Case Study Lightning

by Lee Howard, Lightning Eliminators and Consultants

The possibility of damage from a lightning strike is tremendous for any utility or power transmission firm.

The key is to prepare for and manage weather-related incidents.

Tri-State Generation and Transmission Association, a wholesale electric power supplier near Denver owned by 44 electric cooperatives, serves some 1.5 million customers.

The power supplier learned the importance of lightning strike preparation firsthand at its operations center in Westminster, Colo.

“For companies like ours—businesses that provide a critical service—it is important to avoid a service disruption or potential service disruption because of how it impacts customers’ lives,” said Jerry Coufal, Tri-State’s network operations supervisor.

Although companies might not face identical risks, lightning can be a top-tier concern for all.

“We had a strike to our Westminster facility that caused pretty severe damage in 1994,” Coufal said.

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Many people equate lightning strikes to fire damage, but the Westminster strike created havoc without igniting a single flame.

Instead, it damaged the company’s telecommunications equipment, and the damage was not confined to any one area.

Microwave radio antenna equipment, computers and associated phone systems were rendered useless in seconds, Coufal said.

“The severity of damage meant we had an extended-duration outage while we acquired new equipment to restore services,” he said. “It took us awhile to restore capacity, and it was the service disruption that caused the greatest grief. No utility wants to lose the use of its equipment and the ability to operate at full capacity.”

Tri-State realized it had to prevent similar occurrences at its telecom network operations center. The company sought several solutions and selected a Dissipation Array System (DAS) from Lightning Eliminators & Consultants (LEC) Inc. and LEC’s Spline Ball Ionizer terminals and Chem-Rod Grounding Electrodes.

LEC provides integrated, industrial lightning protection and prevention solutions, products and services using patented charge transfer technology, grounding systems engineering, surge protection, design and consulting based on physics and engineering.

To date, the company has installed more than 3,000 solutions in more than 69 countries and throughout the U.S. to companies in the petrochemical, oil and gas, biochemical, information technology, nuclear energy, utilities and manufacturing industries.

The company’s patented DAS technology has proven to be more than 99.7 percent effective in eliminating strikes to protected areas.

Contrary to the saying, lightning can strike the same place twice. Tri-State was unwilling to be unprepared twice.

“Like many places, lightning can be fairly intensive here in the Denver area, especially in the summer,” Coufal said.

In addition to striking vertically, lightning can travel horizontally and strike unexpectedly miles from a storm—the so-called “bolt from the blue,” Coufal said.

That unpredictability, combined with the risk Tri-State faced, made lightning protection important to Tri-State.

Soon after the 1994 lightning strike, Tri-State installed a hemisphere array LEC DAS at its Westminster headquarters and its main backup facility.

Unlike other lightning protection systems, the DAS is a “charge transfer” system, the only type of system where the lightning impulse is not encouraged, but discouraged.

The DAS completely isolates facilities from a direct lightning strike by bleeding off the induced charge on the protected area during a thunderstorm and reducing it to a much lower level in relationship to the surrounding environment.

Tri-State has had zero lightning strikes in its protected area since installing the system.

Discouraging lightning is a significant benefit to companies such as Tri-State, where a single strike to a mission-critical facility can cripple operations.

“The proof is in what we have experienced so far,” Coufal said. “We have not had any problems since the DAS installations, even though it is still very common to have bad thunderstorms in the area. When a storm is close by, we never experience any problems or loss of equipment due to that. The systems are working very well for us.”


Cutting Electric Fields in Half Means Zero Strikes at Tri-State

Reputable lightning protection providers perform thorough site engineering assessments before installations.

For example, after an evaluation, Lightning Eliminators & Consultants Inc. (LEC) engineers specify system components, placement and structural interfaces, and its designs account for environmental factors such as wind, ice and corrosion.

A team designs the lightning protection system to prevent two elements of lightning—upward streamers of positively charged electrons and step leaders of negative electrons that come down from clouds—from connecting to create a strike. The naturally occurring electric fields thunderstorms create give streamers the energy to rise upward in search of step leaders.

The success at Tri-State Generation and Transmission Association, a Colorado company in part of the country known for intense lightning, led LEC’s R&D department to return several years ago for an in-depth study of its DAS performance. The company placed an electric field monitor near the DAS array on the roof of the Tri-State facility and installed a second monitor 1,040 feet away and outside Tri-State’s lightning-protected zone.

After 99 days of analysis, LEC concluded that electric fields inside Tri-State’s DAS0-protected zone was, on average, 55 percent weaker than the surrounding area during thunderstorms.

Author

Lee Howard has more than 20 years of combined experience in the study and testing of electricity, electronics and electromagnetism with 16 years in the research, advancement and design of lightning and surge protection solutions. He is the program manager for engineering services at Lightning Eliminators and Consultants. He has a bachelor of science in electrical engineering and is a member of the Institute of Electrical and Electronics Engineers. He also has a certificate in power systems from The Georgia Institute of Technology.

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On 10 July 2015, a cloud-to-ground (CG) lightning flash that produced two ground terminations was photographed from inside the safety of a truck in southern New Mexico. An analysis of archived NLDN data verified that this was a two-stroke flash, and a close-up view of the first stroke shows that it also initiated at least 12 unconnected, upward leaders (or “streamers”) near the ground termination. No unconnected upward leaders were seen near the second ground attachment. After combining an analysis of the photograph with information provided by the NLDN, we infer that the first stroke was of negative (normal) polarity, had modest peak current, and struck about 460 m (± 24%) from the camera. Attachment occurred when an upward-propagating positive leader reached an inferred height of about 21 m above local ground. The second stroke struck ground about 740 m from the camera, and the height of its attachment leader is estimated to be 15 m. The estimated lengths of the unconnected upward leaders in the two-dimensional (2-D) plane of the first stroke range from 2 to 8 m, and all appear to be located within 15 m (2-D) of the main ground termination, with 24% uncertainty. Many of the unconnected upward leaders (inferred to be positive) exhibit multiple upward branches, and most of those branches have upward-directed forks or splits at their ends. This is the first report showing such extensive branching for positive upward leaders in natural lightning strikes to ground. None of the upward leaders can be seen to emanate from the tops of tall, isolated, or pointed objects on the ground, but they likely begin on small plants and rocks, or flat ground. In terms of lightning safety, this photo demonstrates that numerous upward leaders can be produced near a lightning strike point and have the potential to damage or cause injury at more than one specific point on the ground.

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