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Highest power offline SMPS in plastic enclosure (no fans)

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Advanced Member level 5
Jun 13, 2021
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After several hours searching, i find the highest power SMPS i can find in all plastic , fanless enclosure is the LPC-150 from meanwell...


However, it is only allowed down to 180VAC minimum. Also, it must be derated in power when VAC goes below 200VAC....being only allowed 120W at 180VAC.
Also, it has overtemperature shutdown without saying where this temperature is measured.

Do you agree, you cannot get above 150W offline in plastic , fanless enclosure?

This one is all-plastic and fanless...

...and claims to do 280W from 100-265VAC......but its a laptop charger, and who knows, it probably only charges at that rate if the internal temperature is low? may well derate down to 100W as internal temperature rises.
Also, what external case temperature would the following metal cased, 150W SMPS get to when at 100VAC and full load, and in 40degC ambient temperature. ...Would you scald yourself if you touched it?

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Indeed most of the questions should be answered by the name plate and/or operation manual.

Btw: I don't expect the voltage to drop with increasing temperature. I'd rather expect it to switch off on overtemperature.
Several reasons:
* if you have an electronic device rated for xx voltage and the power supply just drops the voltage, it may cause malfunction
* within an PC/laptop there are switch mode regulators (POL) ... reducing the input voltage then means increasing the input current .. which is counter productive for power dissipation.
* even if you use POL linear regulators inside the load (PC/laptop) .... reducing the input voltage will not reduce the current ... and not reduce the power dissipation in a meaningful amount.

Usually these power units don't drive resistive load, where: I = V / R.

This is totally different to chargers. They often use some kind of current regulation. So on overtemperature they drop the charging current which also reduces the power dissipation. And the battery won't go to malfunction on reduced charging current.

Thanks, agreed, though AYK, if vout went 48 to 47.5v the current wouldnt increase much.....and from what i can see...that PSU is made for that zbook anyway? they could have arranged for the increase in current.

I think the "elephant in the room" here is that......

QUOTE>>>>>>Plastic casing is massively beneficial to customer, because it doesnt burn their hands when they touch it, so why havent Meanwell, TDK, Recom, Traco, XP, Artesyn, Murata, Mornsun, etc etc, done a "100-265vac, 150w+ and totally sealed plastic SMPS" ? <<<<<<<UNQUOTE
--- Updated ---

And thanks for your replys...i have also put the quesion to Meanwell , and await, (hopefully), a reply.
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Although the said companies are serving a different market, your assumption is wrong, see e.g. Meanwell GS220 series. Took me 15 seconds to browse the catalog.

Thanks, you are correct, it must be the highest power SMPS in plastic case in the world? (except chargers and led drivers as discussed)
At 100VAC and 45degC ambient, it must be derated down to ~187W.
Its 95% efficient so is best in class.....and yet still needs the derating.
It really does show that any more than 220W in sealed plastic is going to be really pushing it.

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Thanks, may i place the google translation here...?.....

[TRANSLATION] I may be late. The charger only needs to charge two batteries continuously, and the internal temperature meets safety standards. It is usually used in combination with target products and batteries. The adapter is run under worst-case conditions at nominal load until the temperature rises no longer and safety standards cannot be exceeded. So the nominal 200W adapter power is greater than the 200W charger. I have a 300W adapter that is 95.5% efficient at 56V output.[END OF TRANSLATION]
So the nominal 200W adapter power is greater than the 200W charger.
...thanks, this has been one of my own "highly held" beliefs also.
Efficiency matters "bigly". If you get to 110% efficient you can
do cooling. Heh.

How much of the plastic case has a thermal spreader behind
it, and so is in play for dissipation, matters. As do the qualities
of it (skinny sheet is not that effective, away from heat source).
I've taken apart adaptors and found a wee patch of aluminum foil
that somebody thought would make some kind of difference.
Plastic shapes are easy to get the way you want, if you put in
the thought & effort. Not everybody does.

Thickness of case and case material loading w/ thermally
helpul constituents, can help.

An aluminum case where most aluminum is not in the heat
path, might be inferior to a well engineered metal / plastic

Prismatic metallic cases are for people who don't eat crayons.
Consumer equipment has that constituency and so must use
plastic to keep from getting sued into insolvency.
Perhaps there are differences in people's understanding of the heat sink. I just feel that the focus is on how to control the heat source to not emit too much heat. If the heat source does not generate much heat, it means high efficiency, and there is no need for a large radiator. And some places inevitably have higher temperatures than others, leading to safety hazards. Therefore, it is necessary for the heat sink to first complete the task of temperature balance, and then diffuse the temperature. At least the power design of the plastic shell is considered in this way (personal perspective).
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