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  1. powderblast
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    powderblast EF Member

    Location:
    hull
    Hi i have just bought a lathe which is running on three phase i have bought a vfd to run the lathe from single phase

    but i have a coolant pump that runs on three phase i have converted it to run on single phase but it appears to have a dip when running do any of you guys know what i need to do.

    here the video clip


    20171012_113802.jpg
     
  2. powderblast
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    powderblast EF Member

    Location:
    hull
    heres a pic of the motor plate on the suds pump

    20171011_144844.jpg
     
  3. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    So the lathe runs from the vfd but the pump does not, correct. How exactly have you "converted" it to run from single phase?
     
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  4. Rocboni
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    Rocboni Trainee Access

    Location:
    Scotland
    Looks like he's connected a capacitor across the terminals to create a phantom 3rd phase , usually the motor must be connected in delta but that doesn't look like a dual voltage motor so I would say that's the problem the motor will be running a lot slower than it usually does. Winding street must be intarnaly connected in star configuration as only 3 leads visible.
     
  5. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    Didn't see the capacitor!
    Well it will run but the efficiency and power will be reduced as the shift and/or phase voltage balance will never be correct by doing that.
     
  6. Rocboni
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    Rocboni Trainee Access

    Location:
    Scotland
    You can get away with it with a small dual voltage motor connected in delta, giving 230 to each winding, but that motor will only be getting 115- 120v per winding connected in star.
     
  7. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    He needs a single phase motor on it.
     
  8. powderblast
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    powderblast EF Member

    Location:
    hull
    Hi i bought this and this runs great just got it working only down side is you loose all the original controls on the lathe but it all run on three phase and my house is only single.

    putting a single phase motor on it would not of work because the electrics was all wire up for three phase

    s-l500.jpg

    20170928_142621_HDR (1).jpg
     
  9. powderblast
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    powderblast EF Member

    Location:
    hull
    Yes the pump is star only so i was told wiring it like this would only give me half the power which should be fine but my concern was the way it was running or is this common doing this will it run like this or just burn out??

    i thought it may be dipping in power because of the capacitor no big enough???
    im not sure i have never done this before just going of advice and forums.
     
  10. Rocboni
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    Rocboni Trainee Access

    Location:
    Scotland
    2.5 is a bit small, usually thy are about 40uf
     
  11. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    I think 2.5 is about correct for a 40w motor as you can base it roughly on 70uf per kw.
     
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  12. powderblast
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    powderblast EF Member

    Location:
    hull
    what would be causing it to have a voltage dip if you listen to the video i have uploaded you will hear it
     
  13. Rocboni
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    Rocboni Trainee Access

    Location:
    Scotland
    Looking at other forums that seems correct, not sure if using say a 3uf would improve things. You could try and find the star point of the windings and separate to you can connect in delta, things would be a lot smoother.
     
  14. powderblast
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    powderblast EF Member

    Location:
    hull
    i dont think you can change to delta maybe if you strip the full motor down maybe????

    IMG_1730.JPG

    IMG_1730.JPG
     
  15. Rocboni
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    Rocboni Trainee Access

    Location:
    Scotland
    Yes you would have to strip it down to find the star point, it would have been made with 3 sets of windings so there will be a star point, it could be there as soon as you take the top off. Just depends how able you are, you could then reconfigure internally and bring out the 3 leads as it is just now.

    It seems to be pumping sufficiently anyway, you'll never need that kind of flow for coolent on the lathe, it'll empty before it's drained back. You'll use it once and it'll be everywhere, I hardly use my collect pump, only if it's stainless steel I'm turning.
     
  16. powderblast
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    powderblast EF Member

    Location:
    hull
    its was they surging it was doing im concerned about the flow is ample i think you will have to turn it down
     
  17. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    Can't you wire a supply from the lathe.
     
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  18. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    Why do you think it is star and not delta connected.
     
  19. Rocboni
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    Rocboni Trainee Access

    Location:
    Scotland
    Never considered it to have 400v windings connected in delta, wouldn't that be unusual for such a small motor?
     
  20. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    Don't know to be honest.
     
  21. Rocboni
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    Rocboni Trainee Access

    Location:
    Scotland
    I would bet on it being star connected, larger motors above 5kw delta 400v star 690v from my limited experience.
     
