SEL-311L

The SEL-311L is a powerful line current differential relay designed for high-speed protection of transmission lines, distribution feeders, and underground cables. It uses secure digital communication channels to compare real-time currents from line ends, providing ultra-fast fault isolation. The relay includes distance protection, pilot schemes, load encroachment logic, and advanced fault locating capabilities. Its redundant communication options (fiber, multiplexers, SDH/SONET, Ethernet) ensure robust channel performance. The SEL-311L integrates seamlessly into modern digital substations with IEC 61850 GOOSE messaging and PRP/HSR redundancy. With a durable design proven in harsh environments, it offers dependable protection for critical transmission assets.

Key Features

• High-speed line differential protection

• Distance protection (21) backup

• Multiple communication channel redundancy

• High-accuracy fault locator

• IEC 61850, GOOSE, PRP/HSR

• Reclosing, synch check, and load encroachment

Applications

• Transmission and sub-transmission lines

• Underground cable circuits

• Pilot protection schemes

• Long-line differential protection

Keywords

SEL-311L, line differential relay, transmission line protection, IEC 61850 line relay