GE L90 User manual

GE
Grid Solutions
Instruction Manual
Product version: 7.6x
GE publication code: 1601-0081-AF1 (GEK-131004)
L90
Line Current Differential System
1601-0081-AF1
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Copyright © 2017 GE Multilin Inc. All rights reserved.
L90 Line Current Differential System Instruction Manual for version 7.6x.
L90, FlexLogic, FlexElement, FlexCurve, FlexAnalog, FlexInteger, FlexState, EnerVista,
CyberSentry, HardFiber, Multilin, and GE Multilin are trademarks or registered trademarks
of GE Multilin Inc.
The contents of this manual are the property of GE Multilin Inc. This documentation is
furnished on license and may not be reproduced in whole or in part without the permission
of GE Multilin. The content of this manual is for informational use only and is subject to
change without notice.
Part number: 1601-0081-AF1 (June 2017)

L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL iii
L90 Line Current Differential System
Table of contents
1INTRODUCTION 1.1 Safety symbols and definitions ........................................................................... 1-1
1.1.1 General cautions and warnings .................................................................................... 1-1
1.2 For further assistance........................................................................................... 1-2
2PRODUCT
DESCRIPTION
2.1 Product description ............................................................................................... 2-1
2.1.1 Features.................................................................................................................................... 2-3
2.2 Pilot channel relaying............................................................................................ 2-5
2.2.1 Inter-relay communications............................................................................................ 2-5
2.2.2 Channel monitor................................................................................................................... 2-7
2.2.3 Loopback test......................................................................................................................... 2-7
2.2.4 Direct transfer tripping ...................................................................................................... 2-8
2.3 Security .................................................................................................................... 2-8
2.4 Order codes...........................................................................................................2-11
2.4.1 Order codes with enhanced CT/VT modules.........................................................2-12
2.4.2 Order codes with process bus modules ..................................................................2-19
2.4.3 Replacement modules.....................................................................................................2-26
2.5 Signal processing................................................................................................. 2-28
2.5.1 UR signal processing ........................................................................................................2-28
2.6 Specifications........................................................................................................ 2-30
2.6.1 Protection elements..........................................................................................................2-31
2.6.2 User-programmable elements ....................................................................................2-40
2.6.3 Monitoring..............................................................................................................................2-42
2.6.4 Metering..................................................................................................................................2-43
2.6.5 Inputs .......................................................................................................................................2-44
2.6.6 Power supply........................................................................................................................2-45
2.6.7 Outputs....................................................................................................................................2-46
2.6.8 Communication protocols..............................................................................................2-48
2.6.9 Inter-relay communications..........................................................................................2-49
2.6.10 CyberSentry security.........................................................................................................2-50
2.6.11 Graphical front panel........................................................................................................2-50
2.6.12 Environmental......................................................................................................................2-51
2.6.13 Type tests...............................................................................................................................2-52
2.6.14 Production tests..................................................................................................................2-52
2.6.15 Approvals ...............................................................................................................................2-53
2.6.16 Maintenance.........................................................................................................................2-53

iv L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
TABLE OF CONTENTS
3 INSTALLATION 3.1 Unpack and inspect................................................................................................3-1
3.2 Panel cutouts...........................................................................................................3-2
3.2.1 Horizontal units......................................................................................................................3-2
3.2.2 Vertical units............................................................................................................................3-5
3.2.3 Rear terminal layout.........................................................................................................3-10
3.3 Wiring .....................................................................................................................3-12
3.3.1 Typical wiring.......................................................................................................................3-12
3.3.2 Dielectric strength .............................................................................................................3-13
3.3.3 Control power......................................................................................................................3-13
3.3.4 CT/VT modules ....................................................................................................................3-14
3.3.5 Process bus modules ....................................................................................................... 3-16
3.3.6 Contact inputs and outputs ..........................................................................................3-16
3.3.7 Transducer inputs and outputs...................................................................................3-27
3.3.8 RS232 port.............................................................................................................................3-29
3.3.9 CPU communication ports ............................................................................................3-30
3.3.10 IRIG-B.......................................................................................................................................3-32
3.4 Pilot channel communications...........................................................................3-33
3.4.1 Fiber: LED and ELED transmitters...............................................................................3-34
3.4.2 Fiber laser transmitters...................................................................................................3-34
3.4.3 G.703 interface....................................................................................................................3-35
3.4.4 RS422 interface...................................................................................................................3-39
3.4.5 Two-channel two-clock RS422 interface................................................................3-41
3.4.6 RS422 and fiber interface ..............................................................................................3-42
3.4.7 G.703 and fiber interface................................................................................................3-42
3.4.8 IEEE C37.94 interface .......................................................................................................3-43
3.4.9 C37.94SM interface...........................................................................................................3-46
3.5 Activate relay ........................................................................................................3-49
3.6 Install software.....................................................................................................3-50
3.6.1 EnerVista communication overview .........................................................................3-50
3.6.2 System requirements.......................................................................................................3-51
3.6.3 Install software....................................................................................................................3-51
3.7 Add device to software........................................................................................3-52
3.7.1 Set IP address in UR..........................................................................................................3-53
3.7.2 Configure serial connection..........................................................................................3-58
3.7.3 Configure Ethernet connection...................................................................................3-59
3.7.4 Configure modem connection.....................................................................................3-61
3.7.5 Automatic discovery of UR devices...........................................................................3-61
3.8 Connect to the L90 ...............................................................................................3-62
3.8.1 Connect to the L90 in EnerVista..................................................................................3-62
3.8.2 Use Quick Connect via the front panel RS232 port............................................3-63
3.8.3 Use Quick Connect via a rear Ethernet port..........................................................3-64
3.9 Set up CyberSentry and change default password........................................3-65
3.10 Import settings .....................................................................................................3-65
3.11 Connect to D400 gateway...................................................................................3-66
3.11.1 Oscillography files..............................................................................................................3-66
3.11.2 Event records.......................................................................................................................3-66
3.11.3 Log files...................................................................................................................................3-66
3.11.4 Setting files............................................................................................................................3-67
4INTERFACES 4.1 EnerVista software interface................................................................................4-1
4.1.1 Introduction .............................................................................................................................4-1
4.1.2 Settings files ............................................................................................................................4-1
4.1.3 Event viewing..........................................................................................................................4-2
4.1.4 File support ..............................................................................................................................4-3

