Schweitzer Engineering Laboratories SEL-300G User manual

SEL-300G
MULTIFUNCTION GENERATOR RELAY
INSTRUCTION MANUAL
SCHWEITZER ENGINEERING LABORATORIES
2350 NE HOPKINS COURT
PULLMAN, WA USA 99163-5603
TEL: [phone] FAX: [phone]

!
WARNING: This device is shipped with default
passwords. Default passwords should be changed to
private passwords at installation. Failure to change each
default password to a private password may allow
unauthorized access. SEL shall not be responsible for
any damage resulting from unauthorized access.
!
ADVERTISSEMENT: Cet appareil est expédié avec des mots
de passe par défaut. A l'installation, les mots de passe par
défaut devront être changés pour des mots de passe
confidentiels. Dans le cas contraire, un accès non-autorisé à
l'équipement pourrait être possible. SEL décline toute
responsabilité pour tout dommage résultant de cet accès non-
autorisé.
!
CAUTION: Be sure to follow the generator and prime
mover manufacturers’ guidelines with respect to
generator operation and commissioning.
!ATTENTION: Suivez attentivement les instructions des
manufacturiers de la turbine et de la génératrice pour la
réception, la mise en route et l'opération.
!
CAUTION:Do not apply reverse polarity dc voltage or ac
voltage to terminals Z25 and Z26 of SEL-300G Relays
rated for 24/48 Vdc applications. Relay failure and
permanent power supply damage will result from
application of reverse polarity dc voltage to relays rated
for 24/48 Vdc applications.
!
ATTENTION: N’appliquer pas un voltage CC avec polarité
inversée ou un voltage CA, sur les bornes Z35 et Z26 des relais
300G dont la tension d’alimentation nominale est 24/48 VCC.
Une perte de fonctionnement du relais et un bris permanent de
l’alimentation résulteraient de l’application d’une polarité CC
inversée sur un relais avec tension nominale de 24/48 VCC.
!
CAUTION: Standard SEL relay output contacts are rated
to make and carry trip coil current, but are not rated to
interrupt trip coil current. Do not exceed the contact
interrupt ratings shown in Relay Specifications and
Options.
!
ATTENTION: Les contacts standards des relais SEL ont la
capacité de fermer sur le courant spécifié des bobines
d’ouverture mais ne peuvent ouvrir sur le même courant. Il est
important de ne pas dépasser les capacités des contacts
indiquées an paragraphe Spécifications du Relais et
Options.
!
CAUTION: The relay contains devices sensitive to
electrostatic discharge (ESD). When working on the
relay with front or top cover removed, work surfaces and
personnel must be properly grounded or equipment
damage may result.
!
ATTENTION: Le relais contient des pièces sensibles aux
décharges électrostatiques. Quand on travaille sur le relais
avec les panneaux avant ou du dessus enlevés, toutes les
surfaces et le personnel doivent être mis à la terre
convenablement pour éviter les dommages à l'équipement.
!
DANGER: Removal of relay front panel exposes circuitry
which may cause electrical shock that can result in injury
or death.
!
DANGER: Le retrait du panneau avant expose à la circuiterie
qui pourrait être la source de chocs électriques pouvant
entraîner des blessures ou la mort.
!
DANGER: Contact with this circuitry may cause
electrical shock that can result in injury or death.
!
DANGER: Le contact avec la circuiterie peut causer un choc
électrique pouvant entraîner des blessures ou la mort.
!
DANGER: Contact with instrument terminals may cause
electrical shock which can result in injury or death. !
DANGER: Le contact avec les bornes de l' instrument peut
causer un choc électrique pouvant entraîner des blessures ou la
mort.
The software (firmware), schematic drawings, relay commands, and relay messages are copyright protected by the United States
Copyright Law and International Treaty provisions. All rights are reserved.
You may not copy, alter, disassemble, or reverse-engineer the software. You may not provide the software to any third party.
All brand or product names appearing in this document are the trademark or registered trademark of their respective holders.
Schweitzer Engineering Laboratories, SELOGIC, Connectorized, Job Done, SEL-PROFILE, SEL-5030 ACSELERATOR, and
are registered trademarks of Schweitzer Engineering Laboratories, Inc.
The English language manual is the only approved SEL manual.
Copyright © SEL 1998–2002 (All rights reserved) Printed in USA.
This product is covered by U.S. Patent Numbers: 5,208,545; 5,317,472; 5,367,426; 5,652,688; 5,883,578, 5,041,737; 5,479,315;
and U.S. Patent(s) Pending; Foreign Patents issued.
This product is covered by the standard SEL 10-year warranty. For warranty details, visit www.selinc.com or contact your
customer service representative.
PM300G-01

