GE L90 Instruction Manual page 8
Line current differential system
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- Instruction manual (832 pages) ,
- Communications manual (532 pages) ,
- Instruction manual (752 pages)
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viii
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
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
8.1
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
L90 LINE CURRENT DIFFERENTIAL SYSTEM - INSTRUCTION MANUAL
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