Please can someon help?!:-
Power supply for computers Armitage Senior Secondary School, Janjang-Bureh,
Janjang-Bureh Island, Central River Division, The Gambia, West Africa.
I used to teach at North Bromsgrove High School, in Bromsgrove until retirement. I started a link between North Bromsgrove High School and Armitage School in 1987 and it has been going strong since then. We invite a boy, a girl, and an adult here for three weeks each July and some of us visit Armitage for two weeks each year - next outward visit Feb 2004
[We are raising funds for a library for the school and its associated middle school. We need about £5000 to complete it, add furniture and supply books. (If you come across any means of raising that money do please let me know!)]
We supplied the school with computers, but these are of little use at the moment because the power supply to the school is overloaded and the voltage appears to be around 150V much of the time. The school is on Janjang-Bureh Island and the electricity supply (nominally 240V) comes from a generator which is heavily overloaded.
I understand that computers require a voltage of about 110V or 240V according to how they are switched. Also I think I am correct that monitors require a voltage around 240V (and cannot be switched to take 110V).
I imagine that the power required by a computer is about 50W, and a monitor about 100W. Is this correct?
Before we realised that the voltage of the supply had dropped so low we sent out a UPS capable of delivering 240V for input voltages of between 180V and 300V. This did not drive the computer. However when used in series with a voltage regulator it was possible most of the time to get the required voltage, though clearly this is not an ideal arrangement.
We would like to consider a satisfactory arrangement for 20 to 30 computers, though we cannot see how we would pay for such a system, especially as we are raising the £5000 for the library. However any advice you can give us would be much appreciated. Indeed to be realistic we will probably have to be satisfied in the short term with a system which will supply one or two computers.
We have considered:
1. Provide each computer with a UPS capable of delivering 240V if the supply is 130V or above. We hope that would work, but have yet to learn from the school if the voltage is mostly above 130V. This costs about £120 per machine, and the battery would perhaps need replacement every two or three years.
2. Provide each computer with a battery charger, a 12V battery, and an inverter to supply 240V ac. This is in effect a home made UPS and may not cost any less that a UPS. The battery would perhaps need replacement every two or three years.
3. Provide a petrol/diesel generator. To supply all the machines this would need to supply about 5kW. The cost to us would be prohibitive, and I suspect that fuel cost and correct maintenance would both pose problems. A simple generator costing say £250 would probably supply one or two computers. Someone suggested that the variation of the generator supply frequency causes problems, but since the computer itself is running on dc it is difficult to see that this would be a problem?
4. Use solar panels. This would be extremely expensive, and maintenance could be a problem, but we have considered this for one or two machines in the long term.
I would be very grateful for any help you can give. Should you need any more information do let me know and I will endeavour to supply it. Maybe we can get you a VSO job at Armitage then it will become your problem!!!!!
All the best, Mike.
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