SEL-300G Instruction Manual Date Code 20020206
SEL-300G INSTRUCTION MANUAL
TABLE OF CONTENTS
SECTION 1:INTRODUCTION ANDSPECIFICATIONS
SECTION 2:RELAY ELEMENT SETTINGS
SECTION 3:AUXILIARYFUNCTION SETTINGS
SECTION 4:SELOGIC®CONTROL EQUATIONS
SECTION 5:INSTALLATION
SECTION 6:ENTER RELAYSETTINGS
SECTION 7:RELAY COMMISSIONING
SECTION 8: MONITORING AND METERING FUNCTIONS
SECTION 9:FRONT-PANEL OPERATION
SECTION 10:SERIAL PORT COMMUNICATIONSAND COMMANDS
SECTION 11:EVENT REPORTSAND SER FUNCTIONS
SECTION 12:MAINTAIN AND TROUBLESHOOT RELAY
SECTION 13:DIFFERENTIAL ELEMENT SETTINGS
SECTION 14:APPENDICES
AppendixA:FirmwareVersions
Appendix B:DifferentialConnection Diagrams
Appendix C:SEL DistributedPort SwitchProtocol
Appendix D:Configuration,Fast Meter, and FastOperateCommands
Appendix E:Compressed ASCIICommands
Appendix F:Modbus®RTUCommunicationsProtocol
SECTION 15:COMMAND SUMMARY

SEL-300G Instruction Manual Date Code 20020206
MANUAL CHANGE INFORMATION
The date code at the bottom of each page of this manual reflects the creation or revision date.
Date codes are changed only on pages that have been revised and any following pages affected
by the revisions (i.e., pagination). If significant revisions are made to a section, the date code on
all pages of the section will be changed to reflect the revision date.
Each time revisions are made, both the main table of contents and the affected individual section
table of contents are regenerated and the date code is changed to reflect the revision date.
Changes in this manual to date are summarized below (most recent revisions listed at top).
Revision Date Summary of Revisions
The Manual Change Information section has been created to begin a record of revisions to this
manual. All changes will be recorded in this Summary of Revisions table.
20020206 Section 1—Add projection mount information, 220 Vdc optoisolated inputs,
and miscellaneous changes.
Section 2—Added references, corrected drawings, and clarified information.
Section 3—Updated Alias Settings.
Section 4—Miscellaneous updates.
Section 5—Updated Figure 5.1.
Section 6—Added Modbus®settings and miscellaneous updates to Settings
Sheets.
Section 7—Miscellaneous updates.
Section 10—Added Modbus Protocol.
Section 11—Miscellaneous updates.
Section 13—Miscellaneous updates.
Appendix A—Updated firmware versions.
Appendix D—Updated A5CO Relay Definition Block.
Appendix F—New Appendix—Modbus Protocol.
20011003 Appendix A—Updated firmware versions.
20010824 Section 1—Updated UL/CSA certifications
Section 7—Updated Differential Element Commissioning Worksheet
20010615 Section 6—Added error message to Table 6.3
Settings Sheet—Revised ranges of CTR, CTRD, 87N1P, & 87N2P
Section 10—Added reference to AB phase; clarified FREQ.
Section 11—Changed symbols for 64G1 and 64G2
Section 12—Changed upgrade instructions to include SEL-2020 or SEL-2030
Communications Processor connection.
Appendix A—Updated firmware versions.

