Astro_Al Posted August 6, 2006 Share Posted August 6, 2006 Howdy. Anyone know anything about running a three phase machine (lathe) from single phase? I know it can be done, but that's as far as it goes! What do I need?... What's the damage likely to be?... ...and generally... Help! Ta, Al. Quote Link to comment Share on other sites More sharing options...
SOA 93 Posted August 6, 2006 Share Posted August 6, 2006 Howdy. Anyone know anything about running a three phase machine (lathe) from single phase?I know it can be done, but that's as far as it goes! What do I need?... What's the damage likely to be?... ...and generally... Help! Ta, Al. I know they are generally not the cheapest, but you could start at Machine Mart. http://www.machinemart.co.uk/ranges.asp?g=114&r=2105 Home made phase convertor came with a 2-Post ramp I bought many years ago, used several huge capacitors and a 6 inch nail as a plunger with what looked like a coat hanger for a field coil(?) , it did work, but I didn't need it, someone did buy it off me though Andy Quote Link to comment Share on other sites More sharing options...
Warthog Posted August 6, 2006 Share Posted August 6, 2006 Check Ebay..........There are usaully some 2nd hand units on there. Check out: http://www.powercapacitors.co.uk/transwave.htm A good source of info and may just save you buying a Machine Mart special that is not up to the job........? Quote Link to comment Share on other sites More sharing options...
B reg 90 Posted August 6, 2006 Share Posted August 6, 2006 My brother has a phase converter on a 3 phase piller drill. But you do not get the torque out of the motor that you should...... Not the best solution. We have found that putting a replacement single phase motor on is the best. You can get good secondhand 3HP motors for less than £100. Alternatively my dad has a couple of 3 phase dehumidifiers that he is running off single phase. Not sure of the power rating, but apparently all you do is connect 2 phases to the single phase motor, then off one of the wires you put a spur of wire to a slave motor and back to the 3rd phase. The motor resistance apparently alters the phase of the tee'd off wire so that the equipment you want to run sees 3 phase. However most electricians don't know how to do this. There is a description of how to set this up on the internet some where....... It is also a bit of a bitch to start. It has a box with 2 start buttons. You need to press them one after the other with the correct delay or the fuse goes........ Also makes all the lights in the house flicker when you start it... Adrian Quote Link to comment Share on other sites More sharing options...
Mark Posted August 6, 2006 Share Posted August 6, 2006 I am running my milling machine at home with a 3 -phase motor off an inverter - nb, not a phase converter. The inverter was about £150 second hand, and allows me to constantly vary the speed of the 3-phase motor, which is a far better solution than buying a singlephase motor of sufficient horse power to run my mill. The inverter came from a chap who advertises here quite often (not a trader, but mor of a sideline for hime). He was very helpful, and told me what sort of thing I needed, and also helped me set it up. Simonr is also runnig his mill from some form of inverter.. What are you trying to run off it? What sort of power? IMHO this is a much better solution that converting to a single phase motor. Oh, and here is a gratuiitous picture of my mill to show you what I am running... Cheers Mark Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted August 6, 2006 Share Posted August 6, 2006 Good Grief Far too tidy - you should be ashamed of yourself. Let me in there for a few minutes, soon have it a shambles and H&S nightmare Nige Quote Link to comment Share on other sites More sharing options...
MogLite Posted August 7, 2006 Share Posted August 7, 2006 What - ya planning ? Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted August 7, 2006 Author Share Posted August 7, 2006 What - ya planning ? Well I say I done gone bought me a lathe, boy! Nothing Mahoosive, but it is 3 phase. Thanks for the help chaps - I'm investigating the options... Al. Quote Link to comment Share on other sites More sharing options...
