................................................10-17
10.2.2
Trip decision example ...................................................................................................10-19
10.2.3
Trip decision test..............................................................................................................10-19
10.3 Distance elements.......................................................................................10-20
10.3.1
Introduction........................................................................................................................10-20
10.3.2
Phasor estimation ...........................................................................................................10-21
10.3.3
Distance characteristics ..............................................................................................10-21
10.3.4
Fast distance algorithm ...............................................................................................10-26
10.3.5
Memory polarization...................................................................................................... 10-27
10.3.6
10.4.1
Description .........................................................................................................................10-31
10.4.2
Example ...............................................................................................................................10-35
10.5.1
Overview..............................................................................................................................10-37
10.5.2
Phase selection ................................................................................................................10-40
10.5.3
10.5.4
10.5.5
10.5.6
10.6 Fault locator .................................................................................................10-51
10.6.1
Overview..............................................................................................................................10-51
10.6.2
10.6.3
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