Across industries, the power of lightning strikes to injure personnel, destroy assets, and disrupt processes through fire, explosion, or electrical damage is clear. FedEx Express takes lightning seriously. While FedEx was expanding its leadership in overnight package delivery in the early 1980s, Larry Marsh and a team of co-workers were intent on safeguarding company personnel, assets, and productivity from lightning strikes. By company directive, Marsh''s goal as a project manager assigned to the company''s Memphis Superhub was to ensure delivery commitments despite the area''s frequent lightning storms. Packages had to be sorted and processed each day within a two-hour window for all deliveries to be made on time, or delivery was free, based on the company''s customer-focused performance guarantee.
With a billion-plus square feet of connected buildings and ramps, the Superhub was a critical linkage point in FedEx Express''s expedited delivery service. Thousands of employees kept this complex operating smoothly and many, such as those out on the exposed tarmac, drove tugs or container vehicles for loading or unloading aircraft.
"Lightning strikes can be devastating in a range of different ways, but our priorities were clear," said Marsh. "First, protect our personnel, especially those out in the open, since it was hard to clear the ramps and runways before storms arrived. Next, protect our planes, buildings, equipment, and assets. Damage to anything had down-the-line effects, like a row of dominoes. Everything from unloading and sorting onward had to work on time, every time for us to meet our delivery commitments. The ever-expanding number of aircraft also required us to put in above-ground fuel tanks, which we wanted to protect from lightning strikes as well."
One technology, the Dissipation Array System (DAS), has proven to be the preventative solution for lightning protection -- topping 30,000 system years with 99.7% reliability, and cutting storm-induced voltages by up to 7,000% in protected zones, thus reducing lightning risk. DAS, a proprietary application of Charge Transfer Technology, originated as a lightning prevention system that the former chief engineer for NASA''s Apollo moon landing mission and space shuttle design team developed to protect high-risk mission facilities.
Because it prevents rather than redirects lightning, DAS is possibly the best long-term solution to lightning strike problems. One company, Lightning Eliminators and Consultants, Inc. (LEC), based in Boulder, CO, has long been at the forefront of DAS development. In the three decades since LEC introduced DAS into the US marketplace, it has been the only lightning protection system proven to prevent lightning strikes to any protected facility.
When FedEx turned to LEC for a solution, LEC custom-engineered DAS for the Memphis hub, working closely with Marsh and his team, who oversaw installation at the site. For example, some of the aircraft needing protection were close to active airport runways, which had structural height restrictions. LEC worked with the team to stay within the restrictions, meet FAA runway profiles, and still protect aircraft and ground equipment from the effects of lightning. (Photo, taken at sunset, shows FedEx''s Paragon Array installation.)
"At first we had our doubts about DAS, but the system works," says Marsh. "We thought if we could eliminate half the strikes, it''d be useful. Eighteen years later, to my knowledge, there hasn''t been one strike. The only exception to this was when we took a DAS system off a building to re-roof. That''s when lightning struck, but it didn''t penetrate any of the protected areas.
"As far as I''m concerned, LEC technology is standard equipment when we put in a new facility where there''s a high incidence of lightning strikes," says Marsh. "We''re protecting the life and safety of our personnel, we''re protecting our assets, and we''re preventing service disruption for our customers."
The Problem with Lightning Rod Concepts
"Lightning strikes cause more deaths, injuries, and damage than all other environmental elements combined, including hurricanes, tornadoes, and floods," according to the US EPA Alert Lightning Hazard to Facilities Handling Flammable Substances, published in May 1997. "Lightning accounts for 61% of the accidents initiated by natural events," confirms a 1995 Journal of Hazardous Materials report.
Even if the facility is not directly struck by lightning, secondary effects such as bound charge and electromagnetic pulses can fry sensitive circuitry in the vicinity. Failures may be catastrophic or a momentary or long-term lockup, requiring replacement, repair, reprogramming, or rebooting. For US corporations, preventing lightning strike damage would not only safeguard critical processes and save millions of dollars of equipment and facility damage each year, but also protect the health and productivity of personnel.
The danger of a lightning strike is exacerbated by so-called "prevention" devices such as lightning rods and early streamer emitters, which are designed to collect and channel the force of a strike to ground. This 200-year-old concept was never intended to protect modern high-tech automated facilities, but rather barns and other wood structures of that era.
