Schweitzer Engineering Laboratories

Innovation is the heart of SEL. Inspired by his research as a doctoral candidate, Dr. Schweitzer invented the first microprocessor-based digital protective relay, the SEL-21, which revolutionized the electric power industry and provided new functionality in power system protection. He made his first sale to Otter Tail Power Company in 1984. The grit, passion, and creativity that drove SEL from a basement with a handful of employees to a worldwide company with over 5,000 employees continue to be a driving force and source of inspiration today.