3 phase to single phase

[big soft moose]

HI Folks

looking for some advice on the best bet for using three phase equipment in the 'shop - I was looking at G&M and they have some serious kit avialable but its nearly all three phase (presumably having come from comercial premises that have gone tits up). In particular i want a big heavy lathe like a graduate or a wadkin, but they also have other decent kit too

so as i understand it the options are either to get a three phase supply fitted, get a converter, or to buy a single phase motor and convert the lathe (or whatever)

what are youre thoughts on this ? has anyone done either and what are the costs like ?

 

[jasonB]

For a single machine get a static converter, if you intend on several then a rotary converter rated for the machine with the largest motor.

The rotarys can be a bit noisy. The statics have the advantage of variable speed.

For either of these to work the machine will have to have been fitted with a "dual valtage 3 phase motor" or if you want to pay a lot more you can get 415V 3 phase output.

Have a look at the following companies

http://www.drivesdirect.co.uk/
http://www.newton-tesla.com/
http://www.boost-energy.com/boost/

Jason

 

[katellwood]

if the motor is dual voltage then the way forward is an inverter, it allows you to vary the speed from zero up to twice the motors RPM plus you can reverse the rotation at the touch of a button, get one with I believe vector control this ensures you get max torque at whatever speed you select. there are lots on Ebay.

 

[wizer]

Sorry to thread hog. But can someone explain why putting a 3 phase supply in is so expensive/prohibitive?

 

[Digit]

Sorry to thread hog. But can someone explain why putting a 3 phase supply in is so expensive/prohibitive?

Depends how far you are from a 3 phase supply.

Roy.

 

[jasonB]

You are likely to have 3 phase running down your road, every third house gets one phase etc.

So depending how long your drive is you will need to dig a trench and duct it for the contractor to dig up the road/footpath and connect you.

Electricity board will have to install a second meter and they are usually not too keen on 3phase in domestic property as there is a small risk of a DIYer getting his phases mixed up and having 415 through their wires or worse!!

Jason

 

[tnimble]

Most of the new build houses over here, in Belgum and I believ in Garmanny and Austria have all a 3 phase connection for quite some years now. Either only one of the phases is connected to the meter and distribution board (more and more uncommon these days) or all phases are divided over the distribution board (the common method over the last decade or so). Switching ont a single phase main circuit breaker and a single phase meter out for a new 3 phase breaker and meter is often if not always gratis.

 

[mark]

I've been through the process of installing a 3-phase supply into my house.
It is not impossible - just a lot of organising and patience needed.
The supply company (i.e. the people that own/maintain the cables/substations etc in your area - mine was Scottish Power) will need to be contacted and an initial site survey carried out. Then you will have to dig the trench they specify and collect/fit the underground conduit ready to pull the 3-phase armoured cable through. The supply company make a connection (they did mine live!) to the nearest 3-phase mains cable and connect the other end to a 3x100A fused mains incoming er...thing. They fill in the holes in the pavement/road. The live feeds are then taken from this to your meter, then out of the meter to a 4-lever On/Off switch (1 neutral and 3 phases). Legally this is the only part of their equipment that a domestic electrician can work on (the on/Off switch) - all the rest is protected by crimped-on anti-tamper wires.
I've then taken 1 of the live phases and the neutral and split this to power my house. All 3 phases plus the neutral then go to a 3-phase isolator or incomer depending on your arrangement.
The meter (and you only need 1 for the electricity bill) is supplied by the service provider - E-on in my case - arranging this is as difficult as getting the initial supply! It is supplied free.
The old domestic supply I upgraded was 1x80A I think so I think I'll be OK with a 3x100A supply.
When calculating the supply you'll need, the supply company will ask about max current drawn/machines intended to be used etc. I found that both machinery comapnies and the supply company themselves were very helpful with an obvious novice like me.
Cost of cutting off old single-phase supply + installing new supply to on/off switch was approx £2000 - renewing my single-phase supply was approx £1200 so I just thought - go for "proper" 3-phase and stop deafening myself with my home-made rotary converter!
If I can be of any help please let me know.
Mark

 

[wizer]

Thanks for that. Not that I require it. But it sounds like putting 3 Phase into my workshop wouldn't be too difficult. i.e short run of drive, workshop at front of house, very close to an electric substation.