ii Manual Change Information
Date Code 20020206 SEL-300G Instruction Manual
Revision Date Summary of Revisions
20001212 Section 1—Added thermal protection of generator and prime mover; revised
relay specifications; added optional RTD elements; power supply output
contacts; tightening torque and terminal connections; add RTD phrase to
protection and control processing.
Section 2—Added section on RTD based protection.
Section 4—Revised Table 4.6 and Table 4.7.
Section 5—Revised EIA-232 Serial Port Voltage Jumpers and Clock Battery.
Section 6—Revised table 6.3; Insert RTD based protection in settings sheet.
Section 10—Added MET T command.
Appendix A—Updated firmware versions.
20000616 Reissued entire manual with new date code.
Section 1—Added Connectorized®and panel-mount models, features, and
ordering options; added 110 Vdc power supply option; revised relay
specifications; added Out-of-Step Element to setting ranges and accuracies;
revised timing accuracy for volts/hertz (24) element.
Section 2—Added description of the 78 element; set processing rate for 40 and
78 elements at one-half cycle; revised pickup time for 50 element; and
corrected minor typographical errors; latch variables increased to 16; number o
f
15-cycle event reports reduced to 29.
Section 3—Revised SER triggering to accommodate 78 element; local bits
increased to 16.
Section 4—Added 78 element to trip equations; revised Relay Word bit
definitions; increased latch, remote, and local bits to 16; increased display
points to 16; revised Tables 4.6 and 4.7.
Section 5—Added discussion and related data for the Connectorized and panel-
mount versions.
Section 6—Added setting entries for the 78 element; revised Settings Sheets to
reflect increased local, remote, and latch bits, and display points.
Section 7—Added commissioning details for the 78 element.
Section 9—Increased local bits to 16.
Section 10—Added references to SEL-2030 wherever applicable; added new
screen captures to reflect addition of 78 element; revised Relay Word bit tables;
reduced number of 15-cycle event reports to 29; revised Table 10.7.
Section 11—Revised Event Report Columns and Sample Event Report to
reflect 78 element; reduced number of 15-cycle event reports to 29.
Appendix A—Updated firmware versions.
Appendix D—Revised sample DNA message outputs.
Appendix E—Revised Relay Word bit lists; revised sample CEV outputs.

Manual Change Information iii
SEL-300G Instruction Manual Date Code 20020206
Revision Date Summary of Revisions
20000615 Section 2—Negative-Sequence magnitude of 3 • I2replaced by I2on pages 2-40
and 2-49.
20000218 Appendix A—Updated firmware versions.
19990421 Section 1—Added 24 Vdc relay part number option.
Section 7—Added 24 Vdc option to commissioning description.
Appendix A—Updated firmware versions.
19990312 Section 2—Corrected phase distance element reach setting instructions on Page
2-14.
Section 7—Corrected phase distance element testing instructions on Page 7-23.
19990115 Section 2—Corrected Enable Backup Protection setting on Page 2-8 and
Enable Overvoltage Protection setting on Page 2-9.
Section 4—Corrected setting name for Synch-Check Phase on Page 4-25.
Section 4—Corrected typographical error in Figure 4.18 on Page 4-41.
19981125 Section 1—Updated power supply information in General Specifications on
Page 1-16.
Section 2—Updated phase distance element logic diagram on Page 2-16.
Section 2—Off-Frequency Accumulators, Setting Descriptions—adjusted
Accumulator Time-Delayed Pickup range on Page 2-78.
Section 5—Updated Relay Dimension and Panel Cutout drawing on Page 5-1.
Changed voltage amount to 200 V continuous in Potential Transformer Inputs
section on Page 5-9. Modified Figure 5.17 on Page 5-16.
Settings Sheets—Added Voltage Ratio Correction Factor, 25RCF setting on
Page 3. Added setting name for Independent Harmonic Blocking Setting
(IHBL) on Page 10.
Section 7—Miscellaneous edits from Page 7-19 through the end of the section.
Section 8—Clarified Differential Metering quantities on page 8-12.
Section 10—SHO Command (Show/View Settings)—Reworded sentence at the
bottom of Page 10-23.
Section 13—Changed IRS1 equation to read “IRS1 = 3 per unit of TAP” on
Pages 13-10 and 13-15.
Appendix A—Updated firmware versions.
19980731 Add danger warnings (in English and French) against electrical shock, fire,
energy/high current levels and mechanical hazards to be in compliance with
North American Product Safety guidelines.

