What's new
What's new

VFD in a enclosure. Other ways than this?

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
The box height is 20", width is 16", and 8" deep. The door has no buttons or lights yet. There is:

Breaker
Fuse block
230 to 115 VAC transformer
VFD with front panel removed (actually my spare VFD).
Far right connector is for 3/4" rigid conduit.
Two small connectors are for drive signals and shielded motor cable.

The manual says 3" above and below for free space. I'm planning to cut large vent holes in the top and bottom.
DSC_1009.jpg

The motor cable connector can be attached to the large box. Thus the shield of the motor cable has a ground point connection at the large box.
Or the motor cable can be brought inside the large box and terminated at the VFD terminals.
What would be best?

DSC_1010.jpg

The motor connection box. I would have to make a reducer type fitting that goes from 3/4" NPT to the straight thread on the existing fitting.

The thread length is too short on the existing fitting for much else. The piece in the middle is a fitting that has the 3/4" NPT thread needed for the motor box. The other side of the piece has it's hole too large for the thread of the connector. I would just make a new piece from some 304 laying around.

DSC_1011.jpg
 
Several issues. Regarding the venting, I would recommend a plate spaced 1/2" over the top to prevent junk from falling into the enclosure. Just having openings would violate the code and could allow metal pieces to fall on the drive. On the bottom, cover the openings with hardware cloth.

The shielded cable should be grounded at the drive. As far as the 3/4" NPT thread and a mechanical thread most conduit fittings are so loose that the taper would make no difference.

Tom
 
How about cutting out a square hole to view the VFD display. Or have access to the keypad with a swing away clear plastic door?
The way the breaker works is that to open the door the breaker is disengaged. So I don't have access while the VFD is on.

Just wanted to ask but I can always cut into the door later if needed.
 
How about cutting out a square hole to view the VFD display. Or have access to the keypad with a swing away clear plastic door?
The way the breaker works is that to open the door the breaker is disengaged. So I don't have access while the VFD is on.

Just wanted to ask but I can always cut into the door later if needed.

Just use one of the MANY VFD where the (all low-voltage..) display/keypad can be remoted - up to 10 feet or so, typically - with a standard flat cable, RJ-45 connectors.

Or add the maker's "bus" interface card - copper or fibre-optic - and locate the controls on the machine-tool?

Or a whole different continent if you feel a real need to "network". Old stuff already, All major makers.


There;s another option.... I got "hooked" on KB-Penta DC Drives that nearly all have the integral NEMA-4X sealed, die-cast case one can safely place right at the machine-tool.

Then KB started supplying VFD in the same style case. May not have been the first to do that, as a look around finds several others makers putting their VFD into similar cases - "washdown" rated, even.

Cost more, yes, those do. But all of them have the advantages of NOT requiring extra case-volume space, AND.... being covered under Warranty where a DIY case may go AGAINST a warranty issue.

2CW
 
Last edited:
Here's a VFD box I built for my son's southbend lathe. Did it so he can remove it to another lathe when he upgrades. below is the text from an old post:

Here’s a nice little project. I built an enclosure to hold a VFD and controls for my son’s new (to him) lathe. The unit is built so he can just wire 220 1 phase to the VFD and then the 3phase lathe wires to the lathe on the output side. If (when) he trades up in lathes, the box comes right off to be mounted on another machine.

The pics show the box I folded up and welded. There a little chimney below the VFD to direct air to the cooling fan. the bottom is perforated so the air can exhaust. i used an Allen Bradley on/off/on switch to provide forward/off/reverse control. The industrial quality pot provides speed control. the brake resistor is for fast stopping. I sat extras on the box in one pic to show these components. eBay was my friend here.

My son is electrically challenged, so I grabbed an old motor off the shelf and wired it up to test
programming of the Automation Direct GS2 drive.
GS2 Series Drives User Manual

Today’s job is finalizing the programming and then I’ll ask Milady to paint it.

karl
 

Attachments

  • VFD box 1.jpg
    VFD box 1.jpg
    95.8 KB · Views: 243
  • VFD box 2.jpg
    VFD box 2.jpg
    94 KB · Views: 315
  • VFD box done.jpg
    VFD box done.jpg
    96.2 KB · Views: 196
The box height is 20", width is 16", and 8" deep. The door has no buttons or lights yet. There is:

Breaker
Fuse block
230 to 115 VAC transformer
VFD with front panel removed (actually my spare VFD).
Far right connector is for 3/4" rigid conduit.
Two small connectors are for drive signals and shielded motor cable.

The manual says 3" above and below for free space. I'm planning to cut large vent holes in the top and bottom.
View attachment 260304

The motor cable connector can be attached to the large box. Thus the shield of the motor cable has a ground point connection at the large box.
Or the motor cable can be brought inside the large box and terminated at the VFD terminals.
What would be best?



The motor connection box. I would have to make a reducer type fitting that goes from 3/4" NPT to the straight thread on the existing fitting.

The thread length is too short on the existing fitting for much else. The piece in the middle is a fitting that has the 3/4" NPT thread needed for the motor box. The other side of the piece has it's hole too large for the thread of the connector. I would just make a new piece from some 304 laying around.

Several issues. Regarding the venting, I would recommend a plate spaced 1/2" over the top to prevent junk from falling into the enclosure. Just having openings would violate the code and could allow metal pieces to fall on the drive. On the bottom, cover the openings with hardware cloth.

The shielded cable should be grounded at the drive. As far as the 3/4" NPT thread and a mechanical thread most conduit fittings are so loose that the taper would make no difference.

Tom

The plate is a decent idea.... but it is not perfect.... crap falls on the un-protected top area next to the hole and cover plate, vibration moves it over, and it falls in. I do not like holes in the top.

