Author Topic: phase convertor (Read 24187 times)

Andrew Wildman · « **on:** August 16, 2015, 02:51:13 PM »

third project that I completed was my 4kW phase convertor. Originally I had a small static one but with the larger mill it would not cut it. This design wasw based on the info from the workshop practice series 'three phase conversion'.

The step up transformer is a modified cytringan 180A stick welder, that also still serves as my AC stick welder(£30 ebay)

The idler motor is a 4kW unit from ebay (£40). This picture shows it running unloaded, the voltages are better matched with some load:

Gubbins - main contactor, idler thermal trip, driven equipment thermal trip, start capacitors and relay as well as run capacitors:

Works well, runs larger equipment than the static machine does and smaller equipment more smoothly that the old static. At about £120 all in was much cheaper than putting an invertor on all mu machines, although clearly you have no ability to change speed.

rotorhead · « **Reply #1 on:** August 19, 2015, 05:16:29 PM »

Impressive to say the least, I had to go with what's on offer, ready made wise, as I haven't a clue when it comes to electronics...well done...

Auskart · « **Reply #2 on:** August 20, 2015, 02:58:59 AM »

Do you have a circuit diagram for it.

Cheers Shane.

Andrew Wildman · « **Reply #3 on:** August 20, 2015, 07:51:13 AM »

hi shane,
If you are interested in building one it is worth buying the book that I referenced as it gives a lot of other useful info. The circuit diagram can be made up from bits of the book

glumpy · « **Reply #4 on:** August 25, 2015, 10:54:55 PM »

The couple of things that I have that are 3 phase I just set up individually. That way you can fine tune each machine to get the best performance.
It's just some caps that I start off with some ballpark values for and test from there till I get the best start and run.

Clearly you must have some professional electric education to wire something like your converter up. It's a real beauty and so neatly laid out.
I'd be putting a clear cover on the thing and lying I lost the original one just so I could show off my handy work to my mates and -appear- to be humble about it! :0)

DavidA · « **Reply #5 on:** August 30, 2015, 02:28:17 PM »

Andrew,

Very interesting. It may be the way for me to go.

One small point, very small, usually three phase wiring is red, white (or yellow) and blue.
Is there any particular reason you chose black, brown and grey. ?

Just curious.

Dave.

John Rudd · « **Reply #6 on:** August 30, 2015, 02:37:44 PM »

BBG are the European harmonised colours for wiring 3 phase .....

Admittedly I prefer the RYB scheme, much more ~~colorful~~colourful.....

vtsteam · « **Reply #7 on:** August 30, 2015, 08:16:49 PM »

Very nice installation!

rotorhead · « **Reply #8 on:** September 01, 2015, 12:31:05 AM »

Hi Lads,

Bought some 3+E cable from a wholesaler a bit back, the colouring of that cable confused me too as it was Brown, Black, Grey and earth(Green)...

DavidA · « **Reply #9 on:** September 01, 2015, 12:30:27 PM »

Yes, Makes you wonder why there was a need to change from the Red, Yellow and blue.

I'm certain that the old system was easier to differentiate in bad lighting conditions.

Anyway, I've sent for the book and it will probably be placed on the 'things to do' list.

Andrew,

Was there any thing not mentioned in the book that needs to be known ?

Dave.

bertie_bassett · « **Reply #10 on:** September 01, 2015, 05:57:35 PM »

Quote from: rotorhead on September 01, 2015, 12:31:05 AM

Hi Lads,

Bought some 3+E cable from a wholesaler a bit back, the colouring of that cable confused me too as it was Brown, Black, Grey and earth(Green)...

just wait till you get a 5 core (3+N+E) that now got the blue in it for the neutral. connect it up to an older install with old colours ( blue for L3 and black for N) and your in for a right bit of confusion!

Andrew Wildman · « **Reply #11 on:** September 02, 2015, 08:01:29 AM »

Dave, the book is pretty good. Using the welder as the autotransformer was my idea and wiring in the volt meters was also not in the book but the book covers the rest. there is a bit of pulling together various bits that are scattered through the book to suit your installation but it is not too difficult.

