html{display:none} SEL-551C Overcurrent/Reclosing Relay | Schweitzer Engineering Laboratories


Overcurrent/Reclosing Relay

The SEL-551C Overcurrent/Reclosing Relay provides overcurrent relay users with new flexibility in distribution system protection. The SEL-551C provides six inputs and three outputs, with up to two communications ports, for more control options. The SELogic control equations have added rising and falling edge triggers and latches for custom logic applications. 

SEL-551/SEL-551C and SEL-851 Comparison


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Asset Protection—Monitor and protect distribution feeders, distribution buses, transformers, capacitors, or circuit breakers.

Current Transformer (CT) Connection Versatility—Connect the separate neutral-current input to accommodate core-balance CTs, separate neutral CTs, tertiary-winding CTs, or CT ground-residual circuits.

Reclosing Control—Coordinate with downstream reclosers using sequence coordination logic to program up to four reclosing attempts.

Integration—Integrate into protection and control schemes with the Modbus RTU protocol. The optional front-panel EIA-232 port on the SEL-551C allows easy connection, even while communicating on the rear port.


Complete Overcurrent Protection
Protect lines and equipment using a sensitive and secure mix of phase, negative-sequence, and ground overcurrent elements. Provide high-speed operation, even with severe CT saturation, using the SEL Adaptive Overcurrent Element.

acSELerator QuickSet SEL-5030 Software
QuickSet helps speed up the relay application by allowing you to develop relay settings offline, program SELogic control equations, and analyze post-fault event reports.

Field-Proven Hardware With Optional Features
The six inputs and three outputs are fully programmable to meet your application needs. A wide operating temperature range (–40° to +85°C) allows for installation in a control house or outdoor enclosure.

Advanced Programmable Logic and Local/Remote Controls
Configure traditional or advanced protection and control schemes. Use edge- triggers or latches within the SELogic control equations for advanced control.

  • Panel-mount or rack-mount hardware package.
  • Rear port EIA-232 or EIA-485 serial communications; ports include a demodulated IRIG-B time-code input.
  • Optional front EIA-232 port provides easy access to relay settings and reports, even when rear port is configured as EIA-485 Modbus RTU.
  • Use synchroWAVe Event 2015 Software to display oscillograms and vector diagrams to analyze event reports.
  • Use acSELerator Team SEL-5045 Software to automatically gather relay event reports on your PC and manage them with a database.
  • Conformal Coating: Protect 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-551C R505 SEL-551C-R505-Vf-Z001001-D20110408 4/14/11 1111040001

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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501 551 551C 587Z - Software Tab


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 SEL-5030 software page.

Visualization & 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 SEL-5601-2 software page.

Product Certifications