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L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL v
4.1.5 EnerVista main window..................................................................................................... 4-3
4.1.6 Protection summary window ......................................................................................... 4-4
4.1.7 Settings templates............................................................................................................... 4-5
4.1.8 Secure and lock FlexLogic equations.......................................................................... 4-9
4.1.9 Settings file traceability ...................................................................................................4-12
4.2 Front panel interface...........................................................................................4-14
4.2.1 Front panel ............................................................................................................................4-14
4.2.2 Front panel display............................................................................................................4-17
4.2.3 Front panel navigation keys..........................................................................................4-38
4.2.4 LED indicators ......................................................................................................................4-40
4.2.5 Front panel labelling .........................................................................................................4-44
4.2.6 Menu navigation.................................................................................................................4-51
4.2.7 Change settings ..................................................................................................................4-53
4.2.8 View actual values.............................................................................................................4-58
4.2.9 Breaker control....................................................................................................................4-59
4.2.10 Change passwords............................................................................................................4-60
4.2.11 Invalid password entry ....................................................................................................4-62
4.3 Logic diagrams..................................................................................................... 4-62
4.4 FlexLogic design using Engineer ....................................................................... 4-63
4.4.1 Design logic...........................................................................................................................4-65
4.4.2 Send file to and from device .........................................................................................4-75
4.4.3 Monitor logic.........................................................................................................................4-76
4.4.4 View front panel and print labels................................................................................4-77
4.4.5 Generate connectivity report........................................................................................4-78
4.4.6 Preferences ...........................................................................................................................4-78
4.4.7 Toolbars ..................................................................................................................................4-82
5 SETTINGS 5.1 Settings menu......................................................................................................... 5-1
5.2 Overview.................................................................................................................. 5-4
5.2.1 Introduction to elements .................................................................................................. 5-4
5.2.2 Introduction to AC sources .............................................................................................. 5-6
5.3 Product setup.......................................................................................................... 5-8
5.3.1 Security ..................................................................................................................................... 5-8
5.3.2 Display properties ..............................................................................................................5-27
5.3.3 Graphical front panel........................................................................................................5-29
5.3.4 Clear relay records.............................................................................................................5-41
5.3.5 Communications ................................................................................................................5-42
5.3.6 Modbus user map ...........................................................................................................5-108
5.3.7 Real-time clock.................................................................................................................5-108
5.3.8 Fault reports ......................................................................................................................5-113
5.3.9 Oscillography.....................................................................................................................5-116
5.3.10 Data logger ........................................................................................................................5-118
5.3.11 Demand ...............................................................................................................................5-119
5.3.12 User-programmable LEDs ..........................................................................................5-121
5.3.13 User-programmable self-tests .................................................................................5-125
5.3.14 Control pushbuttons......................................................................................................5-126
5.3.15 User-programmable pushbuttons..........................................................................5-127
5.3.16 Flex state parameters...................................................................................................5-133
5.3.17 User-definable displays................................................................................................5-134
5.3.18 Installation..........................................................................................................................5-135
5.4 Remote resources..............................................................................................5-136
5.4.1 Remote resources configuration .............................................................................5-136
5.5 System setup.......................................................................................................5-137
5.5.1 AC inputs .............................................................................................................................5-137
5.5.2 Power system....................................................................................................................5-138