iv Manual Change Information
Date Code 20020206 SEL-300G Instruction Manual
Revision Date Summary of Revisions
19980717 Create Relay Models 0300G2 and 0300G3, making synch-check option
available.
Add support for open-delta pts.
Add 27PP2, 59PP2 phase-to-phase voltage elements.
Add 21P phase mho distance elements, add EBUP setting to enable one backup
protection element at a time.
Add 87N ground differential element to models 0300G0 and 0300G2.
Add single-phase 50H2 element settings to models 0300G1 and 0300G3.
Reduce maximum voltage element setting to 200.0 V secondary
Remove 51P phase time-overcurrent element.
Add error message tables; add relay model tables to Section 1.
Modify page format.
19980429 Modify Appendix A.
19980417 Correct typographical errors; Clarify relay setting precision.
19980320 Added Section 13: Differential Element Settings;
Added differential element test information and Differential Element
Commissioning Worksheet to Section 7: Relay Commissioning;
Moved VNOM and INOM settings from Global to Group setting;
Added MET DIF and EVE DIF command descriptions;
Clarified the calculation of the 64G2P setting.
19980130 Initial Release.

SEL-300G Instruction Manual Date Code 20020206
TABLE OF CONTENTS
SECTION 1: INTRODUCTION AND SPECIFICATIONS ......................1-1
Welcome .......................................................................................................................................1-1
Typographic Conventions .............................................................................................................1-2
SEL-300G Relay Models ..............................................................................................................1-2
Instruction Manual Sections Overview.........................................................................................1-4
SEL-300G Relay Protection Applications ....................................................................................1-6
Complete Generator Primary Protection...............................................................................1-6
Feature-Rich Generator Backup Protection ..........................................................................1-7
Protection for Small- and Medium-Sized Machines .............................................................1-7
Solidly Grounded Machine Protection..................................................................................1-8
Thermal Protection of Generator and Prime Mover .............................................................1-8
SEL-300G Relay Generator Protection Features ..........................................................................1-8
SEL-300G Relay Additional Features ..........................................................................................1-9
Contact I/O Application ................................................................................................................1-9
Available Contact Input/Output Options...............................................................................1-9
Power Supply and Optoisolated Input DC Voltages...........................................................1-10
Serial Communication Connections (typical).............................................................................1-11
SEL-5801 Cable SELECTOR Software ................................................................................1-12
SEL-300G Relay Ordering..........................................................................................................1-12
Place a Request for Quotation or Order ..............................................................................1-12
Create a Relay Part Number (Screw-Terminal Block Option)............................................1-13
Create a Relay Part Number (Connectorized Option).........................................................1-15
Special Specifications .........................................................................................................1-16
Communication Cables .......................................................................................................1-16
Relay Specifications and Options ...............................................................................................1-17
General ................................................................................................................................1-17
Processing Specifications....................................................................................................1-19
Relay Element Setting Ranges and Accuracies...................................................................1-19
TABLES
Table 1.1: SEL-300G Relay Instruction Manual Task Map .....................................................................1-1
Table 1.2: SEL-300G Relay Models.........................................................................................................1-2
Table 1.3: SEL-300G Relay Hardware Models ........................................................................................1-3
Table 1.4: SEL-300G Relay (Screw-Terminal Block) Part Number Creation Table .............................1-13
Table 1.5: SEL-300G Relay (Connectorized) Part Number Creation Table ..........................................1-15

ii Introduction and Specifications
Date Code 20020206 SEL-300G Instruction Manual
FIGURES
Figure 1.1: Large Generator Primary and Backup Protection...................................................................1-6
Figure 1.2: Generator Differential Zone May Include Transformer.........................................................1-7
Figure 1.3: Simple Protection for Resistance Grounded Generators........................................................1-7
Figure 1.4: Generator Thermal Protection with SEL-2600 & SEL-300G Relay......................................1-8
Figure 1.5: SEL-300G Relay Communication Connection Examples....................................................1-11

