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Advanced Generator Protection System

The SEL-400G offers primary and backup protection for generators of all sizes and types, including hydro, pumped-storage hydro, steam turbine, and combustion gas turbine generators. It combines generator, bus, and step-up transformer protection in one package, making the relay an economical solution for an entire generation unit.

Advanced protection functions, like transverse differential protection, provide turn-to-turn fault detection, which allows for earlier fault detection, limits damage to your generator, and helps you return to service faster. Adaptive differential protection and a wide frequency tracking range (5–120 Hz) improve protection security. Dual frequency zones and autosynchronization offer smooth synchronization to the grid.

You can quickly integrate the SEL-400G into serial- or Ethernet-based communications. The new SEL Grid Configurator software allows you to quickly create, manage, and deploy device settings. Or, you can continue to use acSELerator QuickSet SEL-5030 Software for your configuration needs.

SEL-400 Series Relay Mimic Diagrams

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Advanced Generator Protection—Two independent universal differential elements provide protection for the generator and GSU transformer in a single relay. With its 18 current inputs, 6 voltage inputs, and wide-range frequency tracking (5–120 Hz), the SEL-400G can be applied in a wide variety of generator configurations. In addition, its advanced antimotoring protection and loss-of-field protection elements further protect your generator.

Pumped Storage Logic—This feature enables pumped storage hydropower protection without the need for external relays to switch CT wiring, which lowers costs and improves reliability.

Stator Ground Fault Protection—Achieve passive and active ground fault detection across 100 percent of the stator winding. The stator winding ground fault protection elements include integrating timers that detect intermittent ground faults and isolate the generator before the fault evolves into a permanent fault.

Rotor/Field Winding Protection—Applying the SEL-2664 Field Ground Module and the SEL-2664S Stator Ground Protection Relay with the SEL-400G allows you to protect your system against rotor/field winding short circuits. With the field ground protection element, the first fault will trigger an alarm and a second fault results in a trip signal. This allows you to continue meeting your generating obligations and to schedule an outage at a preferred time. 

Simplified Settings Management—SEL Grid Configurator is a new configuration software tool that increases efficiency and improves settings insights. It features a spreadsheet-style editor, powerful protection visualization, comprehensive reporting, custom filters, and multiple-device settings management.

Communication and Integration—Quickly integrate the SEL-400G into serial- or Ethernet-based communications with IEC 61850, the IEC 62439 Parallel Redundancy Protocol (PRP), Mirrored Bits communications, Modbus, DNP3, and other protocols. Use small form-factor pluggable (SFP) transceivers on designated process bus, station bus, and engineering access ports in the five-port Ethernet card. Choose between single- and multimode communications options for increased flexibility.


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      EIA-232 front serial port is quick and convenient for system setup and local access.

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      Front-panel display allows operators to control and view the status of disconnects and breakers.

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      User-selectable mimic screens show the system configuration in one-line diagram format.

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      Easy-to-use keypad aids simple navigation.

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      Front-panel, tricolor LEDs indicate custom alarms and provide fast and simple information to assist dispatchers and line crews with rapid power restoration.

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      Programmable operator pushbuttons with user-configurable labels allow front-panel customization.

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      Choose from a horizontal panel-mount or rack-mount chassis.

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      Communications protocols include FTP, Telnet, synchrophasors, Modbus TCP, DNP3 LAN/WAN, PRP, IEC 61850 Edition 2, and the IEEE 1588 Precision Time Protocol Version 2 (PTPv2). Select a five-port Ethernet card for dedicated process bus, station bus, and engineering access ports.

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      Use three rear EIA-232 ports for Mirrored Bits communications, DNP3, SCADA, and engineering access.

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      Power supply options include: 24–48 Vdc; 48–125 Vdc or 110–120 Vac; or 125–250 Vdc or 110–240 Vac.

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      The 18 current and 6 voltage channels can be configured for a variety of applications.

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      The relay can be ordered with up to an 8U chassis that can accommodate as many as three I/O boards with a wide range of input and output combinations



Advanced Generator and Unit Protection
Increase machine life by detecting faults and abnormal conditions before they cause permanent damage. The 18 current and 6 voltage inputs on the SEL-400G enable complex generator protection schemes or protection of other equipment, such as transformers. 

