What is SEL in electrical engineering?

SEL manufactures protective relays that detect abnormal power system conditions and initiate protective actions like opening circuit breakers to prevent equipment damage.

Where are SEL relays used?

Electric utility substations, transmission lines, distribution feeders, generating stations, and industrial power systems including refineries, data centers, and manufacturing facilities.

What Is SEL? Introduction to Schweitzer Engineering Laboratories

Q: Are SEL instruction manuals free?

Yes. SEL publishes complete instruction manuals and application guides at no charge on selinc.com.

Quick Answer

SEL (Schweitzer Engineering Laboratories) is an employee-owned company founded in 1982 in Pullman, Washington, that manufactures protective relays, automation controllers, meters, and communication equipment for electric power systems. SEL relays are the most widely deployed protective relays in North American electric utilities.

Company Overview

Dr. Edmund O. Schweitzer III founded SEL to make electric power safer, more reliable, and more economical through advanced digital protection and automation. SEL remains employee-owned and headquartered in Pullman, WA, with manufacturing in the United States.

What SEL Makes

Protective relays (the core product line)
Automation controllers (RTAC series)
Power quality and revenue meters
GPS time servers (SEL-2407)
Industrial Ethernet switches (SEL-2740)
Communication processors

Where SEL Products Are Used

Transmission substations (line and bus protection)
Distribution feeders (overcurrent, recloser control)
Generator protection
Motor and transformer protection
Industrial power systems (refineries, data centers, pipelines)

Open Documentation

SEL publishes complete instruction manuals and application guides for all products at no charge on selinc.com — a distinguishing characteristic that makes self-study and independent commissioning accessible.

Frequently Asked Questions