html{display:none} SEL-451 Protection, Automation, and Bay Control System | Schweitzer Engineering Laboratories

Innovation, Persistence, and
a New Beginning

A story of the revival of electric power in the Republic of Georgia.

Mother Georgia


Protection, Automation, and Bay Control System

The SEL-451 Protection, Automation, and Bay Control System is a complete standalone system. The SEL-451 has the speed, power, and flexibility to combine complete substation bay control with high-speed breaker protection in one economical system. Use the SEL-451 as an integral part of a full substation protection, control, and monitoring solution. Reduce maintenance costs by accurately tracking the breaker operation. Monitor breaker interruption times and the accumulated breaker duty to easily determine the need for proactive maintenance. Integrate information with SCADA or automation systems through a communications processor or directly to the Ethernet port. Optional Time-Domain Link (TiDL) technology transforms the way you modernize your substation.

Starting At

$4,200 USD

Request a Follow-Up


Dual Breaker Bay Control—Meet your bay control needs with complete two-breaker control and high-speed breaker failure detection. Easily control motor-operated switches, capacitor banks, and field I/O from the front panel or remotely. Use configurable labels to customize relay controls to match your application.

Rapid Bay Control Commissioning—Choose among different bus configurations, including single- and dual-busbar, transfer bus, tie-breaker, breaker-and-a-half, ring-bus, double-bus/ double-breaker, and source-transfer configurations. These bus arrangements allow easy status and control of as many as ten disconnect switches and two breakers.

High-Impedance Fault Detection—Detect high-impedance faults with Arc Sense technology (AST). High-impedance faults are a common result of a downed conductor on surfaces with poor conductivity. With AST, alarm or trip for faults that produce low fault current and are undetectable with conventional overcurrent relays.

Complete Overcurrent Protection—Customize distribution protection with multiple instantaneous and time-overcurrent elements combined with SELogic control equations. Best Choice Ground Directional Element logic optimizes directional element performance and eliminates the need for many directional settings.

Pad-Mounted Switchgear Protection—Protect pad-mounted switchgear with the SEL-451 with low-energy analog (LEA) voltage inputs; this helps to save in overall system cost by eliminating the need for amplification electronics between the line sensor and the relay. Having fewer devices also leads to a simpler system, a reduction in labor costs, and elimination of a possible point of failure.

Breaker Wear Monitoring—Compare published data of the breaker’s manufacturer to the actual interrupted current and number of operations for two breakers, and create alarms accordingly. Monitor mechanical and electrical interruption time per pole, comparing average and last trip times for maintenance scheduling.

TiDL Technology—Modernize your substation by applying the TiDL-enabled SEL-451 with the SEL-2240 Axion TiDL nodes. In a TiDL system, the Axion node provides remote I/O and digitizes analog signals over fiber optics for the relay. This simple and secure digital secondary system solution is easy to implement, with no external time source or network engineering required. Replacing copper with fiber increases safety, reduces costs associated with using copper, improves reliability, and limits the impact of an electromagnetic pulse.

Fast Motor Bus TransferPreserve process reliability with the SEL-451 multifunction Fast Motor Bus Transfer System, which switches the motor bus to an alternate source before the motor slows down. The Fast Motor Bus Transfer System includes all transfer modes (fast transfer, in-phase transfer, and residual transfer) in one low-cost SEL-451 package. Learn more.



Overview—TiDL Technology Rear Panel


Transformer Inrush Harmonic Monitoring
Apply the second-, fourth-, and fifth-harmonic elements with individual threshold settings to detect transformer energization and overexcitation conditions. The output from these harmonic detection elements can be used for a variety of functions, including modification of relay settings to improve security and event reporting to make identification of transformer energization events fast and simple.

Built-In Web Server
Access basic relay information on a standard Ethernet network with the built-in web server. View relay status, Sequential Events Recorder (SER) information, metering information, and settings with easy access within a local network. The web server access requires a relay password and is limited to read-only viewing of information.

Simple Network Time Protocol (SNTP)
Simplify wiring and installation by receiving a time signal over existing Ethernet networks. SNTP makes a good backup to more accurate IRIG-B time synchronization. The 5 ms accuracy is good for basic time synchronization throughout a substation.

Maximize the Capability of Substation Equipment
Fully load equipment by monitoring power, including thermal or rolling interval demand as well as peak demand on positive-, negative-, and zero-sequence current. Use the full capacity of the equipment while maintaining SEL quality protection.

