Fan/Venting for a VFD Enclosure?

chefjuke · Jan 7, 2017

Hi,

I'm looking for a little guidance on whether what I am thinking of doing for my VFD enclosure is viable.

I am installing a Teco FM50 220v 1-phase to 220v 3-phase 2HP VFD to run my Grizzly Knee Mill. The enclosure is not particularly big and I want to include either fan or vent on top (with appropriate screening) to ensure the box stays cool. How to power the fan is what I'm wondering about. I can put in a 12v dc or 120v ac fan. In a perfect world, the fan would turn on when I turn on power to the VFD.....So....

I was wondering if it is feasible to use one of the incoming power feeds just past the power switch that ultimately goes to the VFD or is my electrically challenged brain misthinking this.

See crude diagram attached.

or am I just better of adding another line and switch just for the fan?

Or am I missing some other, easier solution?

Any help or suggestions greatly appreciated.

-CJ

JST · Jan 7, 2017

The manual gives the fan location and required clearances around the unit.

http://www.teco.com.sg/admin2/images/e-catalog/Manual Inverter E2(FM50).pdf

You can perfectly well turn a fan on with the same switch that provides power to the VFD. You need a 220V fan, or a way to power a fan at a different voltage, but it will work.

toolnut · Jan 8, 2017

I have had good results with enclosure volumes 4 times the vfd volume and no fan or venting required. It is a lot less hassle than a vent filter and vent fan.
Last one I did was a 1 hp 120 volt in x 240 volt 3 ph vfd for a bridgeport vee belt drive mill head. It has been in use for 3 years.

chefjuke · Jan 8, 2017

I probably should have been a little clearer in my original post.

I think what I am really wanting to do is use ONE of the two 110v lines to power a 110v fan inside the enclosure. Just not sure how this might affect, if at all, the rest of the circuit, or if it would work the way I envision.

If you look at my original diagram, it shows the two powered lines coming into the switch, with one making the detour AFTER the switch to the fan power. THAT's what I am most interested in getting some feedback on.

Thx,

awander · Jan 8, 2017

chefjuke said:
I probably should have been a little clearer in my original post.

I think what I am really wanting to do is use ONE of the two 110v lines to power a 110v fan inside the enclosure. Just not sure how this might affect, if at all, the rest of the circuit, or if it would work the way I envision.

If you look at my original diagram, it shows the two powered lines coming into the switch, with one making the detour AFTER the switch to the fan power. THAT's what I am most interested in getting some feedback on.

Thx,

The way you show it, the fan is in serirs with the VFD in one leg of the incoming AC power, and that will not work.

If you have a neutral coming in to the box along with the 2 hot legs, you would want to wire the VFD normally, then connect the fan to one of the hot legs, post switch, and to neutral.

Steve in SoCal · Jan 8, 2017

If your concern is an imbalance on L1 vs L2 to the inverter, wire a light with the same or close to same wattage on the other leg. A 100 watt fan on L1 and a 100 watt light on L2.

Steve

jim rozen · Jan 8, 2017

"...use ONE of the two 110v lines to power a 110v fan ..."

You can't do this unless you have a neutral brought into the enclosure.

Your options include:

1) 240 volt fan in parallel with the VFD.

2) 240 to 120 volt transformer to run a 120 volt fan.

3) No fan at all, using an enclosure meeting the thermal requirments above.

Does the Teco unit have an integral fan? Often these do. A ventilated enclosure
might work well. An inexpensive enclosure, hole saw, and screen, with a single
phase Teco VFD inside:

Steve in SoCal · Jan 8, 2017

Jim,

While I agree with your plans, why not bring in a neutral wire and forget the rest? When I got my Monarch 10EE it had 240 service going into it with a control transformer. In the disconnect for the drive the box also had 120 volts for the work light and a DRO. In relocating the control cabinet I rewired the controls to line voltage off the L1 and L2 legs and neutral. I still have the transformer it is simply not used.

There are a lot of 240 volt appliances that use a neutral. Industrial setting where there is no convenient place to get single phase 120 service it makes sense to supply a local source. A guy at home with a machine in the garage is a whole different matter.

Steve

chefjuke · Jan 8, 2017

Aha,

That's pretty much the gist of what I meant to ask (badly formed questions sent when I was tired). You've picked out the underlying concern I had.

Thanks!

chefjuke · Jan 8, 2017

Steve,

Thanks for the reply. This is what I'm leaning towards.

-CJ

chefjuke · Jan 8, 2017

Bill,

Thanks for your reply, albeit not particularly helpful and somewhat condescending.

While I realize that my original post may have not have been worded perfectly well, or that my request for guidance may have seemed a bit simplistic, I don't know why you felt the need to insult in your reply.

As my day job involves computer technical support I am well familiar with RTFM, but I also know that there are ALWAYS workarounds and alternate solutions for specific situations. I was looking for a solution that might allow me to do with what I have at hand (a slightly smaller enclosure than 'spec') as well as get other folks ideas on options.

Wasn't expecting a medal from NASA, just some ideas/feedback. Other folks seemed to have come through with exactly what I was looking for without the snark.