Introduction and Specifications 1-1
SEL-300G Instruction Manual Date Code 20020206
SECTION 1: INTRODUCTION AND SPECIFICATIONS
WELCOME
This instruction manual covers the SEL-300G Relay family. This manual contains the
information you need to select, set, install, test, operate, and maintain any SEL-300G Relay. You
probably will not need to review the whole book to perform the specific tasks for which you are
responsible. Table 1.1 should help you refer to the best SEL-300G Relay Instruction Manual
section for the tasks you need to perform.
Table 1.1: SEL-300G Relay Instruction Manual Task Map
Task Refer to Instruction Manual Sections
Select a Relay Model Section 1: Introduction and Specifications;
SEL 300G Relay Models, SEL-300G Relay Ordering
Design the Installation Section 5: Installation; Example AC and DC
Connection Diagrams
Appendix B: Differential Connection Diagrams
Calculate Relay Element Settings Section 2: Relay Element Settings
Section 13: Differential Element Settings
Section 6: Enter Relay Settings; Setting Sheets
Create SELOGIC®Control Equations
Settings, Tripping, Closing, and
Synch-Check Settings
Section 4: SELOGIC Control Equations
Create Demand Meter, DC Monitor,
Setting Group Selection, Breaker
Monitor, and Sequential Events
Recorder (SER) Function Settings
Section 3: Auxiliary Function Settings
Install the Relay Section 5: Installation
Section 7: Relay Commissioning
Enter Relay Settings Section 6: Enter Relay Settings
Section 9: Front-Panel Operation
Section 10: Serial Port Communications and
Commands
Commission Test the Relay Section 7: Relay Commissioning
Operate the Relay Section 8: Monitoring and Metering Functions
Section 9: Front-Panel Operation
Section 11: Event Reports and SER Functions
Section 12: Maintain and Troubleshoot Relay

1-2 Introduction and Specifications
Date Code 20020206 SEL-300G Instruction Manual
TYPOGRAPHIC CONVENTIONS
• In this manual, commands you type appear in bold/uppercase: OTTER.
• Computer keys you press appear in bold/uppercase/brackets: <ENTER>.
• Examples of relay serial port command responses look like:
=>
• Examples of information that can appear in the relay front-panel LCD display look like:
GEN SHUTDOWN ←→
Position: RETURN
• Sections of this instruction manual are shown in bold italics: Section 1: Introduction and
Specifications.
SEL-300G RELAY MODELS
This instruction manual covers the following SEL-300G Relay models:
Table 1.2: SEL-300G Relay Models
Model
Synch-
Check
Differential
Protection
Compatible
with SEL-2600
Modbus®
Protocol Voltage Inputs Current Inputs
0300G0 No 87N No Optional VA, VB, VC, VN
or
VAB, VCB, VN
IA, IB, IC, IN
0300G1 No 87 Optional Optional VA, VB, VC, VN
or
VAB, VCB, VN
IA, IB, IC, IN
IA87, IB87, IC87
0300G2 Yes 87N Optional Optional VA, VB, VC, VN, VS
or
VAB, VCB, VN, VS
IA, IB, IC, IN
0300G3 Yes 87 Optional Optional VA, VB, VC, VN, VS
or
VAB, VCB, VN, VS
IA, IB, IC, IN
IA87, IB87, IC87

Introduction and Specifications 1-3
SEL-300G Instruction Manual Date Code 20020206
Table 1.3: SEL-300G Relay Hardware Models
Model
Mounting
Type
Rack Unit
Height (I/O)*
Rear-Panel
Connection
Type
Output
Contact
Type
Reference
Figures
0300G_0H Rack 2U 6/8 screw-terminal
block
standard 5.1, 5.2,
5.4–5.7
0300G_03 Panel 2U 6/8 screw-terminal
block
standard 5.1, 5.3,
5.4–5.7
0300G_1H Rack 3U 6/8 screw-terminal
block
standard 5.1, 5.2,
5.4–5.7
8/12 screw-terminal
block
standard or
high current
interrupting
0300G_13 Panel 3U 6/8 screw-terminal
block
standard 5.1, 5.3,
5.4–5.7
8/12 screw-terminal
block
standard or
high current
interrupting
0300G_WH Rack 2U 6/8 Connectorized® standard 5.1, 5.2,
5.8–5.11
0300G_W3 Panel 2U 6/8 Connectorized standard 5.1, 5.3,
5.8–5.11
0300G_YH Rack 3U 6/8 Connectorized standard 5.1, 5.2,
5.8–5.11
8/12 Connectorized standard or
high current
interrupting
0300G_Y3 Panel 3U 6/8 Connectorized standard 5.1, 5.3,
5.8–5.11
8/12 Connectorized standard or
high current
interrupting
* Number of Optoisolated Input/Output Contacts
The model numbers in Table 1.2 and Table 1.3 are only part of an actual ordering number—
enough to distinguish one model type from another. They should not be used to order an
SEL-300G Relay. Refer to SEL-300G Relay Ordering at the end of this section.
Throughout this instruction manual, when differences among the SEL-300G Relay models in
Table 1.3 are explained, model numbers are referenced for clarity.