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5.5.3 Signal sources .................................................................................................................. 5-139
5.5.4 87L power system .......................................................................................................... 5-142
5.5.5 Breakers .............................................................................................................................. 5-150
5.5.6 Disconnect switch control .......................................................................................... 5-155
5.5.7 FlexCurves.......................................................................................................................... 5-160
5.5.8 Phasor Measurement Unit.......................................................................................... 5-167
5.6 FlexLogic.............................................................................................................. 5-187
5.6.1 FlexLogic operands........................................................................................................ 5-187
5.6.2 FlexLogic rules.................................................................................................................. 5-203
5.6.3 FlexLogic evaluation...................................................................................................... 5-204
5.6.4 FlexLogic example..........................................................................................................5-204
5.6.5 FlexLogic equation editor............................................................................................ 5-209
5.6.6 FlexLogic timers............................................................................................................... 5-209
5.6.7 FlexElements ..................................................................................................................... 5-209
5.6.8 Non-volatile latches.......................................................................................................5-214
5.7 Grouped elements............................................................................................. 5-216
5.7.1 Overview ............................................................................................................................. 5-216
5.7.2 Setting group 1................................................................................................................. 5-216
5.7.3 Line differential elements............................................................................................ 5-217
5.7.4 Line pickup ......................................................................................................................... 5-222
5.7.5 Distance............................................................................................................................... 5-224
5.7.6 Power swing detect (ANSI 68).................................................................................... 5-245
5.7.7 Load encroachment ...................................................................................................... 5-254
5.7.8 Phase current ................................................................................................................... 5-255
5.7.9 Neutral current................................................................................................................. 5-267
5.7.10 Wattmetric ground fault.............................................................................................. 5-275
5.7.11 Ground current ................................................................................................................ 5-279
5.7.12 Negative sequence current........................................................................................ 5-286
5.7.13 Breaker failure (ANSI 50BF)......................................................................................... 5-292
5.7.14 Voltage elements ............................................................................................................ 5-302
5.7.15 Supervising elements.................................................................................................... 5-314
5.7.16 Sensitive directional power........................................................................................ 5-321
5.8 Control elements ............................................................................................... 5-324
5.8.1 Overview ............................................................................................................................. 5-324
5.8.2 Trip bus ................................................................................................................................ 5-324
5.8.3 Setting groups .................................................................................................................. 5-326
5.8.4 Selector switch................................................................................................................. 5-328
5.8.5 Trip output.......................................................................................................................... 5-334
5.8.6 Underfrequency (ANSI 81U)........................................................................................ 5-340
5.8.7 Overfrequency (ANSI 81O) .......................................................................................... 5-341
5.8.8 Synchrocheck (ANSI 25) ............................................................................................... 5-342
5.8.9 Digital elements............................................................................................................... 5-347
5.8.10 Digital counters................................................................................................................ 5-350
5.8.11 Monitoring elements ..................................................................................................... 5-352
5.8.12 Pilot schemes.................................................................................................................... 5-376
5.8.13 Autoreclose (ANSI 79).................................................................................................... 5-399
5.8.14 Frequency rate of change (ANSI 81R).................................................................... 5-412
5.9 Inputs/outputs ................................................................................................... 5-413
5.9.1 Contact inputs.................................................................................................................. 5-413
5.9.2 Virtual inputs..................................................................................................................... 5-415
5.9.3 Contact outputs............................................................................................................... 5-416
5.9.4 Virtual outputs.................................................................................................................. 5-420
5.9.5 Direct inputs and outputs ........................................................................................... 5-420
5.9.6 Resetting ............................................................................................................................. 5-421
5.10 Transducer inputs/outputs.............................................................................. 5-422
5.10.1 DCmA inputs...................................................................................................................... 5-422

