html{display:none} SEL-400G Advanced Generator Protection System | Schweitzer Engineering Laboratories


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.

Starting At

$12,000 USD

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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, IEC 62439 PRP, Mirrored Bits communications, Modbus, DNP3, and other protocols.


    1. 1

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

    2. 2

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

    3. 3

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

    4. 4

      Easy-to-use keypad aids simple navigation

    5. 5

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

    6. 6

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

    1. 1

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

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      Communications protocols include FTP, Telnet, synchrophasors, DNP3 LAN/WAN, the Parallel Redundancy Protocol (PRP), IEC 61850 Edition 2, and the IEEE 1588 Precision Time Protocol Version 2 (PTPv2). For PTPv2 implementation, Ports 5A and 5B must be ordered as an option.

    3. 3

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

    4. 4

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

    5. 5

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



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.

Easy Communications

Quickly integrate the SEL-400G into serial- or Ethernet-based communications with IEC 61850, IEC 62439 PRP, Mirrored Bits communications, Modbus, DNP3, and other protocols.

RTD-Based Thermal Protection

Use as many as two external SEL-2600 RTD 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.

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.

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

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