VFD-fans

[scott lipscomb]

I have two kinds of VFDs in my shop. One kind is silent while plugged in, the other kind turns on a fan when connected to power, regardless if the motor that it controls is energized or not. Those kinds of VFDs get switched off when not in use (because the are noisy, and because they seem to be needlessly running a fan), so, when I want to use the tool, I need to turn on the VFD, then wait 4 seconds or so for the VFD to energize, then turn on the tool. The kind of VFD I like more is the kind that does not make any noise...I can just leave it "plugged in" and turn the tool on and off instantly when necessary.

The kind that runs the fan is also rated much higher, at 5hp, and maybe that is the nature of the beast...are there any single phase input, 5hp VFDs that are silent while energized, but not running the tool?

[Aaron Inami]

I suspect it is a factor of current. The smaller HP VFDs do not have to pull as much current. There are two things that generate heat in the VFD. One is the input diodes that convert A/C to D/C power. The second is the PWM transistors that generate the output pulses/current that drives the motor. When you are talking about a constant 15-19 amp current draw at 240V and 8-11 amp 3-phase output, this creates a massive amount of heat. My 5HP ATO VFD does have a cooling fan and it is definitely noisy, but it's not on all the time. It only starts when I hit the "FWD" run button on the VFD to drive the motor. After I stop the motor, the cooling fan runs for about 2-3 minutes and then stops. The heat sinks on the side of the VFD definitely heat up fast (within 10 seconds of running the motor).

If there was a 5HP VFD with no fan, I think it would be significantly larger and weigh about 60-80 lbs just for all the heat sink required to dissipate that heat.

[Jared Sankovich]

You should be able to program the fan to run on demand. The default on the fugi drives is fan on all the time. It's a 1 parameter change to make them on demand.

[Michael Schuch]

My understanding is that VFD's can be left powered without any problems.

For me it might be a week or even two between when I get to use my shop so I prefer to power them off at the end of the day. I have push button on/off switches in front of my VFD's so I can power them off easily, i.e. not have to unplug them. I also have indicator lights that show if the VFD's have power (the VFD controls are not always directly viewable) so I know if I have left any on when I turn the lights off. I have occasionally left a VFD powered on, mostly before I added the indicator lights, for a week or more with no adverse effects.

On some of my machines I have my VFD's completely encased in and enclosure with auxiliary cooling fans in the enclosures (metal lathe and milling machine). I put the on/off push buttons on the face of the enclosures on these machines.


These push button switches work well for me:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

2022-10-16_113850.jpg

P.S. There is a huge variety of VFD's available. I am not surprised to hear that some always leave the fan running and some only power on the fan when needed. I guess I would worry about a cheap fan on a cheap VFD dieing a premature death because the fan is running 24x365. I would expect the VFD to throw an error when the fan was not functional. The majority of the cheap VFD's are based on a very few VFD control chips which I would expect to have a fan is running input.

[Thomas Marr]

I have a very cheap ($170) "10 HP" Vevor VFD (probably made by Isacon) and the fan runs only at VFD power up and when driving a motor. I expected it to run all the time as this is a common complaint I'm seen often regarding cheap Chinese VFDs.

I just came across a video on this issue on YouTube (How to make a SILENT Huanyang Variable Frequency Drive). I haven't watched it though and I'm not endorsing his approach. In fact, any approach to bypass the always-on fan has risks, depending on your level of skill. It's probably cheaper, and safer, to just replace it.

[Aaron Inami]

I just came across a video on this issue on YouTube (How to make a SILENT Huanyang Variable Frequency Drive). I haven't watched it though and I'm not endorsing his approach. In fact, any approach to bypass the always-on fan has risks, depending on your level of skill. It's probably cheaper, and safer, to just replace it.

I watched through this video a bit. He's adding a temp sensor circuit with relay that turns the fan on/off when it hits a temp threshold. It's a good solution if you have an electronics skillset. Just keep in mind he is using a drill press as the motor load, which is typically a very low HP and very light load. It doesn't take much to ramp up this motor and there is no resistance on the drill unless you are doing a 1" hole in heavy wood.

A Dust collector will have pretty much 80% or more load on the motor as soon as you start opening blast gates. Also, a 5HP motor is very heavy internally and the large impellers are also very heavy. This takes a LOT of current to ramp up the motor and your VFD cooling fan needs to be running immediately. The 5HP dust collector motor is going to use 3000-4000 watts constantly.