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L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL vii
5.10.2 RTD inputs...........................................................................................................................5-423
5.10.3 DCmA outputs...................................................................................................................5-425
5.11 Testing..................................................................................................................5-428
5.11.1 Test mode function.........................................................................................................5-428
5.11.2 Test mode forcing ...........................................................................................................5-429
5.11.3 Phasor Measurement Unit test values..................................................................5-429
5.11.4 Force contact inputs......................................................................................................5-431
5.11.5 Force contact outputs...................................................................................................5-431
5.11.6 Channel tests.....................................................................................................................5-432
6 ACTUAL VALUES 6.1 Actual Values menu............................................................................................... 6-1
6.2 Front panel .............................................................................................................. 6-3
6.3 Status .......................................................................................................................6-4
6.3.1 Contact inputs ....................................................................................................................... 6-4
6.3.2 Virtual inputs........................................................................................................................... 6-4
6.3.3 RxGOOSE boolean inputs.................................................................................................. 6-5
6.3.4 RxGOOSE DPS inputs .......................................................................................................... 6-5
6.3.5 Direct inputs............................................................................................................................ 6-5
6.3.6 Contact outputs .................................................................................................................... 6-5
6.3.7 Virtual outputs ....................................................................................................................... 6-6
6.3.8 RxGOOSE status.................................................................................................................... 6-6
6.3.9 RxGOOSE statistics .............................................................................................................. 6-6
6.3.10 Autoreclose ............................................................................................................................. 6-7
6.3.11 Channel tests.......................................................................................................................... 6-7
6.3.12 Digital counters ..................................................................................................................... 6-8
6.3.13 Selector switches.................................................................................................................. 6-9
6.3.14 Flex states................................................................................................................................ 6-9
6.3.15 Ethernet .................................................................................................................................... 6-9
6.3.16 Real time clock synchronizing........................................................................................ 6-9
6.3.17 Remaining connection status.......................................................................................6-10
6.3.18 Parallel Redundancy Protocol (PRP)...........................................................................6-11
6.3.19 TxGOOSE status ..................................................................................................................6-11
6.4 Metering.................................................................................................................6-12
6.4.1 Metering conventions.......................................................................................................6-12
6.4.2 Differential current ............................................................................................................6-16
6.4.3 Sources....................................................................................................................................6-17
6.4.4 Sensitive directional power ...........................................................................................6-23
6.4.5 Synchrocheck.......................................................................................................................6-23
6.4.6 Tracking frequency............................................................................................................6-24
6.4.7 Frequency rate of change..............................................................................................6-24
6.4.8 FlexElements.........................................................................................................................6-24
6.4.9 RxGOOSE analogs ..............................................................................................................6-25
6.4.10 Wattmetric ground fault .................................................................................................6-25
6.4.11 Phasor Measurement Unit.............................................................................................6-25
6.4.12 PMU aggregator..................................................................................................................6-26
6.4.13 Volts per hertz......................................................................................................................6-26
6.4.14 Restricted ground fault....................................................................................................6-27
6.4.15 Transducer inputs and outputs ...................................................................................6-27
6.4.16 Distance..................................................................................................................................6-27
6.5 Records ..................................................................................................................6-29
6.5.1 Fault reports .........................................................................................................................6-29
6.5.2 Event records .......................................................................................................................6-30
6.5.3 Oscillography........................................................................................................................6-32
6.5.4 Data logger ...........................................................................................................................6-32
6.5.5 Phasor Measurement Unit records............................................................................6-33

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
7COMMANDSAND
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

TABLE OF CONTENTS
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL ix
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
9 COMMISSIONING 9.1 Testing......................................................................................................................9-1
9.1.1 Channel testing ..................................................................................................................... 9-1
9.1.2 Clock synchronization tests............................................................................................. 9-2
9.1.3 Current differential .............................................................................................................. 9-3
9.1.4 Local-remote relay tests...................................................................................................9-4
10 THEORY OF
OPERATION
10.1 Overview................................................................................................................ 10-1
10.1.1 L90 design..............................................................................................................................10-1
10.1.2 L90 architecture..................................................................................................................10-2
10.1.3 Removal of decaying offset...........................................................................................10-2
10.1.4 Phaselet computation......................................................................................................10-2
10.1.5 Disturbance detection......................................................................................................10-3
10.1.6 Fault detection.....................................................................................................................10-3
10.1.7 Ground differential element..........................................................................................10-5
10.1.8 Clock synchronization ......................................................................................................10-6
10.1.9 Frequency tracking and phase locking....................................................................10-6
10.1.10 Frequency detection.........................................................................................................10-7
10.1.11 Phase detection ..................................................................................................................10-8
10.1.12 Phase locking filter..........................................................................................................10-10
10.1.13 Matching phaselets........................................................................................................10-11
10.1.14 Start-up................................................................................................................................10-12
10.1.15 Hardware and communication requirements...................................................10-12
10.1.16 Online estimate of measurement errors..............................................................10-12
10.1.17 CT saturation detection................................................................................................10-13
10.1.18 Charging current compensation..............................................................................10-14
10.1.19 Differential element characteristics .......................................................................10-15
10.1.20 Relay synchronization...................................................................................................10-16
10.2 Operating condition characteristics ..............................................................10-17
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 Distance elements analysis........................................................................................10-28
10.4 Phase distance applied to power transformers...........................................10-31
10.4.1 Description .........................................................................................................................10-31
10.4.2 Example ...............................................................................................................................10-35
10.5 Single-pole tripping ...........................................................................................10-37
10.5.1 Overview..............................................................................................................................10-37
10.5.2 Phase selection ................................................................................................................10-40
10.5.3 Communications channels for pilot-aided schemes......................................10-42
10.5.4 Permissive echo signaling...........................................................................................10-48
10.5.5 Pilot scheme / phase selector coordination .......................................................10-49
10.5.6 Cross-country fault example .....................................................................................10-50
10.6 Fault locator........................................................................................................10-51

