Product SafetyProduct Lifecycle ManagementRapidly Sourcing Components InternationallyEnvironmental IssuesDesignIssuesJake MazurEric TarklesonJosh WongBen KershnerTeam 2 – Design IssuesNovember 19th, 2008The task of this team was to design a solar powered multi-seat computer system for deployment into rural schools. This included researching what technologies are currently available to provide the most efficient and cost effective method of runningmultiple computer terminals from a solar system. This task itself is a serious engineering challenge and it turns out that sourcing components for such a system in under-developed areas is also a big challenge.Certain considerations must be taken when designing anything that is going to be deployed to a foreign country, especially a developing one. When the rural element and placement inside of a classroom are added to the equation it only compounds the already existing issues. Product SafetySince we are designing a system that will be deployed in a school with no preexisting power, and around people without much experience with electrical equipment we need to take some extra precautions to make sure that the entire system is as safe as possible. There will be solar panels that will either be mounted on poles outside of the building or on the roof so we will have to make sure to protect these cables because they will carry high currents. The battery bank also needs extra safety measures because it will have the potential to unleash huge amounts of current should a short, or other low resistance connection (i.e. body) cross the terminals.The solar panels will be mounted outside. If we mount them on the roof then we need to make sure that the cable runs go into the structure through a watertight seal. Also there will need to be an earth ground installed in case lightning hits the building. The building itself must be structurally sound enough not only for the solarpanels but also for several people so that installation and maintenance is safe.If the building is orientated in such a way that the panels can not face the sun while they are on the roof then they will have to be mounted on a pole outside of the 2Team 2 – Design Issuesschool building. In this case extra precaution must be used to insure that a person is unable to access any wire leads because the current can easily kill a person. Also the cabling will have to be run underground so the wires will have to be enclosed in the proper type of duct to that they cannot be cut by someone digging in the area. They also must be completely weatherproof to avoid the wire insulation breaking down from the elements. One advantage to this setup is that the structure that the panels hang on can be used as an earth ground for the entire system.Once inside the building all wiring outside of the case should be in ductwork. This prevents a person from easily cutting the wires and also prevents animals from chewing through the insulation. The system case must have a hole that is not sharp so that the wires cannot fray over time. Also cabling should be secured to the case sothat it cannot easily be pulled out which could cause short circuits or broken hardware. Any short unintentional short circuits have a large probability of destroying the expensive equipment nearby or causing a fire.The battery bank must be carefully installed so as to minimize any possibility of short circuits. Each battery terminal should have a cover installed so that it is difficult to touch the electrodes accidently. All batteries should also be secured to thecasing so that they cannot move if the whole case is tipped or moved.There must be circuit breakers at several key points in the system to insure that if there is a problem the system will cut off power to itself and hopefully save the equipment from being ruined. There will be a circuit breaker between the solar panel array and the Charge Controller and also between the Battery Bank and the Inverter. These will trip if current exceeds expected ratings and will also allow the system to be manually shut down if the need arises.Following these simple precautions should allow the system to be safe from prying fingers, weather, animals and equipment failure. Also in the case of a failure troubleshooting should be easy because if our battery management system is running it will provide feedback about which components are not working. If a breaker is reset then it will also provide clues as to which part of the system failed.3Team 2 – Design IssuesProduct Lifecycle ManagementThe solar powered computer system is designed to be easily assembled, maintained, and recycled. The majority of the components used are commercial off the shelf components. This allows for easy replacement of damaged components andallows using other compatible components with minimal effort. It also allows for theefficient upgrading of obsolete components without requiring a redesign of the entire system.The system is comprised of four major independent systems, the server, the satellite dish, the solar array, and the battery array. Each of these major systems can be replaced by a compatible solution without the replacing or modifying any of the other components. There is one crucial component that is unique to our system, the power monitoring hardware. This hardware and software are custom built, but it interfaces with the server using a simple USB connection, and it is compatible with all UNIX-based operating systems.One of the greatest strengths of the design is the multi-terminal approach taken. Many hardware based multi-terminal approaches exist, but these add many more points of failure. The approach taken here is software based. This allows any server fitting a generic set of specifications to be used. Because of the constantly changing nature of computers, this is a powerful tool in reducing cost as no special hardware like thin clients are needed. Also software does not become obsolete as quickly as hardware and can be easily updated if needed.It is anticipated that the system will be completely sourced by Lenovo and then shipped as a single unit to the target deployment areas. Based on experiences dealing with foreign suppliers, it makes sense to have the units made in the US and then shipped to the developing countries. This allows for the highest quality components at the lowest possible cost. Because the primary components are already made, there is no need to take into account most of
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