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Thread: 3ph to 3ph VFD

  1. #16
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    Quote Originally Posted by Stustoys View Post
    Hi Shed,

    If you've got it, give it a go. It depends what you have in mind for the low speeds. With a HSS flycutter you might be happy enough, a 20 tip carbide face mill maybe not so much.

    I'm not so sure you have a sensorless vector control VSD there..I'm sure others will be able to tell you.

    You can set the freq as high as you're game. Though depending on the motor you're not likely to get more than about 100hz and even then its not likely to have much power. Its said that the rotors and bearings are the same for 1400 and 2800 rpm motors so it should be OK to run up to 100Hz on a 1400rpm motor....

    Stuart
    sensorless vector control makes a bit of difference then ?

    VFD cover.jpgVSD foreword.jpg

  2. #17
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    Quote Originally Posted by jhovel View Post
    I just found a really cheap vector control 2.2kW VFD - but only for single phase....
    http://www.ebay.com.au/itm/111378577196
    380/415V is more expensive.... e.g, this 1,5kW one... http://www.ebay.com.au/itm/200955092480
    Have a look here Joe, this guy might just use a different terminology for SVC ?

    http://www.auctiva.com/stores/viewst...14&styleid=106

  3. #18
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    Hi CBA,
    what's your background in these things? Just curious, not questioning your knowledge! Please don't be offended!
    It is a wealth of information and full of gems and great opportunities to learn for all of us.
    Occasionally I wonder if some of your statements are based on specifications rather than first-hand experience....
    You say
    And will run far too rough below about 12 Hz to be of any use at all, even for low power tasks.
    WhHat makes you say that, please?
    My experience with now nine V/F inverters and lots and lots more 3-phase motors (none of which are VFD suitable specified) does not match your statements at all.
    I machine happily at 6Hz on my lathe and sometimes even lower on my mill, my drill runs fine and able to drill precision holes at 8 or so Hz and other machines I use or have used to 'make do' run perfectly well over a much larger speed range than you state. All of my current motors bar one run perfectly good at 120Hz and one of the smaller motors I have spins to 180Hz....
    I just can't find any consistent correlation between your knowledge and my experience. Sorry.
    I read all your contributions with great interest and enthusiasm but...
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  4. #19
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    Quote Originally Posted by shedhappens View Post
    sensorless vector control makes a bit of difference then ?

    VFD cover.jpgVSD foreword.jpg
    Crap, I didn't read the text in the photos of the eBay ad properly - but then neither did anyone else.All our comments are way off! You have got yourself a bargain. This IS a vectorless drive and should work like a charm! If you got it at the price the eBay ad showed, you did well!

    I just went to the company website and translated the pertinent information, You are on a winner!
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  5. #20
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    Quote Originally Posted by cba_melbourne View Post
    If it is not a sensorless flux vector VFD it will not deliver much power below about 20Hz - still good enough for low power jobs such as reaming/countersinking etc, but not for serious cutting. And will run far too rough below about 12 Hz to be of any use at all, even for low power tasks.

    By all means, give it a try and get a feel for it. But my prediction is, you will come back and restore a two or three speed gearbox or belt drive to it.

    You can also try to go for a motor with more poles, if there is space for it that is. Because motor of a given HP get bigger and heavier the more poles they have. If your current motor was say a 4pole, and you can find an 8 pole of same power, it will be two frame sizes larger. But it turn at half the speed. Cutting your top speed in half, but doubling available power at any low speed compared to the 4pole motor.

    To help you getting a better idea what to expect:
    - as a rule, VFD drives are constant torque up to base speed, and constant power above base speed
    - base speed is usually 60Hz, sometimes 50Hz for some older motor model.
    - a common (not VFD rated) motor is constant power from base speed up to about 70 or 80Hz, then its shaft power drops to zero at about 120 to 130Hz
    - non vector VFD's are only constant torque from about 20Hz up to base speed, torque drops off rapidly below 20Hz. In a machine tool they have a useful speed range of about little more than 4:1
    - sensorless flux vector VFD's are constant torque from about 3Hz to base speed, torque remains useful from almost standstill. In a machine tool they have a useful speed range of about 6:1 and up to 8:1 with a perfectly matched VFD rated matched motor
    - power is torque*speed, or HP=torque*rpm.

    Thanks CBA, you are always a wealth of knowledge and have a talent for sharing it.

    "By all means, give it a try and get a feel for it. But my prediction is, you will come back and restore a two or three speed gearbox or belt drive to it."