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10.6.1 Overview ............................................................................................................................. 10-51
10.6.2 Multi-ended fault locator............................................................................................. 10-51
10.6.3 Single-ended fault locator.......................................................................................... 10-58
11 MAINTENANCE 11.1 Monitoring .............................................................................................................11-1
11.1.1 Devices with Site Targets ...............................................................................................11-1
11.1.2 Data with Modbus Analyzer..........................................................................................11-1
11.2 General maintenance ..........................................................................................11-3
11.2.1 In-service maintenance..................................................................................................11-3
11.2.2 Out-of-service maintenance ........................................................................................11-3
11.2.3 Unscheduled maintenance (system interruption) ..............................................11-3
11.3 Retrieve files..........................................................................................................11-3
11.3.1 CyberSentry security event files..................................................................................11-4
11.4 Convert device settings.......................................................................................11-5
11.5 Copy settings to other device ............................................................................11-7
11.6 Compare settings .................................................................................................11-7
11.6.1 Compare against defaults.............................................................................................11-7
11.6.2 Compare two devices ...................................................................................................... 11-8
11.7 Back up and restore settings .............................................................................11-8
11.7.1 Back up settings .................................................................................................................11-8
11.7.2 Restore settings............................................................................................................... 11-11
11.8 Upgrade software.............................................................................................. 11-13
11.9 Upgrade firmware ............................................................................................. 11-13
11.10 Replace front panel........................................................................................... 11-15
11.11 Replace module ................................................................................................. 11-23
11.12 Battery................................................................................................................. 11-24
11.12.1 Replace battery for SH/SL power supply............................................................. 11-24
11.12.2 Dispose of battery .......................................................................................................... 11-26
11.13 Clear files and data after uninstall ................................................................ 11-29
11.14 Repairs................................................................................................................. 11-29
11.15 Storage ................................................................................................................ 11-30
11.16 Disposal............................................................................................................... 11-30
AFLEXANALOG
OPERANDS
A.1 FlexAnalog items ................................................................................................... A-1
B RADIUS SERVER
CONFIGURATION
B.1 RADIUS server configuration ................................................................................B-1
C COMMAND LINE
INTERFACE
C.1 Command line interface ....................................................................................... C-1
D MISCELLANEOUS D.1 Warranty ................................................................................................................. D-1
D.2 Revision history ..................................................................................................... D-1
ABBREVIATIONS
INDEX

L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL 1-1
L90 Line Current Differential System
Chapter 1: Introduction
Introduction
This chapter outlines safety and technical support information.
1.1 Safety symbols and definitions
Before attempting to install or use the device, review all safety indicators in this document to help prevent injury,
equipment damage, or downtime.
The following safety and equipment symbols are used in this document.
1.1.1 General cautions and warnings
The following general safety precautions and warnings apply.
Follow the requirements of this manual, including adequate wiring size and type, terminal torque settings, voltage,
current magnitudes applied, and adequate isolation/clearance in external wiring from high to low voltage circuits.
Use the device only for its intended purpose and application.
Ensure that all ground paths are uncompromised for safety purposes during device operation and service.
Ensure that the control power applied to the device, the alternating current (AC), and voltage input match the ratings
specified on the relay nameplate. Do not apply current or voltage in excess of the specified limits.
Indicates a hazardous situation which, if not avoided, will result in death or serious injury.
Indicates a hazardous situation which, if not avoided, could result in death or serious injury.
Indicates a hazardous situation which, if not avoided, could result in minor or moderate injury.
Indicates practices not related to personal injury.
Ensure that all connections to the product are correct so as to avoid accidental risk of shock
and/or fire, for example such as can arise from high voltage connected to low voltage terminals.

1-2 L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
FOR FURTHER ASSISTANCE CHAPTER 1: INTRODUCTION
1
Only qualified personnel are to operate the device. Such personnel must be thoroughly familiar with all safety
cautions and warnings in this manual and with applicable country, regional, utility, and plant safety regulations.
Hazardous voltages can exist in the power supply and at the device connection to current transformers, voltage
transformers, control, and test circuit terminals. Make sure all sources of such voltages are isolated prior to
attempting work on the device.
Hazardous voltages can exist when opening the secondary circuits of live current transformers. Make sure that
current transformer secondary circuits are shorted out before making or removing any connection to the current
transformer (CT) input terminals of the device.
For tests with secondary test equipment, ensure that no other sources of voltages or currents are connected to such
equipment and that trip and close commands to the circuit breakers or other switching apparatus are isolated,
unless this is required by the test procedure and is specified by appropriate utility/plant procedure.
When the device is used to control primary equipment, such as circuit breakers, isolators, and other switching
apparatus, all control circuits from the device to the primary equipment must be isolated while personnel are working
on or around this primary equipment to prevent any inadvertent command from this device.
Use an external disconnect to isolate the mains voltage supply.
Personal safety can be affected if the product is physically modified by the end user. Modifications to the product
outside of recommended wiring configuration, hardware, or programming boundaries is not recommended end-use
practice. Product disassembly and repairs are not permitted. All service needs to be conducted by the factory.
1.2 For further assistance
For product support, contact the information and call center as follows:
GE Grid Solutions
650 Markland Street
Markham, Ontario
Canada L6C 0M1
Worldwide telephone: [phone]
Europe/Middle East/Africa telephone: [phone]
North America toll-free: 1 800 547 8629
Fax: [phone]
Worldwide e-mail: multilin.t[email protected]
Europe e-mail: multilin.tech.[email protected]
Website: http://www.gegridsolutions.com/multilin
When contacting GE by e-mail, optionally include a device information file, which is generated in the EnerVista software by
clicking the Service Report button. When using the optional graphical front panel, the report instead can be generated by
connecting a USB drive to the front panel.
LED transmitters are classified as IEC 60825-1 Accessible Emission Limit (AEL) Class 1M. Class 1M
devices are considered safe to the unaided eye. Do not view directly with optical instruments.
This product is rated to Class A emissions levels and is to be used in Utility, Substation Industrial
environments. Not to be used near electronic devices rated for Class B levels.

