http://www.nasa.gov/centers/glenn/about/fs06grc.html
Plasma Contactor The Space Station arrays operate at 160 volts dc. When the arraysare producing power, the station structure will also tend to float to avoltage close to the array voltage. Under these conditions, the SpaceStation could be subjected to problems like arcing from its surface tothe surrounding environment. To avoid these problems, the structure hasbeen "grounded" with a plasma contactor.Image right: Plasma contactor that will protect the structure of the Space Station Credit: NASA The plasma contactor unit acts as an electrical ground rod toconnect the Space Station structure to the local environment andharmlessly dissipate the structure charges. NASA Glenn engineersdesigned, manufactured and tested the hollow cathode assembly, which isthe critical component of the plasma contactor unit. The hollow cathodeassembly performs this function by converting a small supply of gasinto ions and electrons and discharging this stream to space. Thestream carries with it the excess electrons that created the surfacecharge. On Friday, July 24, 2009 2:15pm, "Kurt Albershardt" <i...@es-ee.com> said: Check out Nott Ltd. [http://www.nottltd.com/lightning.html] http://www.nottltd.com/lightning.html I know a couple of RF engineers who swear by these and will not setup atower without them. We are looking at putting small ones on each endof every row on a large array next year. On 7/22/09 13:57 , [mailto:toddc...@finestplanet.com] toddc...@finestplanet.com wrote:NASA had a similar problem on the space station.They used (I think - research this) some kind of static discharge uniton the exterior of the station. Todd On Wednesday, July 22, 2009 6:13am, "jason pozner"[mailto:zzyyzz...@gmail.com] <zzyyzz...@gmail.com> said: Hey all, I am trying to figure out how to mitigate problems found with a 12v500w simple DC system without a ground. This system is at 14,500' onDenali (Mt McKinly). We experienced a somewhat "festive" fireworksdisplay on the 4th of July as static current from a storm seemed totravel through one of the antennae, and energized some radio equipment. There is no grounded conductor, as there is no grounding electrode, asthere is no ground to put it in. The camp is situated on about 500' ofglacial ice. The conductivity of the ice is questionable, and to makethe puzzle a bit more fun the camp is raised and taken down at thebeginning and end of every climbing season (Apr-July), though the siteis the same. The loads are primarily for communications for search andrescue purposes, and reliability, and simplicity are paramount. Ihave been exploring the avenue of a surge arrestorsThanks, and waswondering if any of you could make a recommendation on a product thatcan either be reset or cheap enough to have a few replacements on hand. Everything is flown in or carried to the site, and repair/replacementneeds to be simple enough so non-technical minded personnel can performand re-set the system. Thanks, Jay Pozner Nunatak Alternative Energy Solutions Crested Butte, CO (970) 349-3432 [mailto:nunatakene...@gmail.com] nunatakene...@gmail.com
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