| Jenis | Manufacturer |
|---|---|
| LamanWeb | https://www.selinc.com/ |
| Nombor telefon | +1.509.332.1890 |
| Alamat | 2350 NE Hopkins Court - Pullman, WA 99163 USA |
   |
In 1982, Edmund O. Schweitzer, III, invented the first microprocessor-based digital protective relay. The SEL-21 was the culmination of research done for Schweitzer's doctoral thesis, and it ushered in a new era of power system protection and went on to revolutionize the electric power industry.
