Our History

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.

Timeline of Events

1982

Dr. Schweitzer founds Schweitzer Engineering Laboratories with the invention of the SEL-21, the first relay to use microprocessor-based computation and algorithms.

1984

SEL makes its first sale to Otter Tail Power Company in Fergus Falls, Minnesota, as a company of seven working out of Dr. Schweitzer’s basement.

1992

SEL grows to 100 employees.

1994

SEL implements the employee stock ownership plan (ESOP).

1997

We release the SEL-351, which became the benchmark for protective relay standards in North America.

1998

SEL begins offering engineering consulting, testing, and design through our Engineering Services team.

2000

We introduce our unprecedented ten-year, worldwide product warranty—the best in the industry.

2001

SEL establishes Government Services to serve government customers.

2003

SEL opens a site in Monterrey, Mexico, to manufacture high-quality panels for our customer Comisión Federal de Electricidad.

2004

SEL acquires E. O. Schweitzer Manufacturing in Mundelein, Illinois, which was started by Dr. Schweitzer’s father, Edmund O. Schweitzer, II.

2009

SEL becomes 100 percent employee-owned.

2012

SEL opens a manufacturing facility in Lewiston, Idaho.

We kick off the first year of our Modern Solutions Power Systems Conference, which encourages cross-disciplinary discussion of common challenges and success stories relating to electric power and promotes idea generation to drive innovation.

2016

We introduce the SEL-T400L Time-Domain Line Protection, the fastest relay in the world.

2019

SEL President and Chief Technology Officer Dr. Edmund O. Schweitzer, III, is inducted into the National Inventors Hall of Fame for his invention of the microprocessor-based digital protective relay.

2020

We open the doors to our fifth manufacturing facility, next to Purdue University in West Lafayette, Indiana. The site’s proximity to Purdue University allows close research collaboration between the two entities.