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Protection, Automation, and Control Merging Unit

Apply the SEL-401 Protection, Automation, and Control Merging Unit for substations with IEC 61850-9-2 Sampled Values (SV) systems. Sample analog data, such as currents and voltages, then publish those data to a fiber-based Ethernet network for use in other IEDs, such as compliant SEL-400 series relays. The SEL-401 publishes SV data to the process bus network and also provides local protection. Use the built-in phase-overcurrent and breaker failure protection to provide backup in case of communications system failures.

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Starting At

$5,190 USD

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IEC 61850-9-2 SV Implementation—Place the SEL-401 out in the yard right next to primary equipment. The SEL-401 digitizes analog signals from primary equipment and then transmits them to the control house via a fiber-based Ethernet network. It can publish as many as seven outgoing data streams of IEC 61850-9-2 SV data to any relays that subscribe to SV. The merging unit can synchronize the data using the IEEE 1588 Precision Time Protocol Version 2 (PTPv2) or an IRIG-B time input.

Integrated Protection—Provide local breaker failure and phase overcurrent protection during a loss of the precise time signal or communication to a main substation relay. The SEL-401 uses high-speed (5/8-cycle) open-pole detection logic to reduce coordination times for critical breaker failure applications.

Dual-Breaker Schemes—Accommodate two sets of three-phase currents and two sets of three-phase voltages to support substations with dual-breaker schemes. You can combine currents within the merging unit from two sets of CTs for protection functions but keep them separately available for monitoring and station integration applications.

Oscillography—Record voltages, currents, and internal logic points at up to an 8 kHz sampling rate. Phasor and harmonic analysis features allow the investigation of merging unit and system performance.

Sequential Events Recorder (SER)—Record the last 1,000 entries, including setting changes, when the merging unit turns on, and selectable logic element operations.


401 front callouts401 back callouts

SEL SV Technology
Implement an SEL SV solution, where the SEL-401 digitizes analog signals from primary equipment and then transmits them to an SV intelligent electronic device (IED), such as an SV-capable SEL-400 series relay, in the control house via a fiber-based Ethernet network. This removes high-energy copper cables from the control house, leading to cost savings and increased safety. The SV system uses precise time synchronization via IRIG-B or PTP.

The SEL-401 is the only standalone merging unit in the world with built-in phase overcurrent and breaker failure protection. This allows you to have the protection right next to the primary equipment for increased speed and reliability, as well as to easily duplicate the SV data streams for redundant protection.

Because all SEL SV devices are compliant with IEC 61850-9-2 and the UCA 61850-9-2LE guideline, the SEL-401 can work with primary equipment that generates similar SV streams or with other manufacturers’ SV-compliant units.

Self-Test Capabilities
The SEL-401 merging unit’s self-test capability, which consists of simulating SV network traffic, allows you to verify network connections between SEL SV devices during commissioning or testing.

Automation and Control
Take advantage of SELogic control equations with math and comparison functions for control applications.

The SEL-401 includes 32 programmable elements for enhanced automation features regarding local control, remote control, protection latching, and automation latching.

Serial and Ethernet links let you efficiently transmit key information, such as metering data, IEEE C37.118 synchrophasors, SER reports, breaker monitoring, merging unit summary event reports, and time synchronization.

Metering and Monitoring
Employ extensive metering capabilities, such as instantaneous metering, power/energy metering, and comprehensive reporting of SV communications streams. Event reports and the SER log provide valuable time-stamped information for commissioning and post-event analysis.

Provide real-time system state measurement with time-synchronized voltages and currents in the IEEE C37.118 standard format. Combined with SEL-5078-2 synchroWAVe Central Software or third-party software, this enables you to view and analyze system phase angles, load oscillations, voltage profiles, and other critical system information.

  • Rack- or panel-mount, horizontal and vertical hardware packages.
  • Ethernet connection options for primary and standby connections.
    • 10/100BASE-T
    • 100BASE-FX
  • One or two additional I/O boards with standard, high-interrupting or high-speed/high-interrupting outputs.
  • User-configurable labels for operator controls and target LEDs.
  • Conformal Coating protects equipment from harsh environments and airborne contaminants, such as hydrogen sulfide, chlorine, salt, and moisture.

Minimum QuickSet Version

Product Revision Z Number Minimum Software Version
SEL-401 R403-V0 101
SEL-401 R402-V0 100
SEL-401 R400-V1 100
SEL-401 R400-V0 100