Our Roots
Edmund O. Schweitzer, III founded SEL in 1982 in Pullman, Washington. The company introduced the world’s first digital protective relay to the electric power industry in 1984. This same year, Otter Tail Power Company in Fergus Falls, Minnesota, became SEL’s first customer. The first SEL digital relay, the SEL-21, revolutionized the power protection industry by providing fault locating and real fault data at a much lower cost to the customer than traditional electromechanical relays. With the introduction of the load-encroachment element for feeder protection, synchrophasors as a standard feature in protective relays, and Mirrored Bits® relay-to-relay communications, SEL continues to set the technology curve.
SEL became an employee-owned company in 1994 and transitioned to 100 percent employee ownership in 2009. With over 3,000 employees around the world, SEL continues to grow in its capacity for innovation and customer support.
E. O. Schweitzer Manufacturing
In 1950, after presenting ideas and prototypes to Commonwealth Edison in Chicago, Edmund O. Schweitzer, Jr. founded E. O. Schweitzer Manufacturing to design and manufacture line-powered fault indicators. A division of SEL since 2005, the company started by SEL founder Edmund O. Schweitzer, III’s father today supplies utilities around the world with fault indicators and sensors that reduce faultfinding time and quickly restore power after a fault occurs and is known as the Fault Indicator and Sensor Division of SEL.
EOS Manufacturing has sold millions of high-quality fault indicators, voltage indicators and sensors, and split-core current transformers to over 1,000 domestic and international customers. With advances in sensor technology, including radio frequency fault indication solutions for both underground and overhead applications, the Fault Indicator and Sensor Division of SEL continues to find innovative ways to reduce fault-finding time.
Combined with SEL protective relays and recloser/voltage regulator controls, fault indicators and sensors are an integral part of SEL’s ability to improve the reliability of electrical distribution systems. As power quality becomes increasingly important, more customers realize the tremendous potential of fault indicators to reduce customer outage time—and even reduce the number of outages, in some cases. The result is that customers experience fewer, shorter outages, and utilities’ SAIDI, CAIDI, and SAIFI reliability metrics improve.