# VFD ideas



## Michaeljp86 (Jan 29, 2013)

Im worried if I get a VFD it will die because of these condensation issues I have, also maybe cold temperatures in the winter. I was wondering if I could build a insulated box to put it in so sudden temperature changes wouldn't get it. Or do these things make heat during use so being inside a box would get it hot?


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## woodtickgreg (Jan 30, 2013)

Michaeljp86 said:


> Im worried if I get a VFD it will die because of these condensation issues I have, also maybe cold temperatures in the winter. I was wondering if I could build a insulated box to put it in so sudden temperature changes wouldn't get it. Or do these things make heat during use so being inside a box would get it hot?


They do make heat and if put into an enclosure they need to have cooling fans. Also teco does make a vfd that is in a waterproof nema enclosure and has heat sinks on the back side I believe, that is the one I will use. It cost a little more but will protect the vfd, mine is in a dusty environment.


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## rdhem2 (Feb 20, 2013)

Your VFD is not in danger.  

VFD's come in what is refered to as panel mount configuration.  Meaning they have absolutly no clue how you are going to employ it.  Therefore all VFD's need to be placed in an enclosure suitable for the working enviroment to protect the drive and personel who may come into contact the unit.  This is the reason most true industrial drives come with a removable key pad.  These keypads are then mounted near the operator workstation for convient use.  Choosing the correct keypad provides all necessary functions for drive operation, Forward, Reverse, Stop, Jog, Display Values, Speed Control etc.  Internal programming may or may not also be available.

Now enclosures:
NEMA 1     Protects from accidental physical damage, shields from falling dirt and debris.  No moisture protection.
NEMA 3R   Raintite, as it says, protects from falling rain and wind driven moisture up to a 45 deg angle.  Maybe lightly gasketed.
NEMA 12   Washdown, corrosion resistant stainless steel, heavely gasketed with continious hinges and clasping catches.
NEMA 4     Submersable for short periods of time, well sealed.  Can be sprayed with pressure for washdown.
These are of the top of my head so please verify for complete information.  

Heat yes, all VFDs create massive amounts of heat and dispell this wasted energy via huge heat sinks.  Mounting in an enclosure should be ensured by using heat transfer compound under the mounting feet for maximum cooling effect.

Cold does not affect a VFD under usual operating conditions.  Heat destroys electrical components and ruins conductivity.  Cold only enhanses electrical properties in all conditions I can think of.  To a point of course.  My experience was in commercial freezers down to -35 degrees F.  Add the fan blown air and the equivilent was probably below -100 degrees F.

Condensation, bad stuff.  Do all within your power to eliminate condensation.  They sell little tubes of dehydration compound that you replace every so often if you have the problem.  Unless you have a submersable enclosure a minimum of one 1/4 inch drain hole should be drilled in the low point of the enclosure.  Years of practice have shown me watertite enclosures keep water in better than out!  All that said no VFD should be mounted in the open.  They are not designed for such use.  If heat is a problem, vent kits, louvers, filters, and even air conditioners are available to stabilize enclosure enviroment.  And of course if cold does prove a problem heaters are available.  To help ensure the integrity of your enclosure use the proper fittings for the use.  Only punch holes in the bottom and lower one third of the enclosure.

When you complete your wiring pay attention to voltage clasification on the conductors.  Supply wire barriers in the enclosure to separate low voltage and line voltage wiring.  Separate line/motor terminal wiring from control terminal wiring.  Neatly land and bundle conductors suitably marked to simplify future troubleshooting and maintainence.  If you must intermingle low and high voltage conductors be sure all wire is rated for the highest voltage present.  No MTW (machine tool wire) mixed with computer wiring/ door bell wire.

When you size your enclosure be generous as the space disappears quickly.  Also remember that most requirements listed apply to continious duty equipment meaning it  will be in continious operation for four or more hours.  Less than that is intermittant operation and a whole different kettle of fish.  Like welders and craines and hoists for example.  Just gets simpler all the time.  Just wire and plan for continious duty and you will be covered.  

Nothing to this stuff, anybody can do it.  No problem.  "Ol Uncle Frank" says you don't need all this expensive rubbish, it will work without it.  UL and the authorities say different, I am merely the messanger.  As they say, pay me now, or pay me later.  Just because it works does not mean it is right or *safe*.


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