Feeder Protection Applications
The SEL-851 relay’s overcurrent functions protect power system circuits or devices, including lines, feeders, transformers, and capacitor banks. Over- and underfrequency and over- and undervoltage elements are well suited for applications at distributed generation sites. The relay’s directional power elements also make the SEL-851 suitable for utility or customer interface protection where customer generation is present. In addition, you can use the relay’s powerful SELogic control equations to provide custom protection and control applications.

Simplified Design
The SEL-851 is built with high-reliability hardware and comes with a universal power supply, setting-selectable universal current inputs (1 A/5 A), and optional software-selectable binary inputs (24–250 Vac/Vdc). Its simplified design helps reduce expenses.

Fast, Deterministic Relay-to-Relay Communications
Achieve fast, deterministic relay-to-relay communications using fixed GOOSE messaging. It provides ease of programming and offers the flexibility of multidevice communication of digital and analog quantities at a fixed 4 ms rate.

Integrated Web Server
The built-in web server enables secure, remote access to the relay with password protection. You can download status reports or view metering and relay information remotely. You can also safely read, edit, save, and download relay settings. This helps minimize trips to the relay location, saving time and money. The web server also enables firmware upgrades.

Operator Controls
Increase operator safety during commissioning and testing using the Local/Remote pushbutton control on the relay’s front panel. Perform breaker control using the Trip and Close pushbutton controls.

Metering and Monitoring
The SEL-851 relay’s built-in metering function allows you to eliminate separately mounted metering devices. Analyze Sequential Events Recorder (SER) reports and oscillographic event reports for rapid commissioning, testing, and post-fault diagnostics.

Signal Profiling
Signal profile monitoring provides a periodic snapshot (selectable rate of every 5, 10, 15, 30, or 60 minutes) of as many as 16 selectable analog quantities. The relay maintains signal profile information in nonvolatile buffer memory, which can hold as many as 4,000 time-stamped entries.

Relay Management and Diagnostics

• The Data Management and Automation (DMA) Application Suite on the SEL Blueframe platform is designed to automatically collect, store, and manage device-specific information to simplify day-to-day management of your system of devices and to support compliance. The DMA Diagnostics application provides SEL-851 status updates and detailed logs that help you monitor the relay’s health and quickly identify communications issues.
• SEL-5601-2 synchroWAVe Event Software helps you diagnose a protective relay’s behavior during a power system fault. It is a powerful yet easy-to-use solution for displaying and analyzing SEL relay event reports and COMTRADE files.

Rugged Hardware
Trust the industry’s widest ambient operating temperature range, –40° to +85°C (–40° to +185°F). The plastic chassis SEL-851 withstands vibration, electrical surges, fast transients, and extreme temperatures, meeting stringent industry standards. A conformal-coating option for the printed circuit boards provides an additional barrier to airborne contaminants, such as hydrogen sulfide, chlorine, salt, and moisture.