Surely you could find a way to respond to a forum query without being as insulting?

Cheers,

-CJ

jim rozen · Jan 8, 2017

"...why not bring in a neutral wire..."

Well there is that!

For some reason I had it in mind that he wanted to avoid using a neutral.
Of course this should have been *first* suggestion.

JST · Jan 8, 2017

It's a simple way.

But not all 240V runs have the neutral, and once the run is in place without the neutral, it is not always easy to add it. Depends on the wiring method used.

And fans come in all sorts of voltages. These days, with computer fans, and auxiliary supplies going to lower voltages, 12V or 24V are more common than 120V for fan power, so no guarantee that 120V would be any help at all.

chefjuke · Jan 8, 2017

JST said:
It's a simple way.

But not all 240V runs have the neutral, and once the run is in place without the neutral, it is not always easy to add it. Depends on the wiring method used.

All,

I have a few options and some of which I realized after the thread started so I'm just looking at how I want to wire it, whether I want to include the fan in the enclosure and my options for wiring the fan if I do.

The easiest answer would be, of course, to get a bigger enclosure that meets the specs listed in the manual and I may go that route to just don't like having to spend a chunk of money on an email enclosure that's an inch or two bigger in each direction of the one that I already have.

Yep, I know, I can "do it cheap or do it right", I was just looking for ideas on what might be possible and folks here have given me those.

Thanks!

– CJ

Sent from my iPhone using Tapatalk

chefjuke · Jan 8, 2017

chefjuke said:
All,

I have a few options and some of which I realized after the thread started so I'm just looking at how I want to wire it, whether I want to include the fan in the enclosure and my options for wiring the fan if I do.

The easiest answer would be, of course, to get a bigger enclosure that meets the specs listed in the manual and I may go that route to just don't like having to spend a chunk of money on an email enclosure that's an inch or two bigger in each direction of the one that I already have.

Yep, I know, I can "do it cheap or do it right", I was just looking for ideas on what might be possible and folks here have given me those.

Thanks!

– CJ

Sent from my iPhone using Tapatalk

This is what I have at the moment, we'll see what I end up with...

Sent from my iPhone using Tapatalk

Jraef · Jan 9, 2017

Where is the air going to come from that the fan is exhausting? With no inlet, the fan will do nothing.

One down side of having a fan is that you will be sucking in contaminants with the air flow. Screens help keep out the chunky stuff, but not the volatilized materials like cutting oil, moisture etc., hence the suggestions of using a sealed box with 4X dimensions, preferably metal (plastic is less thermally conductive). If you are in a clean room, don't worry about it but if you are next to a machine, it's a valid concern.

Of course, one option is to ignore that issue and run the VFD until something is dissolved or shorted by the contamination, then just replace it later,

JST · Jan 9, 2017

Looks pretty small.

They have no spec for a sealed enclosure, some others do give that,

Check the manual i=on hat same page again for the required airflow, they give locations for fan and vent. One presumes they know what they want and have reasons for that.......

chefjuke · Jan 9, 2017

Jraef said:
Where is the air going to come from that the fan is exhausting? With no inlet, the fan will do nothing.

One down side of having a fan is that you will be sucking in contaminants with the air flow. Screens help keep out the chunky stuff, but not the volatilized materials like cutting oil, moisture etc., hence the suggestions of using a sealed box with 4X dimensions, preferably metal (plastic is less thermally conductive). If you are in a clean room, don't worry about it but if you are next to a machine, it's a valid concern.

Of course, one option is to ignore that issue and run the VFD until something is dissolved or shorted by the contamination, then just replace it later,

There is a 3" hole with screen and filter on top above the fan and planning on putting the same on bottom for air intake.

This is in a home shop and the mill only gets intermittent use compared to an actual full-blown working machine shop, which is, in part, why i'm looking to make do with what I've got on hand. If I had the $$ and space, I'd just have bought the right nema box and wouldn't even be asking the question..

Sent from my iPhone using Tapatalk

chefjuke · Jan 9, 2017

Hi,

Yes, the teco DOES have a fan, was just thinking that the additional fan might be of use/needed due to the smaller case. Maybe not. Still chewing on this.

Thanks,

-CJ

JST · Jan 9, 2017

General rule on electrical enclosures is to make them at least half again bigger than it seems reasonable to use.

Or, of course, to use whatever is required by the NEC. That requirement may be "indirect", due to cable bending minimum radius, etc. In your case, there basically is no minimum for your size wires, so "big enough to easily work in there" is another way to size things.

I would judge that enclosure as clearly being below the "big enough to easily work in there" rule. Not a LOT below, but just a bit too cramped. You need for instance, to more easily see where the wires are going on the VFD. With too little space, you fail to spot the "wild strand" that is shorting to another connection, and the like. As it is, they are way down in there.

Of course there is also the issue of the manufacturer's requirement for ventilation. It really does not take a long time for electronic parts to overheat. Transformers and motors take considerably longer.

Fan/Venting for a VFD Enclosure?

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