Computers, process control equipment and other computer-related products such as ethernet
extenders are susceptible to damage from high-voltage surges and spikes. These are most often caused by lightning strikes. But there the surges and spikes can also result from other causes, including direct contact with power/lightning circuits, static buildup on cables and components, high energy transients coupled into equipment from cables in close proximity, potential differences between grounds to which different equipment’s are connected, poorly wired systems and even users who have accumulated large static electricity charge build-ups on their clothing. Electrostatic discharges from a person can actually produce peak voltages up to 15 kV with currents of tens of amperes in under 10 microseconds.
A manufacturing environment is especially susceptible to such surges due to the presence of motors and other high voltage equipment. The main thing to keep in mind is that the effects of surges due to these other sources are no different than those due to lightning. Protection from one will also protect from the rest.
The use of surge and lightning protection power strips is always recommended. Some common brands are Belkin, APC (News
), Black Box and Tripplite. A lightning rod or air terminal with grounding is also recommended for areas prone to powerful lightning strikes.
Lightning rods and air terminals have traditionally been the primary defense against lightning. The basic concept is the provision of a preferential terminal for lightning that might have otherwise hit a vulnerable part of the structure. An air terminal can only protect a portion of a building, so most structures will have several lightning terminals. The spacing and positioning of them has been well understood for many years and the proper configuration and installation is detailed in well-known standards, such as NFPA 780 (National Fire Protection Association). Direct-effects protection also includes a system of down conductors connecting the air terminals to the grounding system.
The configuration of the grounding system is important, and depends on things like soil conditions, building construction and the presence of other underground conductors. Grounding systems can be created with driven ground rods, plates and also with a counterpoise, or a buried cable encircling the site. A counterpoise adds greatly to the protection from earth voltage rises that may injure people standing on the ground.
Keep in mind that nothing is 100% fool proof and the best, and cheapest, way to protect your computer, or electronic gear like Ethernet extenders, is to unplug all power, telephone, cable and antenna connections during a lightning and thunderstorm.
Brian Solomon is a Web Editor for TMCnet, covering news in the IP communications, call center and customer relationship management industries. To see more of his articles, please visit Brian Solomon’s columnist page.
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