Worth considering if you wanted to kit the whole workshop out in 3 phase. Might be cheaper than converting the motors or installing inverters.

 

[mark]

Hi Wizer,
That was my thinking - kit out new workshop in 3-phase from the outset. (Though I do have some 3-phase machinery already). Some savings can be made as 3-phase machines are generally slightly less expensive than single. Plus, you're not tied to 3-phase machinery - single phase machines can be accomodated just by wiring in properly through one of the phases (not the house one!)
Mark

 

[big soft moose]

Thanks for that. Not that I require it. But it sounds like putting 3 Phase into my workshop wouldn't be too difficult. i.e short run of drive, workshop at front of house, very close to an electric substation.

Worth considering if you wanted to kit the whole workshop out in 3 phase. Might be cheaper than converting the motors or installing inverters.

yes - interesting , might well be worth pursuing at work - especially as we are moving to a new 'shop soon (in theory anyway). However at home i'm renting and i cant see the land lord going for installing a 3 phase supply so i'm stuck with either inverters or changing the motor over.

how much would an inverter be likely to be (for the sake of argument lets say for a 1HP graduate lathe ) and would that me more economic than swapping the motor ?

 

[Woody Alan]

http://cgi.ebay.co.uk/IMO-INVERTER-3-TH ... dZViewItem

Have a read of all the info in this link it gives prices and power matching towards the end

Alan

 

[Oryxdesign]

I recently had 3 phase fitted in a domestic property to run the aircon I was getting installed. I forget the exact cost but it was less than a grand. They removed the existing meter and fitted a 3 phase unit, I had to get an electrician on site to connect to the new and existing fuse board as the meter fitter just leaves you with nothing connected.

 

[big soft moose]

I recently had 3 phase fitted in a domestic property to run the aircon I was getting installed. I forget the exact cost but it was less than a grand. They removed the existing meter and fitted a 3 phase unit, I had to get an electrician on site to connect to the new and existing fuse board as the meter fitter just leaves you with nothing connected.

given that i could get a brand new LRE graduate fitted with singlephase for arround 1500 notes ( while original three phase graduates are arround 550- 750 notes from G&M) the cost of whichever route would have to be substantially under a grand to be worth it

 

[9fingers]

This topic almost needs a sticky FAQ!

Motor swapping at first sight seems the easy option but depending on the machine the issues are
1)motor mounting, foot or flange and hole spacing
2) Shaft diameter/keyway detail metric or imperial.
3) overall dimensions

Both can be solved if you are handy in the workshop and have metal working machinery to rebore pulleys and re-cut keyways.

Inverters are easy if you have some basic electrical skills and are prepared to buy 2nd hand on ebay.

£50 ish should buy a 1hp inverter if you are prepared to wait for the right device to come up on ebay. If you want new off the shelf then I can supply you from £125 plus vat as a minimum. Also your motor MUST be a dual voltage type for this price to be valid. There are some very much more expensive models from at least one ebay supplier that will convert from 240 to 415 v and invert to create 3 phase in the one unit. These are not likely to be CE marked but for our home use so what?

Pricewise a second hand motor Vs Secondhand inverter the motor will possibly be a tad cheaper but needs to fit or be modified.

New prices? I think the inverter will be cheaper than a quality made motor.

PM me if you want more info.
HTH

Bob

 

[big soft moose]

http://cgi.ebay.co.uk/IMO-INVERTER-3-THREE-PHASE-CONVERTER-FOR-240V-WORKSHOP_W0QQitemZ390031834347QQihZ026QQcategoryZ152957QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Have a read of all the info in this link it gives prices and power matching towards the end

Alan

cheers alan - reading through that it looks as tho i dont want an inverter at all , just a phase converter - i'm not that bothered about variable speed - and it looks as though fitting an inverter would involve so much faffing about with the machine that i might as well just fit a single phase motor.

phase converter on the other hand would be "plug and play"