# VFD Mounting



## ddickey (May 7, 2018)

PM 935TS Mill. I bought the Hitachi WJ200 VFD.
If I have to use an enclosure I'll mount that on the wall and run power to the mill with controls there. That's going to be approximately 15'.
Ideas?


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## 4ssss (May 7, 2018)

Make a backing plate and mount your VFD and switch on it together. That's how I did my lathe and Bridgeport.


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## ddickey (May 7, 2018)

Is it enclosed or open?


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## magicniner (May 7, 2018)

I've been running an open VFD on my Myford Super 7 for around 20 years, it's high enough and far enough from the chips that it's suffered no injuries ;-)


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## ddickey (May 7, 2018)

Based by the amount of grit, grinding and welding dust I find everywhere i'm not sure that is a good idea. That sure would make things less complicated though. I found and appropriately sized box on eBay i just bought for $20. We'll give that a go I guess. Some fuse blocks will also go in there. A power supply would be nice too for the DRO.
https://www.ebay.com/itm/HOFFMAN-A-161208LP-STEEL-WALL-MOUNT-ELECTRICAL-ENCLOSURE-16X12X8IN-D570068/382177193913?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649


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## Nogoingback (May 7, 2018)

If the VFD is mounted inside a box, there has to be some provision for ventilation: the fan on the VFD has to be able to move air through the
heat sink. It looks as though the enclosure you linked is pretty much sealed.   My VFD is wall mounted off to the side of the lathe where I can reach it, but out of the line of fire from oil and chips and it never
seems to get dirty at all.  It seems to me that the home hobby environment is usually clean enough to do without an enclosure, whereas in industry,
VFD's get mounted in all sorts of environments where enclosures are needed. And, if you do enough grinding/sanding/welding close enough
to contaminate your VFD,  you may be getting grit on your ways as well.


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## Dave Paine (May 7, 2018)

The Hoffman box is nice for controls and power supply, but it does not have ventilation for the DRO unless you cut out some holes.


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## dlane (May 7, 2018)

This is what I did for my mill, it has a computer fan in the bottom pushing air in for ventilation, remote controls on front.


Not the prettiest but works good.


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## mksj (May 7, 2018)

An enclosure is often needed for additional connections, fusing, power disconnect and sometimes for a braking resistor (depending on the type). A fan cooling system may be needed, depending on the VFD efficiency/dissipation, cabinet material, volume/radiating surface area and operating conditions.  My mill 3Hp VFD has a factory steel cabinet with no venting that is 12x22x8, the fan comes on when the VFD is running the machine motor/off when idle. I have seen sizing a VFD cabinet for no ventilation quoted something in the range of ~4sq in/W of dissipation for a sealed steel enclosure or ~1 sq ft/Hp, but there are other factors that need to be considered. It is a simple matter to cut a few holes in the cabinet and add a filter/fan to the VFD cabinet when using a smaller cabinet. The last 3Hp VFD mill system build I did, I used a 12x20x8 metal cabinet with no venting, anything smaller I would have added cooling vents/fan. IF adding a fan, then a plastic enclosure is a bit easier to cut holes in using a large hole saw or jig saw. 

*Non Ventilated Enclosure*
Non ventilated enclosures rely on the heat being dissipated through the walls of the enclosure. The better heat conduction of the enclosure the more heat dissipated. For this reason metal enclosures are far better at dissipating heat than plastic enclosures.

The power that can be dissipated in a given exposed surface area is:
PESA = k x S x △T
PESA: Power dissipated from within the enclosure via exposed surface area in W (Watts)
k: Heat transfer coefficient [sheet metal ~ 5.5W/m2K, plastic ~ 3.5W/m2K ]
S: Corrected enclosure surface area of the enclosure, in m2 in accordance with IEC890.
△T: Temperature differential (inside enclosure - outside ambient), in °C

Due to the distance of the VFD cabinet to the machine, I would recommended shielded cables at least for the control inputs/speed and do not tie them to the motor cable.


