GE L90 Instruction Manual page 8

7 COMMANDS AND
TARGETS
8 APPLICATION OF
SETTINGS
viii
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
8.8.1 Instantaneous element error during L90 synchronization.............................8-25
8.9 Phase distance through power transformers ..........................................8-26
8.9.1 Phase distance protection............................................................................................. 8-26
8.9.2 Example.................................................................................................................................. 8-27
L90 LINE CURRENT DIFFERENTIAL SYSTEM - INSTRUCTION MANUAL
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