MogLite Posted August 7, 2006 Share Posted August 7, 2006 Well I say I done gone bought me a lathe, boy!Nothing Mahoosive, but it is 3 phase. Thanks for the help chaps - I'm investigating the options... Al. Brilliant - I need a lathe Got any tooling with it - I need to know what projects to plan Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted August 7, 2006 Author Share Posted August 7, 2006 Brilliant - I need a lathe Got any tooling with it - I need to know what projects to plan Oh good - I like my stuff to earn it's keep! Re: tooling - don't let that stop you! I seem to be collecting tools at the mo... Might give tube notching a whirl on it too - got the cutters for it! B) Al. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted August 7, 2006 Share Posted August 7, 2006 Sounds like some interesting solutions here You can convert single phase to 3-phase as has been said, but then you hit the limits of your single phase supply - really you'd need to add a direct feed from the fuse box and have a converter that's more than up to the job. Remember electric motors take a huge current at startup. The three-phase motor with another motor then connect to single phase sounds like a horrific electrical bodge, I guess the single phase motor alters the power factor sufficiently to make the 3-phase one run. Far easier IMHO is to fit the best single-phase motor you can find. Wikipedia: Power Factor / Power Factor Correction this will make Al happy, it has maths in it Quote Link to comment Share on other sites More sharing options...
Mark Posted August 7, 2006 Share Posted August 7, 2006 Sounds like some interesting solutions here You can convert single phase to 3-phase as has been said, but then you hit the limits of your single phase supply - really you'd need to add a direct feed from the fuse box and have a converter that's more than up to the job. Remember electric motors take a huge current at startup. John You are of course right. I use my inverter with the speed turned right down to start, and gradually increase the speed untill it is where it needs to be. This should reduce the initial spike that happens when you start the motor. The current draw on my 1.5kW inverter (running a 3kW motor not recommended) is about 3A at the absolute most! Nige, It's not that tidy at the moment - The picture was taken just after I moved the mill in, so everything was tidied in order to fit it thorugh the door! Cheers Mark Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted August 7, 2006 Share Posted August 7, 2006 Mark - how are you measuring that? Power factors are strange things involving complex numbers, the current is at a different angle to the voltage so what registers as a 3A load may be something else in reality. I did this a long time ago so can't remember the exact maths of it all, but in short you can put some huge and unpleasant loads on things without realising. A lot of industrial applications use power factor correction kit to reduce their impact on the national grid (and hence their leccy bill) because of the huge currents drawn (and generated) by leccy motors. Quote Link to comment Share on other sites More sharing options...
Mark Posted August 7, 2006 Share Posted August 7, 2006 Mostly I am using the read out on the front of the inverter to tell me what it's current draw is. Whilst simplistic (and therefore probably wrong) I have also run the inverter and motor combination with a simple analogue ammeter inline with the supply. The two readings were pretty much in sync. I would have thought that the read out on the front of the inverter was designed for specifically this usage in mind?? Whilst the inverter is not current generation, it is not that old, and is a Micro controller affair so may well have a dgree of power factor conversion built in. (If anyone is interested, it is a Hitachi J100). Anyway, it works, it dosn't get hot, or blow fuses. Cheers Mark Quote Link to comment Share on other sites More sharing options...
pugwash Posted August 7, 2006 Share Posted August 7, 2006 wow you're doing well there mark. The current draw on my 2.5kw 3ph motor at 85% load is 12amps! This runs an industrial ventilation unit to pull air over our frying range- impressive bit of kit mind- changes the air in the shop every 45 seconds, creates its own windforce, and has an exit velocity from a 12" pipe of about 65mph! the most the breaker can take is 12.2 amps to protect the wiring so it sometimes trips out- which shuts the shop down! no idea how you're getting 3amps from 3kw but i'd love to konw- i spend a fortune on electricity! Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted August 7, 2006 Share Posted August 7, 2006 3A @ 250v = 750W so something's lying. Quote Link to comment Share on other sites More sharing options...
Mark Posted August 7, 2006 Share Posted August 7, 2006 Probably just the fact that I am running what is essentially a very small machine with a flat belt drive, and that there really is no load going on whatsoever. Even when I start to take what I consider to be a heavy cut it isn't working the motor or the machine hard at all. If I were to try an run an air compressor of something that was actually stressing the motor the story would be quite different I suspect! Mark Quote Link to comment Share on other sites More sharing options...
pugwash Posted August 7, 2006 Share Posted August 7, 2006 yeah that sounds more like it. i was little surprised to find out that the speed on my motor was almost totally unrelated to the curent it draws! the only thing that mattered was the amount of air it drew. i found it interesting anyway! Quote Link to comment Share on other sites More sharing options...
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