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## ddickey (May 7, 2018)

Could run the motor cable through conduit. 
Kind of rethinking as there is a nice large flat surface on the back of the mill. This would probably be the better idea I would think.


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## markba633csi (May 7, 2018)

I think the shorter the wires from the unit to the motor the better. 
M


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## mksj (May 7, 2018)

You could use flexible armored cable, I do not like to use rigid conduit to a machine. An alternative is to use liquid tight flexible metal conduit  and pull stranded wires.  I think you would be better off just getting shielded motor cable designed for use with VFDs. The cost is about the same, Automation Direct now sells it by the foot (minimum is 20'). The shield is grounded only at the VFD end, at the motor end cut back the shield and insulate it against shorting with black tape or heat shrink tubing. I uses high quality copper with nylon insulator eyelets at the motor end and for grounds, locking forked crimps at the VFD power/motor terminals. You need a good crimper to fasten the crimps properly.  On some builds, I will use 3M heat shrink insulated crimps. You could use 14AWG for 3ph 3Hp motor, but I prefer to use 12AWG, the cost difference is nominal.
https://www.automationdirect.com/ad...le_Control_Cable/12_AWG_Shielded/MCTC-12-4S-1


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## ddickey (May 8, 2018)

I was thinking about mounting it on the back, or front side of the access panel to the knee column, to the coolant reservoir. I have no plans to run coolant other than my mister.


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## Kiwi Canuck (May 23, 2018)

Did you end up mounting the cabinet on your mill?

Not sure if your saw my install, I installed the cabinet on the side of the column, I did this because it was the only place I could make it fit as I didn't have room behind as the machine is against a wall and the Z DRO scale is on the other side.

https://www.hobby-machinist.com/thr...ady-to-start-lathe-mill-shopping.51470/page-5  Starts at post #126

I removed the access panel and mounted it over the opening and was able to use the existing holes without drilling and tapping any new holes.

It worked well, the only thing I would redo is relocate my master ON/OFF switch as it's hard to reach when the table is raised and toward the rear..

I should have installed it on the door.


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## ddickey (May 23, 2018)

No not yet. I'm going to try mounting just the VFD to the inside of the access (coolant) panel. Probably will end up mounting something like yours though. Bought a remote operator, on the fence about if I'm going to use it or not.


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## Kiwi Canuck (May 23, 2018)

ddickey said:


> No not yet. I'm going to try mounting just the VFD to the inside of the access (coolant) panel. Probably will end up mounting something like yours though. Bought a remote operator, on the fence about if I'm going to use it or not.



That's a great idea and I saw someone else mount it inside the column, I did consider that but had already purchased the enclosures so went that route.

Not sure how far along on the install/planning stage you're at but just a heads up, if you run a 4 wire power cable, (3 + Ground)  you will be able to have 240 and 120 VAC on the machine to plug in lights, DRO, and Power Feeds, keeps the install tidy and reduces the need to run extra wires back to the wall.

If you look at my picture above I have Red and Black for 240VAC and White and either Red or Black to get 120VAC.
All three enter the box at the bottom right and go through the rotary switch, the 240VAC for the VFD goes through the 30AMP fuses, then to the terminal strip.
The White wire goes through it's own single pole breaker then to the white terminal strip.
I also have a 3AMP double pole breaker for a future 240VAC coolant pump and a 24VDC Power Supply for the fan, digital tachometer and LED lights.

I'll use the empty flex conduit for the 120VAC to a quad outlet at the back of the machine, I was going to mount it on the enclosure but after cutting the holes for the fan/vent, I had no room left so will use an external route.

David.


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## ddickey (May 23, 2018)

David. I didn't wire my 240V receptacles with a neutral so that option won't work. My mill sits below a 120V receptacle so everything that is 120 will have to come from there. I just need to get some cable glands and I should be ready to fire it up. Probably won't be until the weekend.
Nice looking control box, I may still do that at a later date.


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