Wide-range Frequency Tracking
The wide-range frequency tracking (5 to 120 Hz) ensures that all protection functions are secure and dependable across a wide range of system frequencies or generator speeds. This provides protection during events such as unit overspeed or inverter-driven startup.

The built-in automatic synchronizer function eliminates the need for expensive external synchronizer equipment. The SEL-400G automatically synchronizes frequency, voltage, and phase control and connects the generator to the power system.

RTD-Based Thermal Protection
Use as many as two external SEL-2600 modules to acquire thermal data for alarm, monitoring, and trip functions in the SEL-400G.

Metering and Reporting
View generator autosynchronizer, Sequential Events Recorder (SER), and various event reports in COMTRADE format to analyze generator startup, shutdown, or system faults. Measure electrical, thermal, and generator run-time quantities and retrieve COMTRADE files via Ethernet FTP or IEC 61850 MMS.

Synchrophasor Data
Apply SEL synchrophasors (IEEE C37.118) to turn state estimation into state measurement and to provide early warning of potential system instability. The SEL-400G phasor measurement accuracy complies with IEEE C37.118.1/2-2011, -2014a.

Flexible Ethernet Communications
The four- and five-port Ethernet communications card options enable you to communicate using a variety of protocols, including FTP, HTTP, DNP3, PTPv2, PRP, Telnet, synchrophasors, and IEC 61850 Edition 2.

The SEL-400G can be configured with a five-port Ethernet card supporting PRP or failover functionality to increase system availability, as well as the Precision Time Protocol Version 2 (PTPv2) on process bus or station bus ports for time synchronization. Use network monitoring features in the relay to further improve system availability by actively monitoring each redundant path to detect communications network failures.

The five-port card also features dedicated ports and IP addresses for station bus and engineering access networks to provide selective access control. All ports support SFP transceivers. Single- and multimode communications options provide increased flexibility. All ports support 100 Mbps SFP transceivers, and process bus ports also support 1 Gbps SFP transceivers.

Serial Communications
All four independent EIA-232 serial ports support SEL ASCII, Compressed ASCII, SEL Fast Operate, SEL Fast Meter, SEL Fast SER, enhanced SEL Mirrored Bits communications, Ymodem, and DNP3 Level 2 Outstation as well as dial-out, Virtual Terminal, and communications with SEL-2600 series RTD modules.

Multiple Configuration Platforms
The SEL-400G can be configured, commissioned, and managed using either SEL Grid Configurator or QuickSet. Select the choice that best fits your application and software transition needs.

Minimum Software Version


Advanced Generator Protection—SEL-400G

Latest Firmware Versions

There are no firmware versions available for this product.

Product Revision Firmware ID Date Available Serial Number
SEL-400G R105-V0 SEL-400G-R105-V0-Z006002-D20240529 6/8/24 ~1241600001
SEL-400G-1 R105-V0 SEL-400G-1-R105-V0-Z006002-D20240529 6/8/24 ~1241600001

The Firmware IDs for older versions of the firmware can typically be found in Appendix A of the instruction manual.

Minimum Software Version

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Configuration Software

acSELerator QuickSet SEL-5030 Software

QuickSet is a tool for engineers and technicians to quickly and easily configure, commission, and manage power system devices. QuickSet includes a Graphical Logic Editor and a device template tool to reduce configuration time and streamline deployment.

Learn more and download on the QuickSet software page.

SEL-5037 Grid Configurator Software

SEL Grid Configurator is a no-charge software tool for engineers and technicians to create, manage, and deploy settings for SEL power system devices.

Learn more and download on the Grid Configurator software page.

SEL-5032 acSELerator Architect SEL-5032 Software

Architect allows users to configure and document IEC 61850 systems that include GOOSE, Sampled Values (SV), or Manufacturing Message Specification (MMS) communications. Architect automatically compares SCL files with IEC 61850 requirements to ensure standard compliance.

Learn more and download on the Architect software page.

Automated Data Collection

SEL Data Management and Automation (DMA) Application Suite

Available on the Blueframe platform, DMA applications automatically collect, store, and manage device-specific information like oscillography, Sequence of Events (SOE) data, device settings, and property information. They also provide automated password rotation and streamlined device audits.

Learn more on the DMA software page.