1-4 Introduction and Specifications
Date Code 20020206 SEL-300G Instruction Manual
INSTRUCTION MANUAL SECTIONS OVERVIEW
The following is an overview of the other sections in this instruction manual:
Section 2: Relay Element Settings describes the relay generator protection elements, their
logic and operating characteristics, and the calculation of their settings.
Section 3: Auxiliary Function Settings describes the operation and settings of:
• Demand meter function
• Station dc monitor function
• Setting group selection function
• Breaker monitor function
• Optoisolated input debounce timers
• SER trigger and alias settings
Section 4: SELOGIC Control Equations describes the operation of:
• SELOGIC Control Equations
• Latch control switches
• General trip logic and generator tripping, with examples
• Close logic
• Synchronism checking function
• Local and remote control switches
• Front-panel display configuration
• Inadvertent energization settings
• Protection alarms
• Relay self-test alarms
• Breaker failure protection
• Tables detailing all Relay Word bits, their definitions and applications
Section 5: Installation describes:
• How to mount and wire the SEL-300G Relay
• Connections for numerous applications
• Explanation of circuit board jumpers
• SEL-300G Relay front- and rear-panel drawings
Section 6: Enter Relay Settings explains:
• How to enter settings via the serial ports or front panel.
• Contains Settings Sheets for general relay, SELOGIC Control Equation, global, SER,
and serial port settings. The Settings Sheets are single-sided and can be photocopied
and filled out to set the SEL-300G Relay. Note that these sheets correspond to the
serial port SET commands listed in Table 6.1.

Introduction and Specifications 1-5
SEL-300G Instruction Manual Date Code 20020206
Section 7: Relay Commissioning describes:
• Commissioning test philosophy and detailed procedure
• Detailed protection element test procedures
Section 8: Monitoring and Metering Functions describes the operation of:
• Generator operating statistics function
• Breaker monitor
• Station dc battery monitor function
• Energy and maximum/minimum metering
Section 9: Front-Panel Operation explains how to enter settings and also contains the
following setting reference information:
• Front-panel target LEDs
• Front-panel pushbuttons and correspondence to serial port commands
• Local control switches (local bit outputs LB1 through LB8)
• Rotating default displays
Section 10: Serial Port Communications and Commands describes:
• Serial port connector pinout/terminal functions
• Communications cables
• Communications protocol
• Serial port commands
Section 11: Event Reports and SER Functions describes:
• Standard 15- and 30-cycle event reports
• Sequential Events Recorder (SER) report
• Synchronism checking reports
Section 12: Maintain and Troubleshoot Relay describes:
• Relay maintenance testing philosophy
• Relay troubleshooting
• Firmware upgrade instructions
Section 13: Differential Element Settings describes:
• Generator differential protection elements
• Logic and operating characteristics
• Settings calculation
Appendices contains the following appendices:
• Appendix A: Firmware Versions
• Appendix B: Differential Connection Diagrams
• Appendix C: SEL Distributed Port Switch Protocol
• Appendix D: Configuration, Fast Meter, and Fast Operate Commands
• Appendix E: Compressed ASCII Commands
• Appendix F: Modbus®RTU Communications Protocol