    I suppose that if I do have to gear it down just to make it work for the time being it probably won't
    really matter, it will still work and I rarely have ever used it at high rpm anyway.

    shed

  6. #21
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    Quote Originally Posted by jhovel View Post
    This does not look like the eBay VFD you linked to. Is this the one you bought? If so, all our comments are way off - I hope!
    This description DOES look like a sensorless vector drive. SHould work like a charm! If you got it at or around the price the eBay ad showed, you did well!
    yup, its the one

    This whole VFD thing has had me right out of my comfort zone

    "If so, all our comments are way off - I hope!" That gives me hope

  7. #22
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    Sorry, mate, I edited my stupid last post while you were quoting it.....
    Please let us know how you go! You are one of few of us with an actual vector controlled drive.
    I for one would love to know how you find it in use!
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  8. #23
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    Quote Originally Posted by jhovel View Post
    Sorry, mate, I edited my stupid last post while you were quoting it.....
    Please let us know how you go! You are one of few of us with an actual vector controlled drive.
    I for one would love to know how you find it in use!
    I for one would like to know how use it

    spoze i'll wire it up and flip the switch........then get someone to read the manual for me

  9. #24
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    Quote Originally Posted by shedhappens View Post
    spoze i'll wire it up and flip the switch........then get someone to read the manual for me
    Yep, that's pretty much my approach.. works most of the time.

    Nice work getting a vector drive at a bargain price.. you will have to enable that function and look for an autotune function to "tune" the vfd to your motor charactestics.

    But....

    Having done all that and you'll get full motor torque across the speed range, you still won't get the same as having a gearbox... a gearbox MULTIPLIES the torque, a vector drive just means you don't lose too much.

    Still, it will save you lots of gear changes and belt swaps..

    Ray

    PS Did you ever use that 5hp motor for anything?

  10. #25
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    Quote Originally Posted by shedhappens View Post
    I had thought about cooling at low speeds, I thought that I would cut out the fins on the existing fan cover and mount a 240v fan.
    I'd like to put a temp switch on the motor somewhere to switch it on.
    I wouldn't bother with a temp switch - the amount of power a fan will draw compared to the motor is minor so I'd have it on all the time whenever the motor is on. Perhaps have it in parallel with a machine light?

    Michael

  11. #26
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    Quote Originally Posted by shedhappens View Post
    Hi Michael,

    I had thought about cooling at low speeds, I thought that I would cut out the fins on the existing fan cover and mount a 240v fan.
    I'd like to put a temp switch on the motor somewhere to switch it on.
    Where ? The between the fins at the top I suppose, it would have to be insulated from the fan air ?

    shed
    Hi Shed,

    Install the motor & VFD first and run it at low speed for a realistic length of time and then feel how warm the motor gets. You may not need extra cooling as long as you are not cutting at low speed for a long period of time. The motor on my mill barely gets warm at low speeds but I typically only run it for a few minutes for each cut and I'm not running it all day. As Joe says, suck it and see.

    Simon
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  12. #27
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    Quote Originally Posted by RayG View Post
    Having done all that and you'll get full motor torque across the speed range, you still won't get the same as having a gearbox... a gearbox MULTIPLIES the torque, a vector drive just means you don't lose too much.
    Yep, that's the point I was trying to make in my first post.

    The only way to get a torque increase at low Hz is to increase the motor HP in the first place regardless of vector VFD or not. Now it appears the OP's mill has back gearing in which case things are not so bad - he gets that mechanical advantage.

    I don't recall what spindle type he has, if he's said, but I do know that I'd be reluctant to attempt a 45mm hole in my B/port even though it goes down to 78 rpm (I think, I'm a long way away ATM). The holding ability of an R8 collet would make me hesitate. If the machine has a more capable taper spindle, 30 or 40 taper or similar, no dramas. MT4, fine. MT3, well, I wouldn't - there's a reason drill bits this size have MT4 shanks.

    PDW

  13. #28
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    Quote Originally Posted by jhovel View Post
    Hi CBA,
    what's your background in these things? Just curious, not questioning your knowledge! Please don't be offended!
    It is a wealth of information and full of gems and great opportunities to learn for all of us.
    Occasionally I wonder if some of your statements are based on specifications rather than first-hand experience....
    You say
    WhHat makes you say that, please?
    My experience with now nine V/F inverters and lots and lots more 3-phase motors (none of which are VFD suitable specified) does not match your statements at all.
    I machine happily at 6Hz on my lathe and sometimes even lower on my mill, my drill runs fine and able to drill precision holes at 8 or so Hz and other machines I use or have used to 'make do' run perfectly well over a much larger speed range than you state. All of my current motors bar one run perfectly good at 120Hz and one of the smaller motors I have spins to 180Hz....
    I just can't find any consistent correlation between your knowledge and my experience. Sorry.
    I read all your contributions with great interest and enthusiasm but...
    It probably depends what you expect and what you do with your lathe, and how big a lathe you may be thinking. I only own two of these old technology V/Hz VFD's. And that is where my practical experince with V/Hz drives used on machine tools end. Here my practical experiences with V/Hz VFD's to help put what I say in correlation to what you have found:

    My first VFD was a German Lenze-8200smd of 1HP. I bought it new in 2002 to upgrade my EMCO lathe. With it I bought a 3/4HP 4-pole motor from AEG. Both bought from an electrical shop in Melbourne (there was no eBay back then). Cost me $517, plus $130 for an IP rated enclosure. The best thing I ever did to my lathe, the best spent money on any lathe accessory. I was very happy with what I had done. That was before there were all these metalworking forums where one can exchange experiences, people had to do such things on their own, at their own risk and peril if it will work well or not. I did keep the 6 speed pulley setup with it. I have used this setup for about 7 years, that is why I can positively say it hat not enough power below 20 Hz for serious cutting. But it was fine down to about 10-12Hz for low power things like chamfering etc. It depended a bit where one did set a parameter that increased motor current at low frequencies. If this was set to give more power, the motor would run jerky and erratic when loaded at a frequency below 10Hz. About in 2009 I replaced this Lenze VFD with a Siemens micromaster vector of only 0.5HP (still driving the 3/4HP motor). The lathe definitively performs much better with this at speeds below 20Hz, and is usable down to virtually standstill (or about 3Hz). At speeds above 20Hz there is no difference with the old V/Hz VFD. I still use the good old 1HP Lenze V/Hz drive on my Waldown drill press, where it now drives a 1HP 4-pole GMC motor and I love it, for me it improved several times on the usefulness of this drill press.

    The other V/Hz VFD I have is a little special. It is a tiny 0.1kW Yaskawa Varispeed V7 which I bought on eBay NOS from France for peanut money. You see, my first lathe some 30 years ago was a Japanese Toyo Sakai ML260 with a nice milling/drilling column attachment. The same machine can still be bought today under the name Proxxon. Anyway, I sold the lathe 20 years ago but kept the milling column for my EMCO lathe. Then some 10 years ago I bught a Sieg X3 mill, and that meant I did not need the milling column anymore. So I made it into a miniature drill press for PCB ans small holes. And that is where this 0.1kW Yaskawa VFD comes in. I salvaged from a discarded distillation device a 1/10HP 3 phase motor that now drives my Toyo drill press with variable speed.

    Chris

  14. #29
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    Quote Originally Posted by RayG View Post
    Yep, that's pretty much my approach.. works most of the time.

    Nice work getting a vector drive at a bargain price.. you will have to enable that function and look for an autotune function to "tune" the vfd to your motor charactestics.
    Quote Originally Posted by jhovel View Post
    You have got yourself a bargain. This IS a vectorless drive and should work like a charm! If you got it at the price the eBay ad showed, you did well!
    You won't be disappointed with the PowTran drives. They are a great drive for the price.
    SV control is selected at parameter F00 = 1 and the Auto tune Ray mentioned can be found at parameter b11.
    I have a manual here if you need a hand when you get it up and running.
    If you punch in the motor nameplate details in parameter group b it should run straight out of the box using the pot and buttons on the control panel.
    Built: a Bench,a Desk,an Archery Display,

    Those were the droids I was looking for.

  15. #30
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    Thanks Chris for your frank validation of your experiences. What it shows is that we both share very similar VFD experiences but mainly with very different sized motors. That might explain our two different perspectives. I have only ever run a 1/2 HP motor with my first VFD - and that was on my Waldown NH where it obviously ran at only high or very high speed. My other VFD experiences are all between 1 and 5Hp motors, whihc have probably enough rotor inertia not to be bothered by very low frequencies.
    As a result, I have never found any need to invest in a vector drive - although I would like to.
    My first one incidentally was and still is (ran it today to show SimonL my surface grinder briefly stalled project) a Telemechanique Altivar 1.5kW that I got second hand about 1996 or 7 (they were about $5000 new) for $50 because no-one including me knew what they were. My brother the electrician happened to work where they decomissioned it at the time.
    Since then I have only regularly used the 3 Huanyangs regularly for about 8 or 9 years now. I have two Siemens V/F 1/2HP drives and a Eurotherm to use with small motors for my SG table drive and wheel feed eventually.
    My experience with the recently acquired 2 Hengtai's is still too limited to report much other than they seem to be quite well made for the price.
    I'd ;love to try a Vector drive on my CVA lathe - alas it will have to contend with a Hengtai or Huanyang...
    I guess we need to both be mindful of our different perspectives when helping others get their equipment.
    Cheers mate.
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

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