"The Franklin rod system is 200 years old and wasn''t built for today," said Don Zipse, a seasoned electrical engineer specializing in electrical accidents, who was awarded the IEEE Standards Medallion for his work promoting electrical standards. "Its main drawback is that it actually attracts thousands of amps to flow next to your equipment. Do you really want lightning striking next to you unless you''re 100% sure you can control it?"
Doubts of Franklin rod and ESE effectiveness in high-risk field conditions were raised by the National Fire Protection Association (NFPA) Bryan Report, an independent evaluation panel on ESE lightning protection technology conducted by its Standards Council in September 1999. Among the conclusions reached: "Neither the ESE air terminals nor the conventional Franklin rod appear to be scientifically or technically sound when evaluated in field tests under natural lightning conditions."
The Solution: DAS Technology
Given the random and destructive nature of lightning strikes, how can businesses protect their personnel, facilities, equipment, and processes -- including those of a sensitive electronic nature such as data centers and control systems? The answer lies not in channeling lightning, but in preventing the charge from accumulating in the first place.
Let''s start with the source. As a storm intensifies, charge separation continues within the cloud until the air between the cloud and earth can no longer act as an insulator and a strike occurs. The lightning strike "neutralizes" any charge difference between the cloud and ground, a process similar to shorting out the terminals of a battery. When structures sit between the earth and the clouds, they are likewise charged. Since they short out a portion of the separating air space, they can trigger a strike.
The lightning strike hazard for a given facility depends on a number of factors, including the facility''s location, size, and shape. The characteristics of a structure -- its height, shape, size, and orientation -- influence the hazard. Taller structures tend to collect strikes from storm clouds in adjacent areas and trigger additional strikes as well. The larger the structure size, the greater the hazard of lightning exposure.
DAS is based on a natural phenomenon known to scientists for centuries as the "point discharge" principle, where a sharp point in a strong electrostatic field will leak off electrons by ionizing adjacent air molecules, providing the point''s potential is raised 10,000 volts above that of its surroundings. DAS provides thousands of points with specific point separation that simultaneously produce ions over a large area, thus preventing the formation of a streamer, the precursor of a lightning strike. The system prevents strikes by continually lowering the voltage differential between the ground and the charged cloud to well below lightning potential, even in the midst of a worst-case storm. (Photo shows two installations: one on a communications tower and one on a process industry tower.)
"With a charge transfer system like DAS, you''re neutralizing the leader, so the earth charge doesn''t flow back to the cloud above," says Zipse, who currently chairs the IEEE''s Project 1576, a workgroup dedicated to developing a standard for lightning protection systems at industrial and commercial installations. "That prevents lightning strikes and most of their secondary effects. DAS has improved on the naturally occurring charge transfer phenomenon, and engineered it to specific sites. The charge transfer system of preventing lightning strikes to protected areas is a valid concept and will replace the Franklin rod in many applications."
DAS Success Stories
Mid-Carolina Electric Cooperative: FedEx Express is not the only example of a successful DAS implementation. Lee Ayers, system engineer for the Mid-Carolina Electric Cooperative, a distribution utility in Lexington, SC, turned to DAS after suffering severe lightning-related damage. "If a single substation was hit, we could lose as many as 4-5,000 customers in the initial outage," said Ayers, whose facility serves about 42,000 customers in the Columbia, SC area. "Total replacement cost for damaged equipment was over a million dollars during a 5-year period -- the transformers cost about a quarter million each. Our insurance carrier was constantly raising our rates and pushing us to do something to cut their losses."
The benefits of deploying LEC''s DAS equipment were significant, according to Ayers. "Over a comparable 5-year period, our losses to collateral lightning damage on the protected facilities probably amount to no more than $50,000." Mid-Carolina has since made DAS standard on all new installations, and Ayers has recommended the system to other utilities facing electrical storm damage.
Computer Power/ALLTEL: Fred Parvey also knew that lightning-related damage had to stop. As the new manager of Computer Power Inc.''s central Data Center in Jacksonville, FL, an area notorious for lightning strikes with approximately 100 lightning days per year, he was responsible for ensuring the processing of mortgage data for banks and lenders nationwide. The year before, in 1985, Computer Power had processed more than 5 million mortgage loans.
