Installing DAS system at Auburndale cogeneration plant. Click here to enlarge image
PRIOR TO THE INSTALLATION of a new lightning protection system, the Auburndale Power Partners 150 MW cogeneration plant, located east of Tampa, Florida, usually sustained up to six lightning-related outages each year. Invariably, a lightning strike caused damage to the plant’s sensitive control equipment. According to Glenn Weigle, plant engineer, each lightning strike can cost the plant up to $25,000 from lost revenue and the costs for repairs.
Although the 160-foot high exhaust stack of the plant had an existing lightning protection system, it did not protect the plant from all strikes. An inspection of the existing protection system revealed that it had very serious grounding problems. The plant also found that the company which supplied the original protection system was no longer in business.
After evaluating the different options, and speaking to other plants having similar problems, Auburndale decided to install a Dissipation Array System (DAS). The system was supplied by Lightning Eliminators & Consultants (LEC).
Weigle states that the DAS technology is based upon a natural phenomenon called the “point discharge principal.” According to this principle, in a strong electronic field, a sharp point leaks off electrons by ionizing adjacent air molecules, providing the point’s potential is raised 10,000 volts above that of its surroundings.
When in operation the DAS system creates thousands of simultaneous ion producing points. These points prevent streamer formation, a precursor to lightning strikes. Since the ionization process creates current flow from the points to the surrounding air, the DAS system is able to remove the storm-induced charge from being transferred to the air molecules. By lowering the voltage difference between the ground and the charged cloud, it is possible to prevent serious lightning strikes. Weigle states that unlike lightning rods, which are meant to get hit by lightning, the DAS system is designed to prevent lightning strikes.
Besides installing a DAS system on the stack, the plant has also installed six LEC supplied Spline Ball Ionizers (SBIs) on the 90-foot boiler. The SIBs are hybrid devices that prevent lightning strikes with point discharge ionization. In addition, the plant has replaced approximately 50 existing lighting rods with Spline Ball Terminals. These are smaller versions of the SBIs.
After implementing the DAS technology, the plant only experienced one outage from lightning strikes in 2000, and this only occurred during the year’s worst storm. Reducing lightning strikes has saved the plant approximately $100,000, says Weigle, and the cost savings experienced in the first year of operation have paid for the systems. Currently the plant is planning the installation of further DAS systems on five buildings and a cooling tower.