Two Pentz cylcone motor questions

[Tom Trees]

Hello everyone
It's about time I started getting some dust extraction sorted.
I have been looking to get a flange mounted 3 or 4HP motor for a long time with no avail.
I've some experience by now, with wiring up VFD's to three phase motors, which I used on bandsaw/tablesaw.

On a recent thread, I was told I could de-rate a 3hp tablesaw motor to 2hp to use one VFD for the two tablesaws I have.
I chose not to, but it raised another question for me.....

I figure I am using close to the max voltage concerning my supply on this house.
I don't know for sure, but It seems like a good idea to think about a 4hp motor for an extraction system,
as Bill Pentz recommends a 5hp system.


Sher if it's too much, I can de-rate the motor to 3hp anyway... right?


And my other question is about the lack of flange mounted motors available.
I'm doing this on a shoestring, so I am way more frugal than most ....stubborn as a mule too.

I will be making this cyclone on a big heavy frame ...I have a hoard of metal that I can weld up.
So whats the story on using a foot mounted motor for this application ? ...

Would it be possible, if welded up a beefy bracket, to bolt a foot mounted motor to,
so in essence it would be flange mounted then ?
I'm guessing a big plate in theory, would be needed to fit the motor casing inside, as to not reduce shaft length?

Or could I make some plate on this beefy frame enclosure to bolt the foot mounted motor to ?

Just thought I'd ask since I've been seeing some motors recently for sale
Thanks folks
Tom

[Bill Dufour]

Voltage should not be an issue on a normal house. How far is your house from the pole?
Look for c-face motor. have you considered a belt drive setup. It would allow fan rpm changes with available horsepower. A vfd for a fan is overkill since you do not really need the variable part.
\Bill

[Tom Trees]

I am running these machines off a 13a plug and a 30a MCB.
The lights go dim when I start my 750w single phase pillar drill for instance.
Single phase is a no no for me.
I have not seen a proper cyclone with belt drive, and I'm presuming there is a reason for this.

Tom

[Adam Herman]

you use current, not voltage. voltage for a house should be constant enough, unless you are a mile from the transformer. i would use a belt drive setup with a couple pillow blocks for bearings if i was rolling my own DC.

I think you may need a little electrical education.

are you running your vfd's off of 110v or 220v ? what is the amperage of the main breaker to the house?

[Tom Trees]

Hi Adam
You are probably right, current, not voltage ....although I won't get into that.
The house supply is 60A and as i said my shed is a 30A MCB.
Running these machines off 230v :rolleyes:

All I can find is flange mounted cylcones
Has anyone here made a cyclone in the method you describe?
Tom

[Tom Trees]

I take it there's nothing wrong with de-rating a motor ....
Otherwise I would have got told off :)
So many reasons to go with a VFD
Tom

[Dan Friedrichs]

I think you're misunderstanding motor ratings.

A 5HP motor will only draw 5HP of power if you're putting that much load on it. If you build a dust collector with a 5HP motor and seal the inlet tube shut, it will draw almost zero power. If you open the inlet very wide and remove any restrictions on the outlet (filters, etc), it will draw much more power (potentially more power than the motor is rated to handle continuously). Nothing about the motor rating prevents it from drawing less (or more) power. It's just the maximum it should handle continuously.

So when you design this, if the motor draws more than its nameplate rating, just restrict the airflow. There's no need for a VFD.

[Tom Trees]

Hi Dan
I think there is defiantly a need for a VFD in my case.
I don't have three phase so the single phase starting current would blow the fuse in my 13a plug
I might not be able to handle a 4hp either.
So the ability to have a bigger motor if I move to somewhere else (rented), and the ability to have a ramped startup
suggests I do.
Also I would be able to get the motor and VFD for cheaper than a single phase and not have to wait.
Single phase motors in Ireland are sought after and nobody wants to know bout 3 phase.
I have not decided how many runs I will have, as I am a bit of a machine hoarder....
this will not be in the equation yet.
I am a fan of designing mobile bases anyway :)

It seems that de-rating the motor is a viable option it seems,
and will enable me to go bigger in the future as I amass more machines.

Can de-rating provide a quicker ramp up time to get a motor running in certain circumstances ?

Anyone have a link, or put me on the right track to find a non flange mounted 3-5hp cyclone example ?
Tom

[David Kumm]

The only way to reduce amperage on a motor is to slow it down. When collecting dust, reducing speed can really reduce the cfm and make the collector mediocre to awful. Is there any way to deal with the real problem- too little service to the house? Any way to run a generator when you are needing amperage?

