SEL-451 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.

  • Feeder protection
  • Dual-breaker bay control and breaker wear monitoring
  • Feeder protection
  • Dual-breaker bay control and breaker wear monitoring
  • High-impedance fault detection
  • Comprehensive communications protocol, including IEC 61850 Edition 2 and additional I/O
  • TiDL-enabled relay for a digital secondary system (see all available topologies in the Quick-Start Guide)
  • Eight fiber ports (to connect to SEL-2240 Axion TiDL nodes) in place of the current and voltage analog inputs
  • Feeder protection
  • Dual-breaker bay control and breaker wear monitoring
  • Additional high-speed, high-current interrupting Form A outputs for high-speed tripping
  • Comprehensive communications protocols, including IEC 61850 Edition


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.