CHAPTER 1: INTRODUCTION FOR FURTHER ASSISTANCE
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL 1-3
1
Figure 1-1: Generate service report in EnerVista software

1-4 L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
FOR FURTHER ASSISTANCE CHAPTER 1: INTRODUCTION
1

L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL 2-1
L90 Line Current Differential System
Chapter 2: Product description
Product descript ion
This chapter outlines the product, order codes, and specifications.
2.1 Product description
The L90 Line Current Differential System is part of the Universal Relay (UR) series of products. It is a digital current
differential relay system with an integral communications channel interface. It is a complete line terminal protection and
control system, able to deliver protection as either a line differential and/or distance device. Both distance and line
differential elements can run simultaneously.
The L90 provides complete protection for transmission lines of any voltage level. Both three phase and single phase
tripping schemes are available. Models of the L90 are available for application on both two and three terminal lines. The
L90 uses per-phase-differential at 64 kbps transmitting two phaselets per cycle. The current differential scheme is based
on innovative patented techniques developed by GE. The L90 algorithms are based on the Fourier transform–phaselet
approach and an adaptive statistical restraint. The restraint is similar to a traditional percentage differential scheme, but is
adaptive based on relay measurements. When used with a 64 kbps channel, the innovative phaselets approach yields an
operating time of 1.0 to 1.5 cycles (typical). The adaptive statistical restraint approach provides both sensitive and accurate
fault sensing. This allows the L90 to detect relatively higher impedance single line to ground faults that existing systems do
not. The basic current differential element operates on current input only. Long lines with significant capacitance can
benefit from charging current compensation if terminal voltage measurements are applied to the relay. The voltage input
is also used for some protection and monitoring features such as directional elements, fault locator, metering, and
distance backup. In addition, the L90 provides local restricted ground fault protection.
The L90 operates over different communications links with various degrees of noise encountered in power systems and
communications environments. Since correct operation of the relay is completely dependent on data received from the
remote end, special attention must be paid to information validation. The L90 incorporates a high degree of security by
using a 32-bit CRC cyclic redundancy code (CRC) inter-relay communications packet.
Several options are available for communication. An RS232 port (USB port with the graphical front panel) can be used to
connect to a computer for the programming of settings and the monitoring of actual values. The rear RS485 port allows
independent access by operating and engineering staff. It can be connected to system computers with baud rates up to
115.2 kbps. All serial ports use the Modbus RTU protocol. The IEC 60870-5-103 protocol is supported on the RS485
interface. Also only one of the DNP, IEC 60870-5-103, and IEC 60870-5-104 protocols can be enabled at any time on the
relay. When the IEC 60870-5-103 protocol is chosen, the RS485 port has a fixed even parity and the baud rate can be
either 9.6 kbps or 19.2 kbps. The 100Base-FX or 100Base-TX Ethernet interface provides fast, reliable communications in
noisy environments. The Ethernet port supports IEC 61850, Modbus/TCP, TFTP, and PTP (according to IEEE Std. 1588-2008
or IEC 61588), and it allows access to the relay via any standard web browser (L90 web pages). The IEC 60870-5-104
protocol is supported on the Ethernet port. The Ethernet port also supports the Parallel Redundancy Protocol (PRP) of IEC

