For a new observatory in the Andes at 17,000 feet, we need to provide power continuously for 4 months. Requirement is 208VAC, 3 phase, 10 kW. The site is accessible by large truck, but connecting to the power grid is out of the question. We are thinking diesel generators and large fuel tanks. Any suggestions out there? Thanks.
Your solution may be more simple than you think. (a) An electrical machine will not fail at high altitude. The only concern you need to have is sufficient cooling of the machine. At high altitude, the air density is less, but the temperature is cool in addition. But then 10kW is not much at all to be concerned with heating. (b) Get an assembly done at a workshop so that you can run a belt off your truck axle to your generator shaft. (c) Drive the generator (make sure you have anchored it safely to the ground) from the axle of the truck (whose driven wheels you have raised with a jack). Start your truck and power up your generator. (c) 10kW is less than 14HP. This means your truck (200HP?) will not even have to be driven hard to generate the torque to give you full power for your generator. (d) You may need a separately excited DC source (lead acid batteries) for the field of your alternator if you don't use a permanent magnet rotor.
Check with the manufacturer, they will have derating tables habdy. You would probably need something approaching 30kW. You need to know what the generator can actually handle. Some generators need to be used at a minimum percentage of rated load to operate properly and reliably. Caterpillar have a section that deals in generators. Because of the remoteness reliability would no doubt be an issue. Go for a known name brand.
Are there any issues with the high altitude? You may need to modify the generators to work that high. 17,000 feet is really up there! Have you considered fuel cells? Wind power may also be an innovative solution.
As most of the answers' say. A diesel / alternator set would be the best solution. The diesel engine must have a turbo charger to allow the engine to operate successfully at that altitude. However, I doubt that the engine would need to be rated at 30kW it may need to be somewhere around 15-20kW to drive the alternator into a standing load of 10kW. Generally I size the alternator at 1.25 of the standing load, so the alternator would need to be around 15kVA, provided the power factor is around .8. You will need to have an electrical engineer to check your load factor and determine what P.F. can be expected. If your load has several variable frequency or DC drives, this could cause a low PF. Therefore the kVA rating of the alternator would be higher. Also at the altitude, cooling of the alternator could be a problem due to the thin air. The generator manufacturer may be able to provide an oversized fan assembly to compensate for this. Best of luck, your quest is very interesting. Source: Electrical Engineer (ret.) with 40+ yrs. experience
