On Sat, 25 Feb 2006 14:08:14 -0600, Wayne
wrote:

The volume of air in the enclosure is irrelevant. What
you want to avoid is heat buildup in any part of the
controller. So if you flow enough air in and out
of the enclosure, the temperature in the enclosure
will be the same as the abient temperature outside the
enclosure. So air flow over the heat sink is important.
If there are vent holes in the controller for the rest of the
electronics, make sure air flows there also. Otherwise make sure
there is enough airflow around the whole controller to avoid
heat buildup inside the controller.

Wayne D.

On Sat, 25 Feb 2006 17:56:58 GMT, ~Roy~ wrote:

Well I have a box full of all kinds of muffin fans, some 120VAC and
snip

I put lots of vfd's in enclosures. Some are in classified areas,
others aren't. I use a free download from Hoffman to calculate
whether or not I'll have a problem. Here's the link:
http://www.hoffmanonline.com/Technic...adTherSoft.htm

Most of the time, it's not a problem, plus I monitor and alarm the
heat sink temperatures in my control software. Larger drives, or lots
of drives in one cabinet require more cooling.

In my Z-purged enclosures (flammable areas) I usually use a water
cooled heat exchanger. Just don't allow it to freeze. When we
shipped some skids back from out of state, the guys prepping for the
move didn't blow out the exchangers, so they froze and I had up to
three inches of water in a box with a bunch of electronics. We had to
drain the swamp then dry the boxes with fans. Actually, we didn't
lose anything except the exchangers themselves.

Pete Keillor