That same year, Computer Power experienced a day-long system outage due to lightning striking the company power station, housing two diesel generators, an uninterruptible power supply (UPS) backup system, and switch gear. Up to 10,000 end users on PCs and terminals were idled, unable to process loan information, until the system was restored. The strike destroyed the power station, UPS, and switch system at a cost of $150,000. Another $100,000 of computer equipment and communication controllers had to be replaced as well, where keyboards had melted and power supplies failed. It was weeks before a new UPS backup system was in place.
"We were totally knocked down and instantly off-line," said Parvey. "That''s unacceptable when our clients rely on us for continuous service to keep their businesses going. When our clients turn on their PCs and terminals, they expect their systems to work, just as we expect the lights to go on when we flick the light switch."
When ALLTEL, a provider of worldwide loan service automation and technology consulting, as well as comprehensive communications services, bought the 9-acre Jacksonville campus in the 1990s and promoted Parvey to director of advanced technology solutions, he turned to DAS technology to avoid lightning-related damage.
LEC installed DAS technology on all buildings and upgraded grounding from existing copper-coated rods, which permitted dangerous electrical surges in nearby lightning strikes, to low impedance Chem Rods. In addition, it placed Spline Ball Ionizers (SBIs) on air conditioning vents and rooftop equipment where appropriate. SBIs are hybrid devices that prevent lightning strikes with point discharge ionization, as well as collecting and redirecting any lightning strikes that may get through. (Photo shows a technician installing DAS in a plant setting.)
LEC also replaced a number of existing lightning rods in some locations with Spline Ball Terminals (SBTs). These smaller versions of SBIs simply screw into existing lightning rod sockets. Finally, they added state-of-the-art surge suppressers to circuits, electrical panels, and service entrances. LEC''s industrial grade surge protection devices are available with up to 1.2 million amps per phase of surge protection, the world''s highest rating.
To date, ALLTEL''s Jacksonville campus has suffered no lightning strikes since implementing DAS technology, and system downtime is now insignificant.
"Lightning is no longer an issue for us," says Parvey. "We now process more than 20 million mortgage loans valued at $2 trillion annually, so we have to be at the top of our game more than ever. When clients depend on us for continuous data processing via 70,000 PCs and terminals connecting to our system, I know we can deliver."
Mountain Village Metro District Gondola: While DAS excels at fixed applications, at least one corporate entity is looking to DAS to improve its public transportation service record, while protecting personnel, the public, its assets, and equipment from lightning strike. The Mountain Village Metro District Gondola system in Telluride, CO, already the first public mass transit gondola system of its kind in the nation, may soon become the first gondola-type system to operate year-round through lightning storms, opening the door to expanded tourist trade during the lightning prone summer months in scenic, mountainous areas -- thanks to DAS technology.
The development, which deploys DAS to prevent damaging lightning strikes, is of critical interest to ski, tram, and gondola lift operators worldwide, as well as to the engineers and managers of other mass transit systems, such as electric rail and bullet-train type systems, who face similar operational issues.
In consultation with gondola engineers, LEC custom engineered, designed, and installed three interconnected systems for low impedance grounding, high-energy surge protection, and lightning strike prevention. The resulting plan was implemented in three phases, over 2 ½ years, to protect all towers, gondolas, terminals, control centers, and surrounding buildings.
DAS installation took place during normal maintenance shutdown periods and was completed in October 2001. DAS lightning strike protection now extends from above the gondola towers to the ground. Gondola passengers ride in the equivalent of a "lightning protected tunnel." In combination, the custom built and installed DAS systems prevent lightning strikes; the Chem Rods quickly send any incoming power surges harmlessly to ground; while Sandwich Block surge suppressers provide an extra assurance that the entire gondola system will work with utmost reliability.
"When we test the entire system this lightning prone summer, I expect we won''t have any stops or lightning-related problems," said Candace Kjome, director of the Mountain Village Metro District Gondola. "I expect we''ll have zero closure time as a result of installing the LEC equipment. The service improvement will be dramatic."
If the experience of Henry Goehle, formerly in charge of managing the Devil''s Head Lookout Tower -- between Pike''s Peak and Denver, the most active US lightning zone outside of southeast Florida -- offers any clue, DAS''s contribution to protecting US personnel, facilities, equipment, and processes in a whole range of industries will be bright indeed.
"When the DAS system went in, I actually saw lightning striking as it approached the tower, then no strikes, followed by more lightning on the other side of the mountain after the storm had passed," says Goehle. "Because the lightning quit striking in our protected area, I knew it was working."