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Welcome to Axiom's INSIDE Engineering Newsletter. ISSUE 1: Axiom
Engineering Launches Site
http://www.axiomca.com January 1, 1998 marked the launch of Axiom’s Web Site and another way in which to expand our client support services. This website takes more than a simple internet ‘business-card’ approach to web presence. We’re creating an on-line resource centre that you can use as reference for your projects and your business. If you’ve ever been stuck without being able to get basic engineering information for your project, you’ll appreciate what we’re doing. We’ve also incorporated a way of making it simpler and faster for you to obtain a Fee Proposal for your projects. The Fee-Request Form saves you time by allowing you to give us the exact information we need, in a pre-formatted web form, that you submit to us right from the webpage. There is room to add your comments and description of what the project involves, as well as your deadline for the Fee Proposal. If you have site and floorplan sketches, you can fax them to us at (905) 566-5203. With the Fee Request Form, you don’t have to pick up the phone and waste time repeating yourself. Once we receive your form, we generate a Fee Proposal and send it to your office immediately. No more telephone tag. Another active feature is the Electrical Technical Glossary - giving you access to the most commonly used lighting, power, telecommunications, and life safety terminology. The Unrelated Links is a dynamic section keeping you informed of the newest and most interesting web sites covering a variety of topics such as Entertainment, Computers, Cars, Education, Travel, and more. The website’s future will be much more dynamic. We’ll have an Electrical and Mechanical Technical Reference Library where you’ll find articles giving design tips and information on many topics, like the Lightning Protection Systems article in this issue of INSIDE engineering. There will also be specialty sections aimed at addressing the specific interests and needs of architects, developers, and other engineers too. On the technical side, we’re making the transfer of drawing and specification files faster and more reliable for you by developing a FTP (File Transfer Protocol) directory. With this tool, we can transfer files back and forth with you through a password-protected directory. FTP is better than modem transfer because you don’t have someone sitting in front of a computer waiting to send or receive a file - you’ll be able to pick up or deliver files at your convenience. The FTP is also better than email because you’ll be able to pick up the files immediately - that means no more waiting for hours (or days) for an important file. We hope you find our website informative and useful, in your day to day business. Since ancient times, lightning strikes have mystified and even terrorized the human race. And so they should have. Lightning remains one of the most powerful forces on Earth. The latest theory on how lightning is generated is known as the charge-reversal temperature theory. A ‘thunder cloud’ is identical to a normal cloud formation, except that the air velocities involved are much higher. However, to be capable of generating lightning, the cloud must be at least 3-4 km deep. The taller the cloud, the more frequent the lightning. It’s known from waterfall studies that fine precipitation (such as snow), acquires a positive electric charge, whereas larger particles acquire a negative charge. The centre column of thunder clouds can have updrafts exceeding 120km/hr, that separate the charges by carrying the finer (positive) charges to high altitudes. The heavier (negative) charges remain closer to the cloud’s base. In fine weather conditions, the Earth normally carries a negative charge, with the corresponding positive charge in the upper atmosphere to maintain an electrical balance. This charged state results in a downward electric field of about 100volts/metre of surface area. However, directly below a thunder cloud, the field often exceeds 20,000volts/metre and leads to point discharges that occur in a few ways: cloud-to-cloud, cloud-to-air, cloud-to-ground, and ground-to-cloud. Only about 15% of lightning activity involve cloud-to-ground discharges, although empirical evidence shows that the frequency of lightning strikes is increasing on a global scale. The development of such a discharge is a two-staged sequence, with one process being initiated from the cloud while the second is initiated from the ground or earth-bound structures. Both processes rely on the ionization, or complete breakdown, of the air that occurs when the electric field between cloud and ground is sufficiently-high. This increased understanding of the mechanics of lightning strikes is responsible for the aggressive stance owners are taking in protecting people, buildings, and equipment from its often-disastrous effects. The fundamental concept behind every lightning protection system (LPS) is to provide a path of low resistance so a discharge can enter or leave the Earth without causing significant damage or loss of life. The parts of buildings most likely to be struck are those that project highest above a roofline, including the roof edge, and the power distribution systems. A typical LPS consists of three basic elements: 1. A system of air terminals and intercepting conductors on the roof and roof edges to collect the discharge (like eavestroughing). 2. A system of down conductors to lead the collected discharge safely down to Earth (like rainwater leaders). 3. A system of grounding electrodes that dissipate the discharge away from the protected building (like a leeching field). Secondary effects known as sideflash and spark-over allow a discharge(s) to jump from one conductive surface to another, causing collateral damage. To overcome this further hazard, an additional system of interconnecting conductors is used to connect other conductive bodies on the roof (HVAC units, ducts, fans, pipes) to the main intercepting conductors. In addition to protecting the structure, surge-arrestors are installed within the main electrical distribution equipment to protect against over-voltages. We protect individual panels with transient voltage surge suppressors (TVSS) that greatly reduce the surge that the equipment is subjected to. The same type of TVSS is used to protect the data and telecommunications system.A surge or spike in these systems can lead to tens of thousands of dollars in damage to electronic equipment and must not be ignored when designing a general