DavidA · « **Reply #12 on:** September 02, 2015, 09:54:47 AM »

Andrew,

Thanks. The book should be here in the next couple of days and I am looking forward to planning the project.
I've a pretty good idea of what will be involved (I was an apprentice industrial electrician many years ago, before I switched to Diesel mechanic) and don't see any big problems.

The voltmeters to monitor each phase is a good idea. I may steal it.

Dave.

Andrew Wildman · « **Reply #13 on:** September 02, 2015, 02:30:57 PM »

look forward to seeing your progress. The voltmeters are just ebay cheepos but they are sufficient to ensure that the voltages are fairly balanced and to ensure that you are getting 3 phase.

lordedmond · « **Reply #14 on:** September 02, 2015, 02:38:25 PM »

When I started my apprenticeship TP colours were Red White and Blue neutral was Black earth was Green

a couple of years later White became Yellow

but as has been said the old colours were better in low light and dirty conditions

TRS was mucky Red, mucky Black and evan more mucky Green , get some founder dust on them and a bell set was your friend

personally I do not like the new style TP&N colours

Stuart

DavidA · « **Reply #15 on:** September 02, 2015, 02:59:42 PM »

I understand that one justification for the change was that colour blind people have problems with red and green.

Dave.

lordedmond · « **Reply #16 on:** September 02, 2015, 03:14:24 PM »

Yep one of the electricians I worked with during my time was colour blind on red and green , it was the old TRS cable that he had trouble with especially in the moulding shops

CB is common in males but uncommon in females , my daughter is CB on R and G , but I am ok and there is no history in mine or the wife's family .

To the OP sorry to derail your thread you did a good job on the phase converter , what's the PF like , do the caps provide enough lead to counteract all the inductance in the circuit with two motors running

Stuart

DavidA · « **Reply #17 on:** September 04, 2015, 05:52:35 AM »

Andrew,

The book arrived yesterday and I had a quick scan of the relevant parts.

It appears that the heart of the whole thing is the 240 to 415 Volt auto transformer conversion.
The rest being a normal Steinmetz capacitor arrangement driving an idler motor.
So I don't anticipate too many problems.
I've done a couple of transformer rewinds in the past and found the most difficult part getting the lamination's back in place.
Now need to go have a good look at my old stick welding set.

Dave.

Andrew Wildman · « **Reply #18 on:** September 04, 2015, 07:37:26 AM »

dave,
I did not rewind my welder. I looked specifically for a 240/415 v input version and then just connected 240 in and 415 out (built a little terminal box that sits on the top plate) also means it still works as a welder

DavidA · « **Reply #19 on:** September 04, 2015, 09:26:06 AM »

Andrew,

That's cheating; but a good idea.

I may look around for a dual voltage welder on ebay and sell my present single voltage one.

Lot's of options.

Dave.

John Rudd · « **Reply #20 on:** September 04, 2015, 10:17:08 AM »

Dave
It may be worth considering buying a transformer if you have the money....
Try Drives Direct and ask for Dave..
No affiliation etc.....

DavidA · « **Reply #21 on:** September 04, 2015, 02:05:15 PM »

John R,

Thanks for the tip. I'll do that.

Dave

DavidA · « **Reply #22 on:** September 08, 2015, 09:45:37 AM »

John R,

Successful outcome with Drives Direct. Transformer arrives Thursday.

Thanks again for the tip.

Dave.

Thomas Webb · « **Reply #23 on:** September 12, 2015, 01:36:19 PM »

Hello Andrew, I have a welder it is 440v or 240v (89 and 100v)input Will it be ok to step up on rotary converter?

Andrew Wildman · « **Reply #24 on:** September 13, 2015, 05:09:23 PM »

Thomas, that will probably be a bit high as the voltage I get is higher than the 415 tapping of the transformer if the load is not optimum for the caps that I used. Also will require 500v caps which you may find hgarder to get hold of.

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Author Topic: phase convertor (Read 24187 times)

lordedmond

lordedmond