Advanced Visualization Tools
The SEL-451 offers a configurable human-machine interface (HMI) for easy integration into your application or operating standards. HMI tools include custom metering and status displays, direct pushbutton access, critical information alarms in chronological order, a rotating display, and timestamped SER reports. Reduce errors by automatically scrolling between one-line bay diagrams, custom metering displays, and alarms.

Bay Control for Two Breakers
Complete two-breaker control and breaker failure complement the versatility of the SEL-451 programmable logic to meet your bay control needs. Easily control motor-operated switches, capacitor banks, and field I/O from the front panel or remotely. Use configurable labels to customize relay controls to match your application.

Flexible Communications

  • An Ethernet card option provides two copper or fiber ports for failover redundancy.
  • Simplify Ethernet network topology and reduce external equipment with dual Ethernet ports that offer a switched mode for looped Ethernet networks.
  • Available Ethernet communications protocols include FTP, Telnet DNP3, LAN/WAN, the IEEE 1588 Precision Time Protocol Version 2 (PTPv2), IEC 61850 Edition 2, IEEE C37.118 synchrophasors, and the Parallel Redundancy Protocol (PRP).
  • All four independent EIA-232 serial ports support enhanced SEL Mirrored Bits communications, SEL Fast Message, SEL ASCII, Compressed ASCII, SEL Fast Operate, SEL Fast Meter, SEL Fast SER, and DNP3 Level 2 Slave.

Improve Operation With IEEE Synchrophasor Data
Give operators critical system information via serial or Ethernet communications. Install required substation protection, monitoring, and control using the SEL-451, and get a built-in phasor measurement unit at each substation. Make control decisions based on voltage, current, or frequency data from other relays. The synchrophasor real-time control (RTC) capability makes this information available for local or system-wide control and automation.

High-Accuracy Timestamping
Time-tag binary COMTRADE event reports with real-time accuracy of better than 10 µs. View system state information at the time of faults, or with timed triggers, across the entire system. Use system state information to validate system models and improve transfer limits and system stability.

Digital Fault Recording (DFR)
Combine relaying reliability with true DFR functionality. The SEL-451 Relay’s high-speed sampling (8 kHz) and COMTRADE output provide advanced oscillography. Use the acSELerator QuickSet SEL-5030 Software graphical user interface for harmonic analysis and easy event viewing.

Integrate Many Substation Devices Into One Powerful System Using the SEL-451
Control cooling fans, motor-operated switches, or other equipment using the processing and I/O of the SEL-451. Hardware options let you expand I/O to 55 inputs and 24 outputs.

Expanded SELogic Control Equations
Use math and logic combinations of analog and digital values for customized applications. Adapt system control based on prefault conditions. Scale analog values and latch momentary inputs for SCADA retrieval.

acSELerator QuickSet Software
Help speed up relay applications by developing relay settings offline, programming SELogic control equations, and analyzing post-fault event reports.

Voltage Sag, Swell, and Interruption (VSSI) Report
Capture power quality data related to voltage disturbances over a long period of time.

Time-Domain Link Technology
Apply a TiDL solution, where Axion TiDL nodes are placed in the yard close to the primary equipment to digitize discrete I/O signals and analog data and then transport them over a fiber-optic cable to the SEL-451 in the control house. This innovative technology uses point-to-point connections and a nonroutable protocol, providing a simple and secure solution. Because it does not need an external time source or Ethernet switches, it is easy to implement with no network engineering required. TiDL combines the proven protection of the SEL-400 series relays with the modularity of the Axion, reducing training requirements and providing a scalable and flexible solution. It also provides built-in time synchronization and synchronous sampling, ensuring protection is available in the relay regardless of whether or not an external time signal is available.

  • Rack- or panel-mount horizontal or vertical hardware packages.
  • Ethernet connection options for primary and standby connections:
    • 10/100BASE-T
    • 100BASE-FX
  • IEC 61850 Edition 2 communications and IEEE 1588 Precision Time Protocol Version 2 (PTPv2).
  • 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.
  • Connectorized hardware configuration.
  • Enhanced HMI with 24 target LEDs and 12 operator pushbuttons.
  • Independent breaker trip/close pushbuttons with status indication, including 24 additional input and 4 additional output contacts.
  • High-impedance fault detection using Arc Sense technology.
  • Conformal Coating: Protect equipment from harsh environments and airborne contaminants, such as hydrogen sulfide, chlorine, salt, and moisture.


Documents sorted by newest first.




Minimum QuickSet Version

Minimum QuickSet Version

Product Certifications