html{display:none} SEL-351 Protection System | Schweitzer Engineering Laboratories


Protection System

The SEL-351 Protection System has built-in Ethernet and IEEE C37.118 synchrophasors, and is ideal for directional overcurrent applications. Optional Mirrored Bits communications and power quality monitoring add flexibility to solutions. The SEL-351 is the protection standard for utility and industrial electrical systems around the world.

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Breaker Failure Detection—Detect a failed circuit breaker quickly with built-in fast-reset breaker failure detection elements and logic.

Pilot Protection Schemes—Apply pilot protection on transmission, subtransmission, or distribution circuits, including three-terminal lines with traditional pilot communications equipment or with optional Mirrored Bits communications.

Grounded Power System Protection—Apply sensitive directional overcurrent protection for Petersen Coil grounded, ungrounded, and impedance-grounded power systems.

Service Restoration—Dispatch line crews to quickly isolate overhead line problems and restore service faster using the built-in fault locator.

Enhanced Circuit Breaker Monitoring—Schedule circuit breaker maintenance based on need as determined from detailed breaker monitoring data and alarms.

  • Integrate and automate substation equipment, even devices from multiple vendors, with the IEC 61850 communications protocol.
  • Protect and control radial or looped transmission, subtransmission, or distribution circuits.
  • Use pilot protection on transmission or subtransmission circuits, including three-terminal lines.
  • Apply directional and nondirectional overcurrent protection for a transformer/bus-main/bus-tie breaker.
  • Protect and control capacitor banks.
  • Apply breaker failure protection.
  • Control autoreclosing with synchronism and voltage check logic.
  • Protect small generators.
  • Protect distributed generation interconnections.
  • Shed load using underfrequency elements.
  • Add fault indicators to distribution protection, and reduce fault-finding time by 50 percent.
  • Dispatch line crews to quickly isolate overhead line problems and restore service faster using the built-in fault locator.
  • Schedule circuit breaker maintenance based on need as determined from breaker-monitoring data and alarms.
  • Analyze overcurrent protection system performance using the built-in Sequential Events Recorder (SER).
  • Use acSELerator QuickSet SEL-5030 Software to manage your relay settings.
  • Use acSELerator Team SEL-5045 Software to automatically gather relay event reports on your PC and manage them with a database.
  • Use synchroWAVe Event Software to display oscillograms and vector diagrams to analyze event reports.


    1. 1

      USB port simplifies local connections and speeds up relay communications

    2. 2

      Default displays or programmable custom messages notify personnel of power system events or relay status

    3. 3

      Front-panel LEDs alert operators in the substation to faulted phases, the relay’s status, and element operation

    4. 4

      Optional SafeLock® trip/close pushbuttons and bright indicating LEDs allow breaker control independent of the relay

    1. 1

      High-current interrupting output contacts increase contact robustness and reliability

    2. 2

      Expanded I/O allows for flexible applications

    3. 3

      Harmonic metering to the 16th harmonic enhances power quality analysis

    4. 4

      Dual copper Ethernet port allows communication between devices and provides redundancy. Single or dual fiber-optic ports are also available.

    5. 5

      Standard multisession Modbus® TCP, Modbus RTU, DNP3, and IEC 61850* provide communications flexibility

    6. 6

      Mirrored Bits® communications provides fast and reliable relay-to-relay communication

    7. 7

      EIA-485 port provides quick and easy engineering access

    8. 8

      SafeLock® trip/close pushbuttons on the front panel are wired directly to these terminals to allow breaker control independent of the relay

    9. 9

      Sensitive earth fault (SEF) protection accurately detects ground faults with low current values

    10. 10

      Built-in phasor measurement unit allows wide-area power system monitoring



  • IEC 61850 communications protocol
  • Front-panel USB communications port
  • SafeLock independent trip/close pushbuttons
  • Dual copper or single or dual fiber-optic Ethernet ports
  • Rack, panel, and projection mounting
  • 2U and 3U enclosure heights
  • Horizontal and vertical orientations
  • Mirrored Bits communications and load profiling
  • Additional I/O board with contact-sensing inputs and standard or high-current interrupting contact outputs
  • Sensitive directional power elements
  • Voltage sag, swell, and interruption recording
  • Low-range neutral current input channel for nondirectional sensitive earth fault (SEF) applications
  • Low-range neutral current channel for directional control for Petersen coil-grounded, high-impedance-grounded, or ungrounded power systems
  • Conformal coating—Protects equipment from harsh environments and airborne contaminants, such as hydrogen sulfide, chlorine, salt, and moisture

Minimum Software Version

Latest Firmware Versions

There are no firmware versions available for this product.

Product Revision Firmware ID Date Available Serial Number
SEL-351-5 R518-V1 SEL-351-5-R518-V1-Z107106-D20210917 9/28/21 ~1212710001 or ~3212710001
SEL-351-6 R518-V1 SEL-351-6-R518-V1-Z107106-D20210917 9/28/21 ~1212710001 or ~3212710001
SEL-351-7 R518-V1 SEL-351-7-R518-V1-Z107106-D20210917 9/28/21 ~1212710001 or ~3212710001

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.

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.

Visualization and Analysis

SEL-5601-2 synchroWAVe Event Software

synchroWAVe Event helps engineers diagnose a protective relay’s behavior during a power system fault. It is a powerful and easy-to-use solution for displaying and analyzing SEL relay event reports and COMTRADE files.

Learn more and download on the synchroWAVe Event software page.

Product Certifications