GE L90

viii L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
TABLE OF CONTENTS
6.5.6 Breaker maintenance ......................................................................................................6-33
6.6 Product information.............................................................................................6-34
6.6.1 Model information .............................................................................................................6-34
6.6.2 Firmware revisions............................................................................................................6-34
7COMMANDS AND
TARGETS
7.1 Commands menu ...................................................................................................7-1
7.1.1 Virtual inputs ...........................................................................................................................7-2
7.1.2 Clear records...........................................................................................................................7-2
7.1.3 Set date and time..................................................................................................................7-3
7.1.4 Relay maintenance ..............................................................................................................7-3
7.1.5 Phasor Measurement Unit one-shot ...........................................................................7-4
7.1.6 Security......................................................................................................................................7-6
7.2 Targets menu ..........................................................................................................7-6
7.2.1 Target messages...................................................................................................................7-7
7.2.2 Relay self-tests .......................................................................................................................7-7
8 APPLICATION OF
SETTINGS
8.1 CT requirements .....................................................................................................8-1
8.1.1 Introduction .............................................................................................................................8-1
8.1.2 CT saturation analysis tool...............................................................................................8-2
8.2 Current differential (87L) settings .......................................................................8-3
8.2.1 Introduction .............................................................................................................................8-3
8.2.2 Current differential pickup................................................................................................8-4
8.2.3 Current differential restraint 1........................................................................................8-4
8.2.4 Current differential restraint 2........................................................................................8-4
8.2.5 Current differential break point......................................................................................8-4
8.2.6 CT tap..........................................................................................................................................8-4
8.2.7 Breaker-and-a-half..............................................................................................................8-6
8.2.8 Distributed bus protection................................................................................................8-9
8.3 Channel asymmetry compensation using GPS...............................................8-10
8.3.1 Introduction ..........................................................................................................................8-10
8.3.2 Compensation method 1................................................................................................8-10
8.3.3 Compensation method 2................................................................................................8-11
8.3.4 Compensation method 3................................................................................................8-12
8.4 Distance backup/supervision.............................................................................8-13
8.4.1 Overview ................................................................................................................................8-13
8.4.2 Phase distance....................................................................................................................8-14
8.4.3 Ground distance.................................................................................................................8-15
8.5 Protection signaling schemes............................................................................8-16
8.5.1 Overview ................................................................................................................................8-16
8.5.2 Direct under-reaching transfer trip (DUTT) ............................................................8-17
8.5.3 Permissive under-reaching transfer trip (PUTT)...................................................8-17
8.5.4 Permissive over-reaching transfer trip (POTT)......................................................8-17
8.5.5 Hybrid POTT scheme (HYB-POTT)................................................................................8-18
8.5.6 Directional comparison blocking................................................................................8-19
8.5.7 Directional comparison unblocking..........................................................................8-19
8.6 Series compensated lines ...................................................................................8-21
8.6.1 Distance settings................................................................................................................8-21
8.6.2 Ground directional overcurrent ..................................................................................8-23
8.7 Lines with tapped transformers ........................................................................8-23
8.7.1 Overview ................................................................................................................................8-23
8.7.2 Transformer load currents ............................................................................................8-24
8.7.3 LV-side faults........................................................................................................................8-24
8.7.4 External ground faults .....................................................................................................8-24
8.8 Instantaneous elements .....................................................................................8-25