SEL Protective Relay Withstands EF5 Tornado

Challenge

Substation equipment must withstand extreme weather conditions, but no one expected that an SEL protective relay would remain standing and operational when an EF5 tornado destroyed an entire utility substation.

In the late afternoon of May 22, 2011, a catastrophic, EF5 multiple-vortex tornado struck the city of Joplin, Missouri. The tornado completely destroyed an Empire District Electric Company brick substation and left 20,000 customers without power.

When Empire’s crew began to assess the demolished substation, they discovered an SEL-501 Dual Universal Overcurrent Relay that was part of a free-standing 12 kV breaker. Amazingly, the SEL relay appeared undamaged—it had survived an EF5 tornado!

Solution

Within ten days of the tornado, power was restored to approximately 12,000 customers (the remaining 8,000 customers were unable to receive power because their homes were damaged or destroyed). The SEL-501 was placed into Empire’s spares inventory for future use.

With the assistance of its suppliers and contractors, Empire completely rebuilt the substation in just seven months. During that time, SEL expedited the delivery of new SEL relays to Empire’s panel manufacturers. Based on SEL’s natural disaster policy, they supplied equipment and services to Empire at a considerable discount.

Results

As a result of their restoration efforts, Empire was honored with the Edison Electric Institute’s Emergency Recovery Award, which recognizes efforts made by electric utilities to restore service breached by severe weather conditions or other natural events.

Years later, the SEL-501 Relay was discovered in the spares inventory, retested, and found to be in working order. Empire returned the relay to SEL for cleanup and retesting. SEL provided Empire with a brand new relay and kept the SEL-501 Relay as a reminder of the company’s legacy of product durability and reliability.

Customer Profile

Customer: Empire District Electric Company

Location: Joplin, Missouri

Industry: Utilities

Application: Feeder Protection