With the proliferation of electronics and electronic-controlled systems in our everyday lives, as well as our dependence on electronics to run businesses, we have learned how vulnerable the integrated circuit is to high-voltage transients superimposed on electrical circuits.
A study at the Palo Alto, CA-based Electrical Power Research Institute (EPRI) think tank found that 60 percent of all power directed to commercial buildings is consumed by electronics and electronic-controlled systems. This figure is projected to increase to 80 percent in the next decade, and it is loads of this type that are susceptible to the effects of transient surge voltages. The electrical designs of most new buildings make electronics an integral part of all building power distribution systems, and surge protective devices (SPD) are becoming a standard for buildings' electrical design.
A downside to the replacement of electro-mechanical relay-based signal systems and tube-type electronics with solid-state systems is that while the new systems are a lot smarter and more flexible, they are immensely more vulnerable to voltage transients. In spite of the risks, builders may challenge electrical designers to justify the use of SPDs in commercial designs. Building owners want "smoking gun" evidence of the effects of electrical surges. They want to see a direct cause and effect. Though many catastrophic events abound allegorically, cost-cutting entrepreneurs want hard data.
A power surge risk analysis to determine if there is a need for surge protective devices is advisable for any facilities professional concerned with the issues of power influx. Results of a power surge risk analysis are dependent upon a variety of parameters. These parameters can be broken into four areas and are assessed by the user.
* The first area is the frequency and location of incidents caused by environmental effects--natural or man-made. Lightning and the number of incidences in a given area are a primary source of power surges. Data can be gathered from the weather service in the form of isokernumic charts indicating the number of lightning strikes per square kilometer, per year. Manmade incidents are a combined result of power switching and nearness of the site to utility switchyards. This will affect the number and severity of the switching event.
Also to be considered is the geographical location of the facility. A mountaintop site is more susceptible to lightning strikes than similar facilities in low-lying valleys. Sites with tall communication towers run a higher risk of lightning-induced surges coupling with a building's electrical conductors.
* The next consideration is the susceptibility of electrical and electronic equipment to various impulse-withstand levels. The lower the level, the higher the risk. For the most part it may be assumed that equipment manufacturers have not built in protection for their equipment. The Computer and Business Equipment Manufacturers Association (CBEMA), Washington, D.C., (now known as the Information Technology Industries Council [ITI] [www.itic.org]) has long published a susceptibility chart for various types of electronic equipment.
* Another factor to consider is the economic impact from the disruption of business operations. For businesses such as public utilities, a shutdown is near disastrous.
* Finally, consider the possibility of loss of life from electrical shock or fire.
Facilities professionals should weigh these four areas of power surge risk analysis. All four factors and the predictable expense should be measured against the cost of SPDs. If the anticipated expenses exceed the expense of the SPD, it is then shown in bottom-line terms to be a justifiable expense.
David J. Strawn, technical sales specialist for Richmond, VA-based United Power Corp., is an electrical engineer with 25 years of experience in the power quality industry.
The End Justifies the Means
More often than not the expense of surge protective devices is an afterthought to a natural or manmade environmental event. Securing buildings from disasters associated with power surges may require bottom-line terms based on real-life consequences, as follows:
* Protection is installed only after a catastrophic event to prevent future occurrences.
* Protection is budgeted based on cost of payback analysis. This can be difficult to collect.
* Surge protection is installed as a safeguard in the event of occurrences based on subjective data such as weather patterns and utility switching. This is the insurance approach.
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|Title Annotation:||growing need for electrical surge protection|
|Author:||Strawn, David J.|
|Article Type:||Brief Article|
|Date:||Aug 1, 2000|
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