Why do inverters have an altitude rating? - Page 1
Forum section: electronics / general

author: HannoB
author_rank: Contributor
timestamp: June 06, 2022, 02:51:35 pm
content: HIWhy do some inverter datasheets indicate a maximum altitude above which the inverter would... I dunno?...explode?... Derate?Cheers!

author: jpanhalt
author_rank: Super Contributor
timestamp: June 06, 2022, 02:59:42 pm
content: http://dynapowerusa.com/how-altitude-affects-the-design-of-power-supplies/https://www.edn.com/how-does-altitude-affect-ac-dc-power-supplies/

author: HannoB
author_rank: Contributor
timestamp: June 06, 2022, 03:04:14 pm
content: I see. Thanks @jpanhalt!

author: free_electron
author_rank: Super Contributor
timestamp: June 06, 2022, 03:15:36 pm
content: all electronics has an altitude rating. As air pressure decreases the standoff (insulation) voltage decreases. something that can isolate 1000 volt at sea level can only handle 600 volts at 1km above sea level.So precautions have to be taken when designing stuff for high altitude (especially for things like planes), but even carrying things up Mt Everest can be problematic... then again, we are talking about things running hundreds of volts. i doubt someone would be lugging an old CRT tv up Mt Everest with a long extension cable .... it would surely flash over...

author: Kleinstein
author_rank: Super Contributor
timestamp: June 06, 2022, 03:42:20 pm
content: The needed distance goes up, or the voltage rating down, though not that fast. It is more like a 10% reduction for every 1000 m.

author: coppice
author_rank: Super Contributor
timestamp: June 06, 2022, 04:26:46 pm
content: As well as the insulation issues others have described, when you get high enough other issues come into the picture. In unpressurised parts of aircraft you need to look at pressure differential issues with things like electrolytic capacitors. In some cases components degrade faster, in others they just fail.

author: f4eru
author_rank: Super Contributor
timestamp: June 06, 2022, 09:49:41 pm
content: - Insulation, especially clearance- Cooling- pressure effects (Mechanical).

author: HannoB
author_rank: Contributor
timestamp: June 07, 2022, 06:43:03 pm
content: how on earth do they design electronics to function on something like the new James-Webb space telescope where it is practically in a vacuum? I can just see those electrons misbehaving, almost like inside a vacuum tube.

author: coppice
author_rank: Super Contributor
timestamp: June 07, 2022, 07:05:48 pm
content: Quote from: HannoB on June 07, 2022, 06:43:03 pmPeople have successfully made electronics work in some extreme environments, like the Venus landers. However, you need to design for a specific range of environments, and the less benign that range gets, the higher the price gets. There is no reason for mainstream products to tolerate anything beyond normal shipping, storage and operating environments.

author: james_s
author_rank: Super Contributor
timestamp: June 07, 2022, 07:48:10 pm
content: Quote from: HannoB on June 07, 2022, 06:43:03 pmI suspect they use an inert gas fill rather than having the electronics exposed to the vacuum of space, I know at least some of the Apollo electronics packages were pressurized with nitrogen. There are also conformal coatings, epoxy potting, etc. And the voltages used in most modern electronics are pretty low.

author: RoGeorge
author_rank: Super Contributor
timestamp: June 07, 2022, 08:19:18 pm
content: For James Webb Telescope, the lack of air is a big problem in terms of cooling, in the first place. Even if it's very cold in outer space, the heat can be lost only by radiation, which is much less in comparison with the loss of heat by air convection, like we are used to have here on Earth at sea level.Higher altitude means less air, therefore less cooling by air convection, at least in theory. I don't know if in practice this really matters here, on Earth.

author: TimFox
author_rank: Super Contributor
timestamp: June 07, 2022, 08:24:14 pm
content: Quote from: coppice on June 07, 2022, 07:05:48 pmThere was an episode of the US TV series "The six-million dollar man" (Season 4, episode 14, Jan 16, 1977) where Steve joins forces with Soviet experts to stop a Venus probe, designed to survive in the harsh environment on Venus, which got loose and is wreaking havoc in Wyoming.