Case Study: Tohono O'odham Utility Authority achieves faster fault protection and outage reduction with Schweitzer Engineering Laboratories' SEL-T400L

Tohono O'odham Utility Authority - Customer Case Study

The Tohono O'odham Utility Authority (TOUA), a small tribal utility in Arizona, faced significant challenges providing reliable electricity across its vast, remote desert territory. Severe monsoon storms and microbursts frequently caused damaging faults on their system, leading to customer outages and requiring their small crew to spend long hours locating problems and restoring power. To modernize aging equipment, they turned to Schweitzer Engineering Laboratories (SEL) and installed the SEL-T400L relay.

The SEL solution implemented the SEL-T400L relay with advanced time-domain technology. This provided unprecedented tripping speed to quickly clear faults and incorporated traveling-wave fault locating to pinpoint issues. Shortly after installation, the relay was successfully tested during a major windstorm, clearing seven faults in under 2 milliseconds each without causing an outage. For TOUA, this meant no disruptive blackouts for their customers and no dangerous, lengthy restoration trips for their crew, significantly improving reliability and operational efficiency.

Tohono O'odham Utility Authority

Darrold Hobbs

Operations Manager