protection system, even if lightning protection is not involved. It is also possible to use the building structural members as part of the interception and downleading of the lightning discharge. The structural steel must have adequate cross-sectional area and must be made electrically-continuous. Several factors are considered in the determination of lightning risk. One factor is the structure’s intended use: a single family dwelling is less critical than an office or hospital. Another factor is the type of construction: a wood building is more at risk than an electrically-continuous steel structure. The relative location of the structure is also important: if the building is located near taller buildings, the risk is less than if it’s the tallest one. Similarly, a building on flat land is at lower risk than one on a hillside. Finally, the frequency of lightning for a particular region, is crucial in determining the overall risk. This information is obtained from Isoceraunic Level Maps that indicate the number of thunder-storm days a region gets per year. The average for southern Ontario is about 30-35 thunder-storm days per year. By contrast, Florida gets an average of 90-100 thunder-storm days. A typical 2-3 storey structure, with a floor-plate area of 3,500m2 (37,600ft2) requires about 20 ground rods - each with an installed cost of about $450-$600, resulting in a $12,000 system, assuming that the structural steel is utilized in the installation. Is protecting a few thousand dollars of computer equipment, the building, and its occupants worth $12,000 for a Lightning Protection System? Yes. You know it’s coming. You’ve heard all about how the computer crisis in the year 2000 is going to prevent your alarm clock from going off, your coffee-maker from working, and your car from starting. And it’s only going to get worse as the year 2000 gets closer. We’re taking a more optimistic attitude about the whole thing - we’re not going to dwell on something we can’t control. But it is important for you to have some background information on the problem so you may be able to find a way of avoiding, or at least, working around the so-called crisis in 2000. First, let’s understand how this all started. Back in the late 1960s, computer memory was very valuable, so when a way of conserving some of it by representing years as two-digit numbers was conceived, there was no question that it would become an international standard. And it did. In this system, the year 1966 is represented as ‘66’. The problem is that the programs and Read Only Memory (ROM) computer chips based on this standard won’t know what to do when the year is larger than 1999 because all they will see is ‘00’. So what’s the big deal with ‘00’? Computers do everything based on mathematical calculations and algorithms. Throw in ‘00’ and a simple multiplication turns important things into a zero. What’s even worse is that in computerland, a division by zero is fatal - everything just hangs. Imagine if that happens to even the simplest electronic devices like clocks, telephones, radios, car electronics, and aviation equipment! OK. But we don’t all run the Information Systems for IBM or Air Canada. How is this problem going to manifest itself with people in the design and construction industry? The most important applications to be affected by the year 2000 problem will be your application software for accounting, personnel and security records, loan and insurance calculations, and business forecasting. It’s not hard to see why problems with interpreting dates will cause problems with accounts receivable and payable. There are basically two aspects to the year 2000 problem - all the other problems you hear about are just child-processes of these: 1. The year 2000 starts with a ‘2’. Even programs that are set up to read four-digit years may only accept those that start with a ‘1’. Smart huh? 2. The year 2000 is also a leap year so it has 366 days, not 365. Every date in the year 2000 will be wrong on affected systems. This problem will affect PC’s and Windows-based systems as well - not just mainframes. Microsoft states that its 32-bit applications (like WIN95 and NT) are capable of handling the years 1980 to 2099. However, most of its 16-bit Windows (WIN 3.x) applications will be affected. These systems will think that the year 2000 is actually 1980 or 1984. A patch file is available by downloading a file called YEAR2000.ZIP from http://www.winmag.com/people/melgan/year2000 - just follow the instructions in the README file. Another information-packed site is http://www.year2000.com which has step-by-step approaches for solving year 2000 problems. In terms of your hardware, the problem is centred in the RTC (Real Time Clock) which holds the time and date when the computer is turned off. The RTC information is stored as dd/mm/yy - each as a 2-digit number. When the RTC/BIOS date is requested, some BIOS will add ‘19’ as the century while others apply a value stored elsewhere in the CMOS. The problem is with the BIOS that adds ‘19’ since this value would be passed along to any program that requests it. Some vendors have already updated their BIOS to check the century code on boot-up, many have not. Do not do any testing during normal business hours - especially at lunch time if you’ve got three or four jobs going to tender by the end of the day. You may want to make a complete backup of your hard-drive before you start doing any testing. To test your PC, set the date and time in the Windows Control Panel to 12/31/1999 at 11:59pm and turn off your computer. Leave it off for about two minutes, turn it back on and check the date and time. If it reads 12:01am on January 1, 2000 you’re fine. If things don’t work, you can recover, by pressing the RESET button on your computer. Press the DEL key when the ‘To Change System Settings Press [del]’ message appears. You’ll then see a menu that will let you change the date and time. If you had a crash, download the fix file and try it again. Next, you may want to try opening some software applications that you know are date-driven. For your information, most of Microsoft’s Office applications are good till at least 2019, but programs like Lotus 1-2-3 and Quattro-Pro will have a problem working. Use the software to calculate and sort using the dates: January 1, 2000 and February 29, 2000. The good news is that most of us upgrade our software and hardware every three to five years. It may be wise to upgrade in early 1999 and make sure that all the new equipment is year 2000 compliant.
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