Huanyang 2.2kw fan direction question

[Doddy]

Having a fan drawing air into the enclosure creates a rather localised fast air-flow that would increase the probability of drawing dust, dirt and chips into the ensure at high speed, and depositing this onto the PCBs/electronics. Drawing air out of the enclosure (exhaust) allows the sourced air to be collated from the various air inlets at lower pressure differential and is therefore less likely to draw detritus into the enclosure.

Chosing an exhaust solution - the logical positioning is on the top of the enclosure to remove the hot air at the top of the enclosure.

Regardless, the controller IP is poor on these and they need protection within an external enclosure - though I don't practice this myself.

[Voicecoil]

Having a fan drawing air into the enclosure creates a rather localised fast air-flow that would increase the probability of drawing dust, dirt and chips into the ensure at high speed, and depositing this onto the PCBs/electronics. Drawing air out of the enclosure (exhaust) allows the sourced air to be collated from the various air inlets at lower pressure differential and is therefore less likely to draw detritus into the enclosure.

I see your point, but I think you also have to consider what's best in terms of cooling. In something like a medium>high power VFD likely 90+% of the heat will likely be generated by power devices on the heatsink, therefore primary concern need to be generating a fast turbulent airflow passing over that, easiest way is fan at the bottom end with a baffle/wall over the top of the fins to stop the air taking a short cut. Yes, you could do this with distributed inlets and sucking, but it would then involve a certain amount of baffles/ducts to direct the flow to where it's needed, which would likely make the unit bigger.
The point about crap getting into the unit is a good point though, and makes @marbles 3KW unit sound even stranger, as taking in air from the bottom has to be the best place to avoid that. I put my VFD in the cabinet when I built it and even added mesh screens on the cabinet ventilation to keep chips/swarf out, and am heartily glad I did as the surrounding floor looks like it's been snowing aluminium at the end of a machining session.