1-6 Introduction and Specifications
Date Code 20020206 SEL-300G Instruction Manual
SEL-300G Relay Command Summary briefly describes the serial port commands that are
described in detail in Section 10: Serial Port Communications and Commands.
SEL-300G RELAY PROTECTION APPLICATIONS
Complete Generator Primary Protection
When ordered with the optional differential elements, the SEL-300G Relay provides a full
complement of primary protection elements for large machines. The relay is built on the field-
proven SEL-300 Series Relay platform, known for secure, dependable, high-performance
protection.
DWG: M300G028
SEL-387
Unit Differential
SEL-300G1
Primary
SEL-300G0
Backup
Ð
or
Figure 1.1: Large Generator Primary and Backup Protection
In these applications, three- or four-wire potentials and three-phase currents are applied to the
relay for principal protection and metering functions. When differential protection is included,
three additional phase current measurements are required.
Neutral voltage for 100% stator ground protection is taken from the secondary of the grounding
transformer. The SEL-300G Relay neutral voltage input is rated for application up to 300 Vac,
which means that, for most applications, an auxiliary voltage transformer will not be necessary
between the grounding transformer secondary and this relay.
In applications where neutral overcurrent protection is desired, the SEL-300G Relay neutral
current input, IN, may be connected to the secondary of a neutral current transformer. This
transformer may be located in the generator neutral or connected in the secondary circuit of the
grounding transformer. In solidly grounded or resistance grounded applications, the SEL-300G0
and SEL-300G2 Relays offer ground differential (87N) protection.

Introduction and Specifications 1-7
SEL-300G Instruction Manual Date Code 20020206
Feature-Rich Generator Backup Protection
When purchased without the differential elements, the SEL-300G Relay makes a perfect backup
relay for large machines. The relay offers 100% stator ground fault protection, over- and
underexcitation detection, and reverse-power protection in an inexpensive, integrated relay.
Frequency elements, voltage-restrained overcurrent elements, and a host of other elements and
functions round out the package.
DWG: M300G029
SEL-300G0
Unit Backup
SEL-300G3 Unit
Protection Plus
Synch-Check
Ð
or
Figure 1.2: Generator Differential Zone May Include Transformer
Protection for Small- and Medium-Sized Machines
With or without the differential elements, you get large-machine protection, monitoring, and
control that is priced for application on nearly any size machine. The SEL-300G Relay offers
you the freedom to benefit from integrated protection, SER and event reporting, high-accuracy
metering, and breaker and dc monitoring functions without the installation and maintenance
expense of purchasing those components individually.
DWG: M300G030
SEL-300G2
Optional
Synch-Check
Input
Ð
or
Figure 1.3: Simple Protection for Resistance Grounded Generators
In resistance-grounded machine protection applications, 100% stator ground fault coverage may
be obtained by connecting a properly rated voltage transformer to the machine neutral point and
applying the secondary voltage to the SEL-300G Relay neutral voltage input, VN.

1-8 Introduction and Specifications
Date Code 20020206 SEL-300G Instruction Manual
Solidly Grounded Machine Protection
The SEL-300G Relay is suitable to protect solidly grounded machines, with the exception that
the relay does not provide 100% stator ground fault protection for these machines. Phase,
negative-sequence, and neutral overcurrent fault detection methods, plus optional differential
overcurrent protection, are provided. Abnormal operating condition protection, such as loss-of-
field, antimotoring, and overexcitation protection, is also provided.
Thermal Protection of Generator and Prime Mover
The SEL-300G Relay models compatible with SEL-2600 RTD Module (refer to Table 1.2 for
Model Number detail) provide Thermal Protection for the Generator and Prime Mover. The RTD
types and locations are individually configurable. Either ambient temperature or generator load
current can be configured to bias the winding RTD trip temperature thresholds.
SEL-2600 SEL-300G
Relay
Generator Prime
Mover
Fiber-Optic Port
(built into SEL-2600) (SEL-2800 plugged on
to any DB-9 connector)
Up to 500 meters via
single fiber-optic
cable, SEL part
number C801FD
Up to 12 RTD inputs,
plus one contact
DWG: M300G253
Figure 1.4: Generator Thermal Protection with SEL-2600 & SEL-300G Relay
SEL-300G RELAY GENERATOR PROTECTION FEATURES
The SEL-300G Relay offers a full range of elements for generator protection, such as:
• Optional Percentage Restrained Differential Protection (included in SEL-0300G1 and
SEL-0300G3 models)
• Optional 87N Ground Differential Protection (included in SEL-0300G0 and SEL-0300G2
models)
• 100 Percent Stator Ground Detection (for high-impedance and resistance grounded
generators)
• Reverse/Low-Forward Power Elements
• Volts/Hertz Elements for Overexcitation Protection
• Loss-of-Field Protection
• Negative-Sequence Overcurrent Protection
• Voltage-Restrained Phase Time-Overcurrent Elements
• Voltage-Controlled Phase Time-Overcurrent Elements
• Backup Phase Distance Elements
• Neutral Overcurrent Elements
• Under- and Overvoltage Elements for Protection and Control
• Loss-of-Potential Logic

