Electronics > Beginners
Streetlight LED driver is open to the air.......therefore needs confomal coating
ocset:
--- Quote ---Like TomS_ said, it's definitely not "open to the air" - are you under the impression that electronics used outdoors are all hermetically sealed or something?
--- End quote ---
Thanks, the thing is, all the off-the-shelf LED streetlight drivers are in totally sealed plastic enclosures….like this….
http://www.docs.lighting.philips.com/en_gb/oem/download/xitanium/Datasheet_Xi_LP_70W_0_2-0_7A_S1_230V_C150_sXt.pdf
…..so if , as I describe in the top post, you have an enclosure which is actually open to ambient air, (ie , not in a totally sealed plastic enclosure) then you are going to have electronics which runs a lot cooler…..and this means that all those off-the-shelf LED streetlight drivers are going to be far inferior in comparison. So what I am saying is, are there any disadvantages to not having a totally enclosed plastic enclosure?
I mean, this could put all those off-the-shelf, totally enclosed LED streetlight drivers into extinction…Do you agree?..and if not, why not?
T3sl4co1l:
A sealed plastic enclosure isn't the be-all-end-all. Moisture diffuses through plastics, slowly but surely. Eventually the humidity inside rises to match the average ambient humidity. If that level is high enough that, at the lowest ambient temperature, water condenses: the game is over, you've lost.
Potting isn't impermeable either, but it does take up space. Liquid water can't condense on a corrodable surface if there's no surface exposed!
Closed (but not sealed) enclosures are typical where dripping water is expected. Where a sealed enclosure will trap moisture, a vented one allows the humidity to equalize with ambient humidity. This doesn't prevent condensation -- ambient conditions can certainly become condensing -- but it does mean it's unlikely for humidity inside the box to be much greater than the ambient, day-to-day level. Add some conformal coating to take care of the occasional condensation, and you have a pretty good box.
This construction is probably typical of lighting fixtures, automotive components and so on.
IP67 and such -- sealed enclosures -- are used where water under pressure is expected. Pressure washing (often automotive and industrial), submersion and so on, are typical conditions. Condensation is usually less of a priority. All you need is a sealed box, and sealed connectors; a regular board can be placed inside. If long life and condensation is a concern, then it should be potted as well.
Tim
JS:
Also, street lights are on during night, so worm in the most likely co densation scenario.
If you have a kind of sealed box as you described, tight fit to the pole, and some water might come inside in a windy rain, for it getting out will be even harder, so you have another problem, I've found sealed enclosures filled with water much more than you imagine, so I prefer holes on the bottom and protected top, conformal coating and if possible good air ventilation in places rain can't get inside.
JS
Kjelt:
Outdoor driver electronics should be potted.
mzzj:
--- Quote from: JS on August 27, 2018, 07:09:12 am ---I've found sealed enclosures filled with water much more than you imagine, so I prefer holes on the bottom and protected top, conformal coating and if possible good air ventilation in places rain can't get inside.
JS
--- End quote ---
GORE has a product for exactly this problem: https://www.gore.com/products/gore-protective-vents-for-lighting-enclosures
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