Phase Converters on the cheap would be nice.

It's American, but will probably help....

Charles

I can do a schematic of the converter i just built, no doubt some bright spark[meant] will point out 'you don't want to do it like that'. It happily runs a type30 IR compressor[5hp], mill, lathe, grinder and polisher, not all at once but i can't use them all at once anyway. I used a custom wound transformer, a site transformer could be found cheaper, but i couldn't get one[or matching ones] of decent rating hence the new trasformer. With the trans and caps i think it coast around 200 quid, certainly less than a comercial one and probably less than replacing the main motors - ignoring table and pump motors.

-- richard

Richard you may have posted this earlier but 1) where did you get your transformer and 2) What specs or performance did you have on the type of transformer.

I supplier up here said they are not standard auto transformers 240 up to

415 but a bit more about them.

-- Cheers Adrian.

Adrian,

What I have done in the past is to use a 240 - 240 isolating transformer that has 120 volt tappings on each winding wired as an auto-transformer.

Connect all windings in series (observe phase) so that you have four 120 volt sections in series. Feed your mains live and neutral in across the two

120v sections is the middle, and take your 440 off the extreme ends.

(you may need to unpeel a few turns to get the correct voltage or if there are 100/110/120 tappings you can fiddle with those)

This is the way the windings are connected in a Transwave converter, and I confess to having made two direct cribs in the 15 hp sort of range, one for a vast compressor, the other for a Moog Hydropoint NC machine both long disposed of.

I think Tim Leech is still using one of them ??

Remember an excess of electrons passing through you totally spoils your day so take care.

Andrew Mawson Bromley, Kent, UK

'fraid so! (with a 10hp 6-pole idler motor)

Cheers Tim

Tim Leech Dutton Dry-Dock

Traditional & Modern canal craft repairs

phil There are some articles over at hoolbrooklathes (yahoogroups) and an offer to have a rotary converter made for you. Might be worth a visit Cheers Dave Incredibilium Celeritatem, Vigilantiam, Industriam

Dear all, many thanks for the input on the less than a £1000 converter, I have looked at the links and will now read and digest, it has occurred to me that I know a man who does, for a motor rewind and transformer workshop. A grovelling visit is in prospect. Oh Richard, where I come from it's normal to have more than two arms so we generally run a few machines at once! This brings me to my final Inquiry on this matter. I have two

3ph woodworking machines and will probably end up with a total of five 415v machines for my own use. Using one machine at a time I could provide power via a common socket for each machine but copper wire is cheap to me so would It be worth my while to Install a 3ph circuit and associated breakers? What does one do; lug the converter to the next machine on a trolley? I could easily afford two units at the costs talked about but Is It possible that it would be cheaper to rate a single unit for the most powerful machine then wire the workplace as a 3ph shop? As I stated above, copper and trunking Is cheap and my time to me is cheap. Thanks again for the Input. Regards, Ian.

In article , phil writes

I think that the Transwave products are reasonably priced.

I've just built a simple version with 15hp 3ph motor, excited and run from one phase. This generates 3 phases at 400V, 380V and 380V (no load). Although unbalanced, this runs my Colchester Student fine. Other friends use similar converters with up to 25hp idler motors. No transformer needed.

I determined my Red/Blue/Yellow phasing so that the 400V phase operated the lathe's contactor coil...there has to be enough voltage to do this. The 380v phase didn't seem to be enough.

Having scrounged an old motor, I bought 2 contactors (240v coil) off e- bay, 70uF of motor start capacitors, a couple of switches and a case to house it in. The cost was about 40 pounds.

Apparently using an old motor is OK, even one with sad bearings because there is no side load on the motor. Mine is a 3000rpm motor, but slower speed motors may be better...they get up to speed a bit quicker (?) and draw the transient high starting current for less time.

I feed this unit off a 6mm cooker cable on 30A spur.

Craig Powers

------------------------------------------------------------------------------- Craig Powers snipped-for-privacy@real-time-sys.demon.co.uk

-------------------------------------------------------------------------------

I have my converter wall mounted, and connected by conduit to plugs round the shop.

My larger motors have capacitors fitted so I don't need to adjust the converter for different loads.

-- Jonathan

Barnes's theorem; for every foolproof device there is a fool greater than the proof.

To reply remove AT

I do exactly the same.

However, I have the 415V 3-phase supply from my home-built rotary converter piped round to 5-pin 16A sockets. The reason for this is that I also have 240V variable frequency 3-phase piped round to 4-pin sockets

- so that you cannot plug the 240V machines into the 415V supply! The

415V supply is used mainly for the grinders and older machines where the motors cannot easily be reconfigured to delta. The 240V variable frequency supply is used for the mill and lathes where the variable frequency is useful.

J>