  22. powderblast
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    powderblast EF Member

    Location:
    hull
    I have left it running for around 30mins and the temperature of the motor got to around 40degree no hotter so i think ill just leave it alone it never stopped, did slow down but i think it will work fine as is.
     
  23. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    Seems to be fine, have you tried it with no fluid running through it. Not for too long, might need it to lubricate the pump.
     
  24. Marvo
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    Marvo Gender Confused Staff Member

    Location:
    South Africa
    There's so many factors at play here that finding the best cap size is going to be hit and miss, I'd try a 3.5uF and see if it's any better.

    Might be a good idea to fit a klixon type device rated at maybe 80 Celsius, there's a good chance that motor's going to run armer than its winding class permits if it's running for extended periods.

    KSD301 N/C 80 degree 15A Thermostat Temperature Switch Bimetal Disc - KLIXON | eBay - http://www.ebay.co.uk/itm/KSD301-N-C-80-degree-15A-Thermostat-Temperature-Switch-Bimetal-Disc-KLIXON-/141682953211
     
  25. marconi
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    marconi Regular EF Member

    Here is a link to a static phase converter which someone in a welding forum has used to run a 0.05hp (0.05 x 750 = 37.5 W) three phase motor coolant motor like yours. It switches in a boost capacitor for the starting phase using in this case a push button but an arrangement using a time delayed relay and its contacts could make it automatic.

    rotary phase converter wiring schematic - Google Search - https://www.google.co.uk/search?q=rotary+phase+converter+wiring+schematic&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiIt-fX0e3WAhXCuRoKHZdaCqUQsAQIJQ&biw=1640&bih=766#imgrc=qM-k0hCKK2k2_M:

    Static phase converters are not good at starting and powering variable and high torque loads. In your case I think there is some hunting or hysteresis happening caused by the interaction of the motor's torque speed characteristics and that of the pump and fluid's. Ie: Motor speeds ups - load torque increases - motor torque decreases - motor slows down - load torque decreases until point when motor torque begins to increase....and as the pump motor changes in speed so does the magnitude of the generated phantom phase.

    A way around this is to use a rotary phase converter. These use an unloaded 'idler' motor of say 4-5 times the power of the load motor to generate the phantom third phase in its windings. The load motor is then connected across the idler motor's windings viz L1 -L1, L2-L2 and Lp -Lp to be energised by the two supply lines L1 and L2 and the phantom phase Lp generated by the idler. This scheme allows the load motor to be powered by the idler and its inertia (mechanical and electrical) ie. the load motor to be motoring rather than be both generating and motoring at one and the same time. Or something along these lines.

    There are many 'how to' guides at the end of a google search. You need to be, or employ someone who is, competent in electrical matters, craft and safety to build one or perhaps buy one or have one made for you.

    ABB 3 phase motor. 0.18 kW 1370 RPM | eBay - http://www.ebay.co.uk/itm/ABB-3-phase-motor-0-18-kW-1370-RPM-/263243880545
     
  26. Rocboni
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    Rocboni Trainee Access

    Location:
    Scotland
    It would be a lot less hassle just to buy a single phase coolant pump. £100 on ebay
     
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    Last edited: Oct 13, 2017
  27. marconi
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    marconi Regular EF Member

  28. Rocboni
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    Rocboni Trainee Access

    Location:
    Scotland
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  29. marconi
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    marconi Regular EF Member

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  30. Rocboni
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    Rocboni Trainee Access

    Location:
    Scotland
    I sure hope so!
     
  31. powderblast
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    powderblast EF Member

    Location:
    hull
    the coolant pump runs fine left it on practical all day so im happy with the way its running and the vfd on the lathe is great m well happy i did contact qualified elections to do the job and no one was interested i eventually got some one from a motor rewind place but there was to much money the way the lathe is now is just as good as original i will be getting the safety shut working on it though.

    i am not a qualified electrician that is not my trade hence why im asking for abit of advice and all is greatly appreciated.

    thanks for all your input guys
     
  32. darkwood
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    darkwood It's all about Gmes Staff Member Electrician's Arms

    Location:
    West Yorkshire
    This is an electrical engineering project hence you struggled getting any electricians to get involved, I assume this is your own project and for personal use only as you have probably contravened so many regulations and safety standards here in converting this lathe that you will probably have put yourself at risk given an emergency situation, so just for my own curiousity here, since you have lost the original controls built to old standards and effectively upgraded the machine, how does the Emergency stop system operate, how does the lathe brake itself and if applicable the electro-mechanical clutch system work, making a control circuit functional is easy, making it safe to use takes a lot of knowledge and experience...
    I'm guessing this is a small lathe gauging the size of that motor frame but even so there is a lot of geared torque on the spindle and it could do a lot of damage with all respect in an emergency but as this is personal use you really don't have anyone to answer to so I only comment on it as an advisory note here in that you consider the consequences of dabbling in this kind of stuff, something you-tube often fails to mention if you are actively using it to get this lathe upgraded.
     