It's too late now, but it is possible to put a VFD in a sealed box. A properly sized bix will have the surface area to keep the interior cool , given the heat loading from the VFD. Works fine, makes for larger boxes, which gives more wiring room and clearances. VFDs without fans may need a small circulation fan. ("cold plate) VFDs can be mounted to a heatsink that extends outside the case, but they are not available from all vendors)

Failing that, vents in the side near the top are good, and are easier to protect against crud.

That's a very small box, according to the picture. Your options are very limited with a box that small
 
It's too late now, but it is possible to put a VFD in a sealed box. A properly sized bix will have the surface area to keep the interior cool , given the heat loading from the VFD. Works fine, makes for larger boxes, which gives more wiring room and clearances. VFDs without fans may need a small circulation fan. ("cold plate) VFDs can be mounted to a heatsink that extends outside the case, but they are not available from all vendors)

Failing that, vents in the side near the top are good, and are easier to protect against crud.

That's a very small box, according to the picture. Your options are very limited with a box that small

Like this?
McMaster-Carr

It's not too late. Only hole made has been for the incoming power using rigid conduit.
I wouldn't want a box larger than 16x20x8 hanging on the wall.

To the box machinists out there. I find it difficult to cut holes and slots in large boxes. Mostly due to lack of rigidity with common work holding mechanisms.
If I could cut 4 or 5 slots in each side then I could weld louvers at 45 degrees over the slots.
 
Like this?
McMaster-Carr

It's not too late. Only hole made has been for the incoming power using rigid conduit.
I wouldn't want a box larger than 16x20x8 hanging on the wall.

To the box machinists out there. I find it difficult to cut holes and slots in large boxes. Mostly due to lack of rigidity with common work holding mechanisms.
If I could cut 4 or 5 slots in each side then I could weld louvers at 45 degrees over the slots.

What works well, fifty + years now, is to MAKE a box without bending or welding atall.

Stock Ell extrusions for a frame. Simple flat plate, all sides. Fasteners of choice.

Do any piercings & c. while still in flat-plate form. if not Greenlee "chassis" hole punches (or louver punches), then hole saws, annular cutter. Even milling.

2CW
 
Masking tape, drill and a quality jigsaw with a fine tooth metal blade will make short work of those openings. Clean the edges with a file.

SAF
 
I found some options which other folks might consider.

A old slide out tray computer case has a front aluminium grill with two identical louver sections. Could cut them into square pieces and bolt onto my box.
I have two other steel boxes with built-in louvers on each side. Could cut them off and bolt on my box.

You-tube videos.
A guy made a punch and die from scrap metal in 1 hour and made his own louvers. First he used a angle grinder with a narrow blade and cut the horizontal slots for the louvers.
Then he used a hammer with punch to form each louver. This was for the hood of a vintage car.

Another video should how is is done with a small press. The layout lines were done with a sharpie pen and that can't be too accurate. But the end result looked good.
 
The plate is a decent idea.... but it is not perfect.... crap falls on the un-protected top area next to the hole and cover plate, vibration moves it over, and it falls in. I do not like holes in the top.

It's too late now, but it is possible to put a VFD in a sealed box. A properly sized bix will have the surface area to keep the interior cool , given the heat loading from the VFD. Works fine, makes for larger boxes, which gives more wiring room and clearances. VFDs without fans may need a small circulation fan. ("cold plate) VFDs can be mounted to a heatsink that extends outside the case, but they are not available from all vendors)

Failing that, vents in the side near the top are good, and are easier to protect against crud.

That's a very small box, according to the picture. Your options are very limited with a box that small

The way to handle your complaint is to make the cover plate into hat shaped by notching the corners and bending the flanges down. Make the size such that there is a 1/4 to 1/2 inch gap around the the top and the edge of flange is 1/4 to 1/2 inch below the top of the enclosure. Acts like a drip shield.

Tom
 
The way to handle your complaint is to make the cover plate into hat shaped by notching the corners and bending the flanges down. Make the size such that there is a 1/4 to 1/2 inch gap around the the top and the edge of flange is 1/4 to 1/2 inch below the top of the enclosure. Acts like a drip shield.

Tom

Yeah, that works. Not a "flat plate" anymore, but.....

I've done enough autopsies on VFDs to have seen quite a few odd units..... like the one from the grinding room..... inside the circuit board was coated in fine metal dust.... which eventually arced over. Needed a better filter than it had on the enclosure air intake, there was no encapsulant on the boards other than the solder resist.

No matter what you do, someone manages to make better contaminants.
 
For a inlet port at the bottom I was thinking about a slide in/out tray with filter material. Then I could remove it and clean with air or soap and water.

Anybody have a picture or drawing of that approach?
 
For a inlet port at the bottom I was thinking about a slide in/out tray with filter material. Then I could remove it and clean with air or soap and water.

Anybody have a picture or drawing of that approach?

Don't get too carried away with filtration and guarding, else you may as well just use a large NEMA 12 enclosure with no openings.

I was faced with a similar problem back in the 1970's. GE was coming out with programmable controller. I was asked to design the enclosure. Must exist in a factory environment, no openings, no internal circulating fan. Max temp inside was ??(forget). Played with a number of designs, settled on a cast aluminum box with internal and external ribs.

Tom
 
Played with a number of designs, settled on a cast aluminum box with internal and external ribs.

Many folk have gone the same route, and for a seriously long time already.

For VFD, just look for NEMA-4X / IP-65.

If not in the budget to JF buy them that way to begin with, scout the salvagers for VFD, DC Drive, or anything else as could have its case robbed and adapted.
 
Cut some metal and this is how both sides will look. Thought about tack welding but I'm going to drill and tap for stainless button head screws

DSC_1015.jpg
 








 
Back
Top