I'm not sure you wouldn't be better off with a direct to bag or filter system. A cyclone is great but adds sp so you need more hp and impeller diameter than with a direct bagger with oversize bags and short runs. Dave

[Chris Parks]

99% of Clearvues in Australia are run at 220V through a VFD, I developed the motor and VFD combination using a TECO 3kw motor. Reading your posts I do not understand what you are trying to achieve to be honest. An electrical motor demands current as load increases and uses less when it is under less load so I guess it automatically derates itself to suit the load. My impression is you are thinking about it the wrong way round, the VFD controls the ramp up speed and this in turn controls the motor's demand and limits the current draw. A 15 inch impeller wide open runs at around 13.5 amps and at idle with everything closed well under 10 amps, maybe four or five but my memory is vague on that. Every one of the CV's in Australia runs from a 15 amp plug with no reported issues. Your biggest problem is not going to be the motor it is going to be where you source an impeller from, I would worry about that first and the motor later on.

[Tom Trees]

Hi again
The startup will probably be the issue I would have the problem with, everything else can be changed.
As was said I can have less amprege with less runs, maybe even one or two runs as I am fond of machine mobility.
It would be nice to have the option if I move house to have more runs.

I am not sure what the impeller route I'm going, nor the size.
I know it would be nice to match impeller size with current and also shaft diameter, but I'm not afraid of starting all over again.
I have to source all materials before I decide how things are going to go.

No one has brought up de-rating a motor as a non option, so that seems to me like I'm getting a 4hp dual voltage motor.
Unless a 3hp falls into my lap.

Now has anyone built a Pentz cyclone without a flange mount ?....
I really wonder why, as it seems theirs a lot of folks with low ceiling basements would buy a cyclone, but don't due to height restrictions.
Thanks
Tom

[Bill Dufour]

with only 13 amps I do not think you can run a dc and a decent saw at the same time. if you are talking 240 volts single phase you are looking at about 4 amps per horsepower. that means total horsepower should be under 3. So maybe 1.5 horsepower for the saw and the same for the DC.This does not include any lights on in the shop.
Bill

[Tom Trees]

Thanks Bill
Sorry, I should have mentioned, as it probably confused lots of folks ....
I wasn't talking about running these both at the same time.
I probably would have to make some mini cyclone thing like Marius Hornberger for use at the same time with the machines.
The cyclone is for cleaning up after a few cuts at a time ...that kind of thing.
Maybe one day I can get a place with proper power and swap the 13a cable with 16a.
I won't hold my breath though :)

Tom

[Chris Parks]

I am not sure what the impeller route I'm going, nor the size.
I know it would be nice to match impeller size with current and also shaft diameter, but I'm not afraid of starting all over again.
I have to source all materials before I decide how things are going to go.

No one has brought up de-rating a motor as a non option, so that seems to me like I'm getting a 4hp dual voltage motor.
Unless a 3hp falls into my lap.

Now has anyone built a Pentz cyclone without a flange mount ?....
I really wonder why, as it seems theirs a lot of folks with low ceiling basements would buy a cyclone, but don't due to height restrictions.
Thanks
Tom

My apologies but I simply do not know what derating an electric motor is or how it is done or even why you would do it. Using the VFD and the load placed on the motor is what defines the current draw. It was me who did all the work to use the CV outside the US in countries that used a domestic supply of 220 - 240V at 50hz.

Before you go any further forget the electrical side and find an impeller, that will be your single biggest hurdle. The Asian machines all use a maximum of 14" and a BP cyclone because of internal losses should use a 15" impeller. He explains on his site why he went for a 5hp motor instead of a 3hp and in the US his reasoning is sound. In the rest of the world a 3kw motor is perfectly adequate as we in Oz have proved over many years. If you want PM me your email address and we can discuss this further offline.

[Tom Trees]

Thanks Chris
I only heard about derating a motor using a VFD on another thread recently.
I asked if it was possible to get a VFD wired up for 2 tablesaws ...

http://www.sawmillcreek.org/showthread.php?250821-Tablesaw-On-Off-Switch-with-VFD/page3&p=2645667
Basically,
I got the impression, I could derate the 3hp motor of one saw to match the other 2hp saw I have also.
It seemed that changing the max amp in the parameters was the only thing to do ...
I just figured this would have less of an starting/running current.

I have seen Matt Mattingley make his own impeller out of metal on the Canadian forum years ago.
And seen Marius's wooden one also
I just thought I'd be able to make do as I went along, and make some compromises probably.
I have lost out on two opportunitys to get some materials, and just figured this will happen no more
It's about the time to get stuck in.
Thanks for your time everybody
Tom

[Todd Willhoit]

Tom,
You are confusing the terminology. VFDs are often derated when a three-phase VFD is fed from a single-phase source. A three-phase VFD has six rectifier diodes on the input. When used with a single-phase source, only four diodes are used, limiting the overall current. As an example, a three-phase 3 hp VFD may be derated tor 2 hp when supplied from a single-phase circuit.

