I am building a small system that includes two Meanwell LRS-100 series power supplies:
https://www.meanwell.com/Upload/PDF/LRS-100/LRS-100-SPEC.PDF
Note the photograph on the first page of the data sheet, and the drawings on the last page showing threaded holes along one edge and on the bottom of the unit. I would like to mount the units standing up vertically (on the flat bottom of my chassis), with the narrow edge (with 3 screw holes) downwards. From Meanwell's documentation, it is unclear if this is permissible, and if so, how performance might be de-rated.
Their one-size-fits-all installation manual:
https://www.meanwell.com/Upload/PDF/Enclosed_Type_EN.pdf
… states "Mounting orientations other than standard orientation or operate under high ambient temperature may increase the internal component temperature and will require a de-rating in output current. Please refer to
the specification sheets to receive the optimum mounting position and information about the de-rating curve."
But the LRS-100 series data sheet (the first link above) contains no such information. Telephone tech support confirms that the unit must be installed within the end-system, and that the system must contain 3X the volume of the PS, and that ANY orientation is acceptable. The agent did not inspire confidence, and I find this improbable: e.g. with the large flat side with ventilation holes facing downward, and the solid side (with two screw holes) facing upwards ?!?
So I seek guidance as to whether my vertical orientation is acceptable, and if so, how much de-rating might be required.
Best Answer
If your enclosure has side and bottom vents then the advice you were given makes sense to me. Inverted with bottom and side vents.
i.e. Convection air intake rising and exiting up past hotspots to vent outside with thermal conduction to top cover from baseplate..
In a design I did with 180W open frame PSU in 1U high enclosure, I used side vents with thermal controlled fans using a thermistor epoxied to the hotspot, ferrite transformer. It ran silently to 45'C up to 100W output to ext. load then fans started slowly to limit sense temp to 55'C but never ran full RPM at room temp.
If you mount it vertically then your convection air flow must not be allowed to rise over the hot spot to exit. Otherwise, a 40mm plenum fan may be needed.
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