Introduction and Specifications 1-9
SEL-300G Instruction Manual Date Code 20020206
• Optional Synchronism Checking (included in SEL-0300G2 and SEL-0300G3 models)
• Flexible Inadvertent Energization Detection
• Secure Under- and Overfrequency Protection, Plus Off-Fundamental Time Accumulators per
IEEE C37.106 : 1987
• Breaker Failure Protection
• Out-of-Step Protection (single and double blinder schemes)
• Thermal Protection (included in models compatible with SEL-2600 RTD Module).
SEL-300G RELAY ADDITIONAL FEATURES
In addition to the protection functions outlined above, the SEL-300G Relay offers advanced
measuring and monitoring capabilities not found on other generator relays.
• Extensive High-Accuracy Metering Capabilities
• Configurable Front-Panel Display Replaces Separate Panel Meters
• Event Report and SER Reporting
• Advanced SELOGIC Control Equations
• Contact Inputs and Outputs
• Breaker Monitor
• Station Battery Monitor
• Two Independent Setting Groups
CONTACT I/O APPLICATION
Available Contact Input/Output Options
The SEL-300G Relay is available in several hardware configurations. These configurations are
differentiated by the following:
• Chassis size (2U or 3U)
• Mounting type (panel or rack)
• Type of connections at the rear (Screw-Terminal Block or Connectorized®)
• Number of optoisolated inputs
• Number of contact outputs
Relay Models SEL-0300G_0H, SEL-0300G_03, SEL-0300G_WH, and SEL-0300G_W3
The relays listed above provide seven programmable output contacts, plus a self-test ALARM
contact and six optoisolated inputs in a two-rack unit package. All output contacts are rated to
make and carry trip coil current per the requirements of IEEE C37.90 : 1989. These contacts are
not rated to interrupt trip coil current.
Relay Models SEL-0300G_1H, SEL-0300G_13, SEL-0300G_YH, and SEL-0300G_Y3
The relays listed above provide 19 programmable output contacts, plus a self-test ALARM
contact and 14 optoisolated inputs in a three-rack unit package. All output contacts are rated to
make and carry trip coil current per the requirements of IEEE C37.90 : 1989. Seven of the

1-10 Introduction and Specifications
Date Code 20020206 SEL-300G Instruction Manual
output contacts are not rated to interrupt trip coil current. Twelve of the output contacts may be
purchased with high current interruption output contacts for applications requiring up to 10 A
inductive interrupt capability.
Note: High current interrupting output contacts are polarity sensitive. Observe polarity
markings by connecting even-number screw terminals to the higher voltage potential in
the circuit. Do not use high current interrupting output contacts to switch ac control
signals.
High Current Interrupting Output Contacts
SEL-300G Relay purchased with the additional I/O board may be further specified to include
high current interrupting output contacts. These contacts use an integrated-gate bipolar junction
transistor to interrupt contact current in a controlled manner. This increases the contact interrupt
rating, prevents contact arcing, and prevents the inductive voltage spike which occurs when an
inductive current is interrupted by a standard contact.
Refer to the High current interruption option on page 1-17 for detailed specifications of the
high current interrupting output contacts.
Note: High current interrupting output contacts are polarity sensitive. Observe polarity
markings by connecting even-number screw terminals to the higher voltage potential in
the circuit. Do not use high current interrupting output contacts to switch ac control
signals.
Power Supply and Optoisolated Input DC Voltages
The SEL-300G Relay is available in power supply configurations 125/250 V, 48/125 V,
or 24/48 V.
Optoisolated inputs are available with the voltage ratings of 250, 220, 125, 110, 48, or 24 Vdc.
Both the power supply and the optoisolated input voltage ratings are selected when the relay is
ordered. Refer to the Optoisolated Inputs on page 1-18 for detailed specifications.