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. You can 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 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 time-stamped SER reports. You can 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. Configurable labels make it easy 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. With the SEL-451, you get the required substation protection, monitoring, and control in addition to a built-in phasor measurement unit at each substation. The relay makes 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. You can view system state information at the time of faults, or with timed triggers, across the entire system. This system state information helps 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. The acSELerator QuickSet SEL-5030 Software graphical user interface makes it easy to view harmonic analysis and events.

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 up to 103 inputs or 68 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, and 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 SEL-TMU devices 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-451-6 TiDL relay in the control house. Each SEL-TMU can share data with as many as four TiDL relays, providing protection design flexibility and reducing device count. TiDL technology uses point-to-point connections and a non-Ethernet 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 purpose-built SEL-TMU, reducing training requirements, simplifying deployment, and increasing availability. TiDL also provides built-in time synchronization and synchronous sampling, ensuring protection is available in the relay regardless of whether an external time signal is available.

SEL Sampled Values Technology
Implement an SEL SV solution, where the merging unit (publisher) digitizes analog signals from primary equipment and then transmits them to an SEL-451-6 SV relay (subscriber) in the control house via a fiber-based Ethernet network. The system uses precise time synchronization via IRIG-B or PTP. The SEL-451-6 SV relay offers the traditional protection available in the SEL-451-5 and can also receive SV data from devices such as the SEL-401 Protection, Automation, and Control Merging Unit or the SEL-421-7 Protection, Automation, and Control System Merging Unit. Because all SEL SV devices are compliant with IEC 61850-9-2 and the UCA 61850-9-2LE guideline, the SEL-451-6 SV relay can be used with other manufacturers’ SV-compliant units.

Simplified Settings Management
The SEL-451-6 TiDL and SV relays include SEL Grid Configurator, a new configuration software tool that increases efficiency and improves settings insights. It features a spreadsheet-style editor, powerful protection visualization, comprehensive reporting, custom filters, and multiple-device settings management.