No one is addressing motor derating because it is not something one does. One can apply a 3 hp motor at a capacity below its rating (2 hp for example), but it is still a 3 hp motor. Likewise, an unloaded 100 hp motor may be "consuming" 5 hp in losses just sitting there under power, but it is still a 100 hp motor.

On the other hand, manufacturers specify motors with a Service Factor (SF). The average motor may have a service factor of 1.0, meaning it can operate continuously at 100% of its nameplate rating. Industrial and other special motors may have a service factor of 1.1, 1.15, 1.5, which correlate to continuous operation at 110%, 115%, and 150% of nameplate rating. A 10 hp motor with a 1.5 SF is essentially a 15 hp motor in disguise.

In your case, if you want to run both motors at 2 hp, fix the VFD settings for the 2 hp motor and a standard volts/hertz (non-vector control) mode. If you want to keep both motors at rated hp, the easiest way is to use a mechanically-interlocked reversing motor starter with an auxiliary contact. The "forward" contactor can power the 2 hp motor, the "reverse" contactor can power the 3 hp motor, and the auxiliary contact can be used to signal the VFD to switch motor parameters. One selector switch can control everything, although it would be smart to use some relay logic to keep either contactor energized until the VFD has decelerated.

[Dan Friedrichs]

Todd's got it right. The motor is not "derated" because you're using less than the maximum nameplate horsepower.

The nameplate HP rating is simply the maximum the motor can continuously draw. If the ducting, impeller, filters, etc, allow more than x HP of work to be done, the motor will try to do it, and it will overheat if you're loading it too heavily. The logical solution is NOT to use a VFD to slow the motor down, but to reduce the load on the motor (by restricting the airflow, etc).

If you had a 300HP car, have you "derated" it by only driving it at 20MPH? Of course not. Likewise, if you loaded a heavy trailer that required 350HP to move, the solution is to take some of the load off so that you have sufficient HP available to pull it. There is nothing about the HP rating of your car that physically restricts the load you can try to pull with it - just as there is nothing about the HP rating of a motor that controls how much work it can be asked to do.

[Tom Trees]

Hello folks,
I must say thanks again, for your most thorough reply's.
I took from the other thread a completely wrong impression...
I just wanted to hear what I wanted to hear. :o

So I suppose I will be looking for a 3hp motor so...
I wonder how much starting current, say a 14" impeller draws
I still think with everything closed off, this would be a lot easier with 3 phase and VFD.
Especially the way I'm gonna be using it ...turning on quite frequently, after saw cuts.

It seems that I will have to have have minimum load on this by not having long runs.
From what I've seen, most 3hp motors have a 24mm shaft, so I presume Asian 14" impellers use the 24mm bore ...
Anyway I don't want to be annoying you guys and drifting off topic...fire away if ye want though :)
I'll learn eventually ...


I still am under the impression that a flange mounted motor is used for a reason ...
Is it simply to cut costs, not needing pillow blocks and whatever else, more bracing and framing ?
I think people would still cough additional this cost up if it meant that they could put one of these in their basement.
I just would like to know if I'm going out of my way finding a flange mounted motor .... when I could be making this work in other ways.
Thanks again folks
Tom

[Chris Parks]

The starting current is defined by the ramp up speed set in the VFD. A 15" impeller on a 3kw motor draws 16 amps at 240V for about two seconds on the VFD we use without altering the ramp up speed. After that is reduces as the speed rises but I can't remember the figures.

A 14" impeller is not a good thing to use as the losses in the cyclone are too large. The impeller is the stumbling block everyone comes up against and I made that point above.

Why do you want to re-invent the wheel? What height is under the ceiling where you want to put this cyclone? Your two biggest issues are going to be the impeller and noise, until someone experiences the noise they do not understand how loud they are.

[John K Jordan]

The house supply is 60A and as i said my shed is a 30A MCB.


I am not a power expert or an electrician (except in Mexico). I have done my own wiring in three different houses and three shops and this is the way I understand it:

The capacity limit you have is most likely in your electrical panel and maybe in the wires in your service entrance leading from the utility lines. The wires from the utility can usually supply far more power than you can use.

Would it be reasonable to rewire your service entrance to provide more power to the house and then to the shed/shop? It might not cost as much as you might imagine.

45 years ago I had a small house with a limited capacity fuse box (not breakers) - I think it was a 30 amp box. When I built a detached shop I ripped out that fuse box, installed a 200 amp breaker panel, and rewired the house. (I did all the work myself so it wasn't too expensive.) I left the old box in place feeding the house until I had the new service entrance done. After inspection the utility just switched the lines from the pole to my new drop. I ran a temporary line to the old fuse box to keep the house powered until I had time to switch all the circuits.