[Chris Parks]

I watched through this video a bit. He's adding a temp sensor circuit with relay that turns the fan on/off when it hits a temp threshold. It's a good solution if you have an electronics skillset. Just keep in mind he is using a drill press as the motor load, which is typically a very low HP and very light load. It doesn't take much to ramp up this motor and there is no resistance on the drill unless you are doing a 1" hole in heavy wood.

A Dust collector will have pretty much 80% or more load on the motor as soon as you start opening blast gates. Also, a 5HP motor is very heavy internally and the large impellers are also very heavy. This takes a LOT of current to ramp up the motor and your VFD cooling fan needs to be running immediately. The 5HP dust collector motor is going to use 3000-4000 watts constantly.

My Clearvue 1800 Maxes out at 16 amps for about 2 seconds on start using a VFD and that could be reduced by slowing the ramp time of starting. Though it is 240V I don't consider that current draw a huge amount and it runs at under 10 amps with one gate open because there is only one of me. We can get damned hot summers here, over 40 degrees is common and the fan mod as per the video has only triggered once to my memory and that is running at a constant 70hz. My situation is a bit different now I come to think about it as the blast gates themselves start the DE when they open triggered by the machine being used.

[scott lipscomb]

Aaron, I want my VFD to run the way yours done-fan on demand. Jared, I checked all the perimeters, then went to the internet-Huanyangs do not have the option for changing how the fan comes on, as others have alluded to. I went out to the shop to poke around on the VFD...I would happily operate on the unit and plug the fan into another one of the ports, however...I powered on the VFD and it made one last clicky sound, then died. I think I am in the market for a new VFD (unless someone can help me revive the dead)

So...Looking for a new VFD that can handle the motor nameplate as below. Its a bandsaw, and I need motor braking. Any suggestions? And, oh yeah, I want the fan to be on demand, or at least configurable!

IMG_5590.jpg

[Aaron Inami]

If so, this is the VFD I use for dust collector. I'm assuming you have 240V single phase as input. It does support a braking resistor wiring.

https://www.ato.com/5hp-vfd

There are other VFDs available in the 5HP range, but they are a lot more expensive. Let me know what your budget and power source requirements are if they are different than what I assumed.

[Jared Sankovich]

19FLA gets expensive with a fuji drive, prices are $100-150 over last year.
https://www.wolfautomation.com/ac-dr...0aAl3aEALw_wcB

[scott lipscomb]

Yeah, I suspect that I may have been running over current on my last VFD and that was what killed it. It would start acting weird when I ran the saw hard. I wonder, too, if motor braking takes a toll. Yes, 240(ish) single phase in. That ATO seems to indicate that it would meet spec, and as an aside, the product spec does offer some interesting bits about "rotary sushi", but doesn't look, from the side of the world, anyway, that it is as robust as some of the offerings that you suggest, Jared. Hmmm...I think I am inclined to throw down the $300 on the ATO and hope for another 2 or 3 years but I would also like get a drive that will last at least 1/10th the lifetime of the machine. I had a back up VFD, and either cheaper Huanyang that it is running on now, but it doesn't have motor braking, which I really want. Going to do a little more research...Thanks for the input, will post when I find a resolution.

[Aaron Inami]

Be careful what you look for. The VFD that Jared posted a link to requires 3-phase input. The ATO is the middle of the road in price. There are others, but they go up to the $600-700 level.

https://www.grainger.com/category/mo...&filters=attrs

https://www.wolfautomation.com/produ...-7_5_hp-10_hp/

https://www.ato.com/single-phase-to-three-phase-vfd

[Jared Sankovich]

Be careful what you look for. The VFD that Jared posted a link to requires 3-phase input. The ATO is the middle of the road in price. There are others, but they go up to the $600-700 level.

https://www.grainger.com/category/mo...&filters=attrs

https://www.wolfautomation.com/produ...-7_5_hp-10_hp/

https://www.ato.com/single-phase-to-three-phase-vfd

That vfd is rated for single phase input. Fuji doesn't make a single phase only vfd above 3hp/12fla. However all their 208/240v 3ph drives are dual rated for single phase. That particular drive is 15hp/47fla on 3ph input but only 21fla on single phase input.

I run one of the larger fuji drives 20hp (7.5hp) on one of my shapers. Note the factory dual rating of 60fla 3ph and 27fla single phase
20200404_113147.jpg

[Aaron Inami]

yeah, I missed the fact that it's 15HP at 3-phase.