3 phase to single phase

[paul hughes]

Can anyone help, I have aquired a boxford lathe but it is designed to run on 3 phase power supply. Is it possible to buy, or does anyone have one to sell, a converter to switch from three phase to single phase electric? The main drive motor is about 3/4 hp.

[nickhenderson]

Paul,
like most things in life, you get what you pay for. Phase converters are readily available both up and down ie 240 up to 415 or vice-versa. Price wise, new from around £125 upwards depending on spec etc etc.
Sorry but i havent got one you can have, however as said, they are out there.
Nick

[Tony Collins 1073]

Here you go Paul. A new digital Converter for seventy quid + 8 for postage unless you can collect from Nottingham.

Good luck.

http://www.ebay.co.uk/itm/IMO-1HP-240V- ... 4ab49aebcd


NB these I think are the drawings.


OR

A used one of the same make as above going on Ebay.

http://www.ebay.co.uk/itm/IMO-1HP-3-PHA ... 58923f953b


If you need any help on the bidding side PM me. I know the ropes very well.

If you do decide to bid, do not I repeat do not enter an automatic maximum bid figure. It will just help the other idiots to push the price up.

[Andy Boylett]

Paul,
As said below you need an inverter. These units simply use modern electronics to convert a single phase supply to a 3 phase one. However, be very careful when buying a cheap inverter unit. Many of the sellers are very coy and don't mention that most of these units convert 240volt single phase to 240volt three phase. A true 3 phase supply is 440 volts (or 415v in new EU rules) between the phases - voltage measured between any 2 out of the 3 wires. The cheap units are only 240volts.

What does this mean for your machine? Well if your motor is rated as 440v/415v and you use one of the cheap units then it will only run at 240/415 = 58% of the speed that it is supposed to. Also, if there are any other electronics in the unit that needed the 415v then they will likely not work.....a lot of machines have 240volt electronics powered from the 3 phase supply by a connection between 2 phases, which gives the 240volts. With the cheap inverters this 'between phase' voltage is 140volts and usually the electronics will not work. Lots of sellers now also supply 3 phase motors designed for 240volts !!!

BUT, if your machine is rated as 415/240v then you can use a cheap inverter and change the wiring connection to the motor so that it still runs at the correct speed.

I have installed a 3 phase ring main in my garage. It supplies a surface polisher, milling machine, lathe, grinder and power cut off saw. I bought a 5hp inverter and it supplies the ring main.

Cheers, Andy

[Tony Collins 1073]

Paul, Drives Direct in Nottingham are not a twopenny halfpenny firm and the Ebay auction which is from Drives direct Categorically states this converter is ok for a Boxford Myford which is what you have. If you are in any doubt then phone them. They have a considerable website and three phone numbers to contact and it will be in their own interests to put you straight regarding the voltages mentioned by Andy.


Tony

[Barrie King]

Hi Paul, try transwaveconverters.co.uk they attend most model engineering shows and will be at Manchester this w/e

Barrie

[Andy Boylett]

Paul,
Should have said.... Drivesdirect is where I got my inverter too.

If you tell me (or them) what it says on the small plate attached to the drive motor then I can tell you which type of inverter suits your machine. If the motor is dual voltage 415 and 240 (both 3 phase) then there is just a simple wiring change to convert it from 415v to 240v three phase, and so able to use the cheaper inverters.

Cheers, Andy

ps. if you want to run other machines on 3 phase as well I have a spare 5hp inverter, brand new. I bought a really old machine that could only run on the full 415v. This one was £500 and I am about to list it on Ebay at £300. it is the type that prduces 3 phase at 240v.

[paul hughes]

Thanks for all the great imput guys, It gives me something to work on over the weekend.

[Mark Partington 2989]

Paul,
As said below you need an inverter.

Andy, WRONG!! - the one thing he doesn't need is an inverter - when will people learn that an inverter converts DC to AC -ONLY!! Single phase inverters are the usual ones you'll find in caravans OR if you want to run your lathe off a battery then three phase inverters are available.

As said above, he needs a phase convertor.

[Andy Boylett]

Paul,
As said below you need an inverter.

Andy, WRONG!! - the one thing he doesn't need is an inverter - when will people learn that an inverter converts DC to AC -ONLY!! Single phase inverters are the usual ones you'll find in caravans OR if you want to run your lathe off a battery then three phase inverters are available.

As said above, he needs a phase convertor.

I was trying to keep it simple in order to help someone. I said repeaedly in the my text that it needs to be three phase and that the cheaper units convert to 240volt SINGLE PHASE to 240volt THREE PHASE. Also, for those with little knowledge searching on "415v inverter" on Ebay gets you lots of the correct items......
http://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p5197.m570.l1313&_nkw=415+inverter&_sacat=See-All-Categories

If he contacts me or diect drives we wil sort him out with the correct gear. I have my own 240 sigle phase to 415 3 phase set up as a complete ring main in my workshop. Two of the motors on one machine had to be switched from delta to star. I also have a phase regulating circuit for my antique Herbert milling machine as it did not like the slightly lumpy sinewaves it got.

[paul hughes]

now sorted thanks. got a unit from the north modelling expo this afternoon.

[Mark Partington 2989]

Nope, don't be daft Mark, you know I am a Chartered engineer and do know about these. I was trying to keep it simple in order to help someone.

Andy, yes, so you keep telling everyone - however, we know it's not aeronautical, mechanical or structural, now we can include electrical engineer in the list of what you're not.

An electrical engineer would never describe a phase converter as an inverter, and as for trying to keep it simple -all you managed to do was tell someone to buy the wrong thing and link to something different. Now, when you're talking about lethal ac voltages, that's just plain irresponsible and bloody dangerous!!

Mark.

[Andy Boylett]

Glad you are sorted Paul.

[Dave Parry]

Forum Administrator’s Warning

Now I have tried my best not to step in here but you two have left me no chose. You both have a difference of opinion about this issue and I don’t care who is right. Andy you cannot call someone daft and expect then not to be offended and upset as this show signs of trying to belittle someone by persisting you know better, I know you are not like this in person, as I have met you. Your forum manner can be very off putting at times, and I think you need to think before hitting that button. Now on the other hand Mark you are also coming across and being aggressive with your first reply which I think started all this off by shouting WRONG!! This also is a sure sign of getting someone’s back up too, I am sure Paul didn’t want you two, to start a slanging match on his thread, so please put this to bed before I do.

[Andy Boylett]

Sorry boss, I am suitably chastised

[Mark Partington 2989]

Sorry Dave - pm sent

[PHIL ATHERTON 2400]

[bWho's WONG dave have not seen a chinamans reply to the thread ][/b]

[Dave Parry]

nice one Phil well spotted, Now amended.