The Electric Power Board (EPB) of Chattanooga, Tenn., was motivated to improve reliability across its 600-square-mile service area. As part of the city's effort to improve the infrastructure for achieving greater societal benefits, including attracting businesses, EPB recognized that, in a truly smart city, an electric grid would boast less downtime for businesses and consumers. Further, the reduced duration of power outages would translate into financial savings for local businesses and greater economic competitiveness. EPB set out to install distribution automation with matched funds from U.S. Department of Energy (DOE) stimulus monies, which would accelerate deployment.

Knowing that they wanted to build an intelligent and self-healing grid, EPB was impressed by S&C's IntelliRupter® PulseCloser Fault Interrupter.

S&C Solution

EPB's final phase-one deployment included a fully automated distribution network with more than 1,100 IntelliRupters. That is one IntelliRupter device for every 0.6 circuit miles. EPB's planning strategy for this deployment involved evaluating the number of customers per segment, load per segment and the amount of exposure per segment.

Valued Outcome

Estimates based on industry studies indicate that, prior to the automatic restoration system's implementation, Chattanooga's economy was losing $100 million each year due to power outages. EPB believed that a restoration system such as S&C's IntelliTeam should be able to eliminate about 40 percent of the interruption minutes, ensuring that the societal impact would be relatively short.

With S&C's field-proven self-healing solutions in place, Chattanooga now experiences dramatic decreases in the duration of power outages. EPB has said that it has exceeded the projected 40 percent improvement in reliability. "We're frequently in excess of 60-to-65 percent improvement in every metric that exists," said David Wade, EPB executive vice president and chief operating officer. Now, when EPB experiences events, within seconds its new automation system restores power to all those who can have their power restored. "Even if a person's outage cannot be automatically restored because they are in the damaged section, automating the system improves reliability for everyone because it allows our crews to go right to the problem and get to work sooner," says Wade.

Ensuring power reliability in all weather conditions is a priority for EPB.

With its new distribution automation system switching on a fiber network, EPB says during a single storm event, 42,000 homes had their electricity restored in two seconds. This is a dramatic improvement over its previous average restoration time of nearly 17 hours.