2-2 L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
PRODUCT DESCRIPTION CHAPTER 2: PRODUCT DESCRIPTION
2
62439-3 (clause 4, 2012) when purchased as an option.
Secure Routable GOOSE (R-GOOSE) is supported with software options.
In addition to current differential protection, the relay provides multiple backup protection for phase and ground faults. For
overcurrent protection, the time overcurrent curves can be selected from a selection of standard curve shapes or a
custom FlexCurve™ for optimum co-ordination. Additionally, five zones of phase and ground distance protection with
power swing blocking, out-of-step tripping, line pickup, load encroachment, and six pilot schemes are included.
The L90 incorporates charging current compensation for applications on very long transmission lines without loss of
sensitivity. The line capacitive current is removed from the terminal phasors.
For breaker-and-a-half or ring applications, the L90 design provides secure operation during external faults with possible
current transformation (CT) saturation.
Voltage, current, and power metering are built in as standard features. Current parameters are available as total
waveform RMS magnitude, or as fundamental frequency only root mean square (RMS) magnitude and angle (phasor).
Settings and actual values can be accessed from the front panel or EnerVista software.
The L90 uses flash memory technology that allows field upgrading as new features are added. Firmware and software are
upgradable.
The following single-line diagram illustrates the relay functionality using American National Standards Institute (ANSI)
device numbers.
Table 2-1: ANSI device numbers and functions supported
Device number Function Device number Function
21G Ground distance 51_2 Negative-sequence time overcurrent
21P Phase distance 52 AC circuit breaker
24 Volts per hertz 59C Compensated overvoltage
25 Synchrocheck 59N Neutral overvoltage
27P Phase undervoltage 59P Phase overvoltage
27X Auxiliary undervoltage 59X Auxiliary overvoltage
32N Wattmetric zero-sequence directional 67N Neutral directional overcurrent
32R Sensitive reverse power 67P Phase directional overcurrent
49 Thermal overload protection 67_2 Negative-sequence directional overcurrent
50BF Breaker failure 68 Power swing blocking
50DD Adaptive fault detector
(sensitive current disturbance detector) 78 Out-of-step tripping
79 Automatic recloser
50G Ground instantaneous overcurrent 81O Overfrequency
50N Neutral instantaneous overcurrent 81R Rate of change of frequency
50P Phase instantaneous overcurrent 81U Underfrequency
50_2 Negative-sequence instantaneous overcurrent 87RGF Restricted ground fault
51G Ground time overcurrent 87L Segregated line current differential
51N Neutral time overcurrent 87LG Ground line current differential
51P Phase time overcurrent

CHAPTER 2: PRODUCT DESCRIPTION PRODUCT DESCRIPTION
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL 2-3
2
Figure 2-1: Single-line diagram
Table 2-2: Other device functions
2.1.1 Features
2.1.1.1 Line current differential
• Phase segregated, high-speed digital current differential system
• Overhead and underground AC transmission lines, series compensated lines
Function Function Function
Breaker Arcing Current (I2t) Fault Locator Oscillography
Breaker Control Fault Reporting Pilot Schemes
Breaker Flashover FlexElements™ (8) Setting Groups (6)
Broken Conductor Detection FlexLogic™ Equations Stub Bus
Contact Inputs (up to 120) IEC 60870-5-103 Communications Synchrophasor (PMU)
Contact Outputs (up to 72) IEC 61850 Communications Time synchronization over IRIG-B or IEEE
1588
Control Pushbuttons IEC 62351-9 Data and Communications
Security Time Synchronization over SNTP
CT Failure Detector L90 Channel Tests Transducer Inputs/Outputs
CyberSentry™ Security Line Pickup User Definable Displays
Data Logger Load Encroachment User Programmable LEDs
Digital Counters (8) Metering: Current, Voltage, Power, Energy,
Frequency, Demand, Power Factor, 87L
current, local and remote phasors,
harmonics, THD
User Programmable Pushbuttons
Digital Elements (48) Modbus Communications User Programmable Self-Tests
Direct Inputs (8 per L90 comms channel) Modbus User Map Virtual Inputs (64)
Disconnect Switches Non-Volatile Latches Virtual Outputs (96)
DNP 3.0 or IEC 60870-5-104 protocol Non-Volatile Selector Switch VT Fuse Failure
Event Recorder Open Pole Detector

2-4 L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
PRODUCT DESCRIPTION CHAPTER 2: PRODUCT DESCRIPTION
2
• Two-terminal and three-terminal line applications
• Zero-sequence removal for application on lines with tapped transformers connected in a grounded wye on the line
side
• GE phaselets approach based on the Discrete Fourier Transform with 64 samples per cycle and transmitting two time-
stamped phaselets per cycle
• Adaptive restraint approach improving sensitivity and accuracy of fault sensing
• Increased security for trip decision using disturbance detector and trip output logic
• Accommodates in-zone transformer with a magnitude and phase compensation and second harmonic inhibit during
transformer magnetizing inrush
• Continuous clock synchronization via the distributed synchronization technique
• Increased transient stability through DC decaying offset removal
• Accommodates up to five times CT ratio differences
• Peer-to-peer (master-master) architecture changing to master-slave via DTT (if channel fails) at 64 kbps
• Charging current compensation
• Interfaces direct fiber, multiplexed RS422, IEEE C37.94, and G.703 connections with relay ID check
• Per-phase line differential protection direct transfer trip plus eight user-assigned pilot signals via the communications
channel
• Secure 32-bit CRC protection against communications errors
• Channel asymmetry (up to 10 ms) compensation using GPS satellite-controlled clock
2.1.1.2 Backup protection
• DTT provision for pilot schemes
• Five zones of distance protection with six pilot schemes, power swing blocking and out-of-step tripping, line pickup,
and load encroachment
• Two-element time overcurrent and two-element instantaneous overcurrent directional phase overcurrent protection
• Two-element time overcurrent and two-element instantaneous overcurrent directional zero-sequence protection
• Two-element time overcurrent and two-element instantaneous overcurrent negative-sequence overcurrent
protection
• Undervoltage and overvoltage protection
2.1.1.3 Additional protection
• Breaker failure protection
• Stub bus protection
• VT and CT supervision
• GE Multilin sources approach allowing grouping of different CTs and VTs from multiple input channels
• Open pole detection
• Breaker trip coil supervision and seal-in of trip command
• FlexLogic allowing creation of user-defined distributed protection and control logic
2.1.1.4 Control
• One and two breaker configuration for breaker-and-a-half and ring bus schemes, pushbutton control from the relay
• Auto-reclosing and synchrochecking
• Breaker arcing current
2.1.1.5 Monitoring
• Oscillography of current, voltage, FlexLogic operands, and digital signals (1 ×128 cycles to 31 ×8 cycles configurable)
• Events recorder: 1024 events