Years later I bought this farm with a 200 amp breaker box in the house fed by a transformer on the property. When I built my new shop I did not run power from the house. Instead, I installed an external breaker box by the transformer and supplied 200 amps to the house and 100 amps underground to the shop and barn. Light dimming comes from the voltage drop from conductors that are too small for the electrical load. You can find on-line voltage drop calculators to help size the wiring. The size and length of the run determine how much voltage drop you will get from a given load. (If I remember correctly the usual "acceptable" voltage drop is 3% but I wanted 1% or less.) I based my calculations on supplying a full 100 amps to the shop.

My shop is 250' from my primary panel so I had to use fairly heavy copper to minimize the voltage drop. No lights dim in the shop even when my 5 hp air compressor and 5 hp cyclone cut on. BTW, I measured the current on the 5 hp cyclone and it drew about 14 amps at worst case when the blast gates were open. (The current is significantly less with all the blast gates closed since the impeller is running in reduced pressure and not doing as much work.) I also have HVAC, a 3 hp table saw, several other 220v wood working machines, plus some big welders and plasma cutter.

After using the 5 hp ClearVue with 6" ductwork for a few years I would personally hate to go to a smaller DC. Maybe I'm spoiled now.

JKJ

[Todd Willhoit]

I wonder how much starting current, say a 14" impeller draws

A standard efficiency motor started across the line at full voltage will draw 6-7x the nameplate current for a very short period of time. The starting current draw when using a VFD is entirely dependent upon the acceleration time you set in the VFD. I would start at ten seconds and see what happens. With the blast gates closed, you can probably keep the current in the low single digits until it gets to 50% speed and starts doing some work.

[Tom Trees]

Thanks again for your input
John, I'm defiantly not going to get electrical work done on the house as I'm only renting and their is no long term agreement.

Chris, interesting that you say a 14" impeller is no good.
I would have thought there was a formula for a smaller impeller relating to the diameter of the unit, to get a marginally smaller result.
I.e Bill Pentz's 5hp with 15" impeller compared to a 3hp with suitable impeller (guessing that's 14") = loss of 40 percent best case scenario (pulling this figure off the top of my head) So runs/run would made according to this rule.
I know I'm way off on the above , sorry for annoying you.

I have got to ask about reinventing the wheel statement
Guessing this is in relation to just buying a motor and jumping in, but if it's about the non flange mounted motor question
I'm just asking as I see some foot mounted ones go for cheap, and no suitable flange mounted ones in 2 or 3 years of looking.
I would not mind doing the stuff required to make it work ..I've got time
Thanks guys
I will have a look at some impellers and see what hurdles I encounter...
I guess I can figure out shaft diameter sizes and such,
Its gonna take some studying,
Tom

[Chris Parks]

Tom, go and read BP's site....several times as it will take that to absorb it all. The parameters and standards he set will move enough air to collect the sub micron dust particles that remain suspended in the air due to their low mass. The big stuff can be picked up with a shovel, it is the small stuff that causes health issues. There is way more information, studies with ongoing development work etc on the Australian forums, it is at this time the best information to be had on the internet. Nothing in any other forum and I have seen a lot of them comes even close to the information and study being done in Australia at this time and I think it is the only forum the BP ocassionally contributes to these days. Best of luck with it.

[John K Jordan]

John, I'm defiantly not going to get electrical work done on the house as I'm only renting and their is no long term agreement.


Sorry, I didn't see where you said this was not your house. Might be simpler to look for a new place.

[John Lanciani]

Thanks Bill
Sorry, I should have mentioned, as it probably confused lots of folks ....
I wasn't talking about running these both at the same time.
I probably would have to make some mini cyclone thing like Marius Hornberger for use at the same time with the machines.
The cyclone is for cleaning up after a few cuts at a time ...that kind of thing.
Maybe one day I can get a place with proper power and swap the 13a cable with 16a.
I won't hold my breath though :)

Tom

So if you're not intending to run the collector while you're actually making dust what is the point? If you're just going to use it to clean up after the fact why not just get and use a shop vac and skip the cost and expense altogether? A dust collector is designed the way it is so that it can move a large volume of air to capture and collect airbourne dust from a machine. To pick up dust that has already settled out a decent vacuum at a tenth of the cost works just fine (or better)

[Alan Schaffter]

I think Todd and a couple of other folks touched on it, but to clarify the discussion about "derating"- unless the specs say differently, when you run a VFD on single phase (assuming it will work on single phase. All VFDs will not operate on single phase) instead of 3 phase, the VFD specs change. It will no longer support the same hp. It really is a wrong use of the term "derate." You are not physically derating anything, the vfd simply will not handle the load. For example, if you have a VFD rated for 2 hp @ 3 phase, when you operate the VFD on single phase it will only safely handle a 1.5 hp (approx) motor so you must choose a smaller motor.