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  33. Rocboni
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    Rocboni Trainee Access

    Location:
    Scotland
    Most of these lathes don't actually come with Emg operating systems, or mechanical brakes as they are aimed at hobby use. My lathe came from a educational establishment and simply had a low level Emg button installed to drop out the start Contactor, I have a vfd installed now, the Emg button stops the lathe in about a 2Seconds, this is fully programmable.

    Come to think of it the lathes at school didn't have any automatic braking facility if an Emg button was pressed to actually stop the lathe immediately, other than a foot bar which cut the power and applied brakes depending on how hard you pushed on the bar.

    I have seen larger lathes with DC injection type braking installed.
     
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  34. darkwood
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    darkwood It's all about Gmes Staff Member Electrician's Arms

    Location:
    West Yorkshire
    The requirements for schools and colleges has changed dramatically over the last decade as far as I know, considering safety only extended to wearing googles in my school days it wasn't uncommon for kids to be injured on workshop machinery.
    I deal mainly with the large lathes usually 30kw upwards where you cannot achieve a stop on a dime piece without creating a larger safety risk so extra user training and awareness is usually needed, electromagnetic braking is usually the choice of larger lathes not DC injection, the issue with DC injection is it has a timed injection rate at a given voltage which is effective for known loads but lathes are variable in their loads and speeds so not suitable in most cases as damage to the motor could be done by simply changing the load or speed.
    The smaller lathes can be brought to a quick stop quite safely even when loaded up thus a moderate inertial load with limited risk of total mechanical failure like shearing the shaft which of course would present a higher danger than having a longer run down.
    As for my previous post, he is changing the controls of the lathe and thus anything he does must comply to the latest regulations, the size of the lathe is irrelevant here as even with the student sized lathes there is a risk or injury and/or death but like I said, it is for his own use and he is not selling it so he has no one to answer to if all goes Pete Tong and he is injured or worse. Imagine getting clothing caught by the spindle, there is more than enough torque available even when it is stopping to pull you over the lathe or under the spindle (rotation dependent) and often the outcome will not be pretty.
     
    Last edited: Oct 20, 2017 at 12:11 PM
  35. Rocboni
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    Rocboni Trainee Access

    Location:
    Scotland
    A young girl was actually caught in a lathe locally at a school, lucky it was not fatal, however she did suffer facial injuries, I think it was her tie which got caught. I'm only taking 5 years ago max when I was at school, there was a global Emg stop system but it simply cut power to all machines if any was activated, the school tech dept was built in 1997.

    I think you have to consider the circumstances, it's only going to be used as a hobby machine so he poses a risk only to himself, buy disconnecting the original control system and connecting to an inverter has not likely made it less safe then it originally was unless they machine guarding has not been integrated as it was when I converted my lathe.
     
  36. darkwood
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    darkwood It's all about Gmes Staff Member Electrician's Arms

    Location:
    West Yorkshire
    As I expressed, as this is a private project there is no real body that he has to comply to but like you touch on here, their are often electric clutch systems and/or braking that can be lost without you realising when you convert such machines, some lathes have mechanical clutching and some electrical this in itself has a great bearing on safety when upgrading the machine, I have seen this done badly so many times, I have seen Hi/Lo speed clutch control lost and compensated by overspeeding the motor thus leading to mechanical failure as excessive stresses are played through the gearing etc, I have seen drive clutches powered permanently to allow VSD control which means the motor starts up under heavy gearing and not what it was designed for, luckily setting up the drive can assist the starting and limit any damage caused by this.
    As for the girl getting caught in the lathe with her tie... it beggers belief that kids are allowed anywhere near such machinery with loose clothing, said school should be fined with the full force of the H&S, not sure what school this was but we all had to wear full overalls over our uniforms when in the workshop and that was 30yrs ago never mind 5yrs.
     
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    Last edited: Oct 20, 2017 at 5:30 PM
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