CHAPTER 2: PRODUCT DESCRIPTION PILOT CHANNEL RELAYING
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL 2-5
2
• Fault locator
2.1.1.6 Metering
• Actual 87L remote phasors, differential current, channel delay, and channel asymmetry at all line terminals of line
current differential protection
• Line current, voltage, real power, reactive power, apparent power, power factor, and frequency
2.1.1.7 Communications
• Front panel RS232 port: 19.2 kbps
• Rear RS485 port: up to 115 kbps
• Rear 100Base-FX Ethernet port supporting the IEC 61850 protocol
2.2 Pilot channel relaying
2.2.1 Inter-relay communications
Dedicated inter-relay communications can operate over 64 kbps digital channels or dedicated fiber optic channels.
Available interfaces include:
• RS422 at 64 kbps
• G.703 at 64 kbps
• Dedicated fiber optics at 64 kbps, including
– 820 nm multimode fiber with an LED transmitter
– 1300 nm multimode fiber with an LED transmitter
– 1300 nm single-mode fiber with an ELED transmitter
– 1300 nm single-mode fiber with a laser transmitter
– 1550 nm single-mode fiber with a laser transmitter
– IEEE C37.94 820 nm multimode fiber with an LED transmitter
All fiber optic options use an ST connector. L90 models are available for use on two or three terminal lines. A two terminal
line application requires one bidirectional channel. However, in two terminal line applications, it is also possible to use an
L90 relay with two bidirectional channels. The second bidirectional channel provides a redundant backup channel with
automatic switchover if the first channel fails.
The L90 current differential relay is designed to function in a peer-to-peer or master-to-master architecture. In the peer-to-
peer architecture, all relays in the system are identical and perform identical functions in the current differential scheme. In
order for every relay on the line to be a peer, each relay must be able to communicate with all of the other relays. If there is
a failure in communications among the relays, the relays revert to a master-to-peer architecture on a three-terminal
system, with the master as the relay that has current phasors from all terminals. Using two different operational modes
increases the dependability of the current differential scheme on a three-terminal system by reducing reliance on
communications.
The main difference between a master and a slave L90 is that only a master relay performs the actual current differential
calculation, and only a master relay communicates with the relays at all other terminals of the protected line.
At least one master L90 relay must have live communications to all other terminals in the current differential scheme; the
other L90 relays on that line operate as slave relays. All master relays in the scheme are equal, and each performs all
functions. Each L90 in the scheme determines if it is a master by comparing the number of terminals on the line to the
number of active communication channels.
The slave terminals only communicate with the master; there is no slave-to-slave communications path. As a result, a
slave L90 cannot calculate the differential current. When a master L90 relay issues a local trip signal, it also sends a direct
transfer trip (DTT) signal to all of the other L90 relays on the protected line.

2-6 L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
PILOT CHANNEL RELAYING CHAPTER 2: PRODUCT DESCRIPTION
2
If a slave L90 issues a trip from one of its backup functions, it can send a transfer trip signal to its master and other slave
relays if such option is designated. Because a slave cannot communicate with all the relays in the differential scheme, the
master then “broadcasts” the direct transfer trip (DTT) signal to all other terminals.
The slave L90 performs the following functions:
• Samples currents and voltages
• Removes DC offset from the current via the mimic algorithm
• Creates phaselets
• Calculates sum of squares data
• Transmits current data to all master L90 relays
• Performs all local relaying functions
• Receives current differential DTT and Direct Input signals from all other L90 relays
• Transmits direct output signals to all communicating relays
• Sends synchronization information of local clock to all other L90 clocks
The master L90 relay performs the following functions:
• Performs all functions of a slave L90
• Receives current phasor information from all relays
• Performs the current differential algorithm
• Sends a current differential DTT signal to all L90 relays on the protected line
In the peer-to-peer mode, all L90 relays act as masters.