VFD vertical mounting or the VFD cops show up?

I've got a small enclosure where my intended VFD would fit if I mount it horizontal. It's got a cooling fan, but the manual insists on vertical mounting only, like all VFD manuals do. What gives? What harm could it do? Will the VFD cops show up??

Cooling airflow paths and effectiveness can get weird!

Your VFD was designed using the standard rules for proper airflow and effective cooling when mounted vertically. Then tested to verify proper functioning. The makers know vertical mounting works so thats what they advise. There are quite enough other things that can go wrong without potential odd effects due to inadequate cooling when mounted at "that" angle in an enclosure "that" size when the outside temperature is "this" and there is an r in the month.

With a decent cooling fan and enough airflow in the correct direction to simulate the flow when vertical mounted it will almost certainly be OK horizontal. But the operative word is almost. You'd need to simulate it to be sure. Not easy. Heck the makers didn't bother to simulate for vertical mounting. Following the rules works just fine on this level of job.

Buy a proper enclosure or make a box.

Clive

The other wild card is temperature controlled fans... They may use the natural convection until the fan is needed. In that case, the thing may heat up faster than expected before the fan kicks in if horizontal, and life may be shorter.

Many VFDs can be used either vertically OR horizontally. If they go to the trouble of saying vertical only, there is probably a reason.

Use an enclosure that allows that.

BTW, if the VFD only fits one way, the enclosure is probably too small and does not meet the size and clearance requirements..

In an enclosure, the heat is first transferred to the air, then to the enclosure, and finally to the air external to the enclosure. That requires a certain minimum area of the enclosure surface. Normally that is a spec in the manual as well, although it may be expressed "indirectly" as a certain clearance all around the VFD.

One point of order: there's typically a parameter that sets the fan to 'continous run' and I always set them up that way.

The responses tell me what I need to know, thanks to all. The fan is the first thing on with power up, full blast. Mount the drive horizontally and it will be fine. Or go thru way more expense and labor to rip out the
old enclosure, replace it with one that's 4" taller, re-install all the wiring, etc. I'll take my chances. It's
a simple old bandsaw. Max current on drive = 12 amps. Highest current draw I've observed at full load =
3.6 amps. I suspect the drive isn't going to overheat. If the NEC or VFD cops show up........I know Nothing!

The last box I worked on was 16W x 20H x 8D. Any sizes bigger and they get real expensive.
Probably if you need something bigger then the VFD is the box.

My god, whatever you do don't mount it horizontally, upside down. It'll explode!

jim rozen said:

My god, whatever you do don't mount it horizontally, upside down. It'll explode!

Click to expand...

Risky. But at least the phone is handy so authorities can be alerted in case of peril. If someone under 40 can figure out how to use it.

Western Electric space-saver.