Drill Motor - Am I Missing Something?

[OnOff]

Oooh right!!!Well, it is a bit dark to take a photo now, but i will tomorrow... But first, how to get around the "motor wound in delta" problem..

Now, this took lots of sitting on the bog to work out, and if you choose to do it, you do it at your own risk!!! and, if after reading this you have a hernia laughing, then do not blame me!!!!!

I have seen people say, why don't you use a power tool transfomer the "Wrong way around" Well, it will not work that is why!!! Try it, it will just blow fuses.....

Soooooo... Now, i am NOT an electrician, but i do have a bit of knowledge, so here is what i did...

Take yourself a yellow power tool transformer. Take the sockets off the front. Now, so far as i can remember, i disconnected the earth from the transfomer core and used it to go DIRECT to the converter [the tranny is all plastic so who cares!!]

I cannot remember if i disconnected the CTE bit in the centre of the secondary too, i rather think i did.....[was YEARS ago] Anyway......

Now, what you must do is this; You got your neutral and line feeding the primary, yes?? Now, join one end of the SECONDARY to the line end of the PRIMARY

You now feed your converter neutral from the the neutral that is connected to one end of your PRIMARY and take your line from the other end of the SECONDARY.

What you have done, is you have converted your "ordinary transformer" into an "auto transformer"

Instead of REDUCING the 230/240V to 110V it will now ADD the 110V to the 230/240, so now you have got 340/350V Not perfect, 380 would be nice, but it works!!!!!!!!!!!!!!!!!!!!

If you have the secondary the wrong way around, you will still have 230V just swap the wires around.

If you are barking mad enough to do this, it is up to you!!!! But hey!!!!! Full marks to newbie me for thinking it up eh!!!!!!!!!!!

Next you need an idler motor to make your rotary converter bit. I used a 7.5hp 415V star wound motor from an old miller i had here once.

Tomorrow i will dig the converter out, and take some photos, and tell you what size caps i used!!!

I would make a video of the machines running on it, but i have converted my transformer back to "normal" now!!!

I used it for about a year on my power hacksaw, and a clarkson tool grinder, and i can honestly say that there was NO difference in the running compared to "proper" three phase, [i got three phase now!]

It worked UNBELIEVABLY well, FAR FAR FAR better than single phase motors....

You run a machine with a single phase motor on it, then fit a three phase one, and there is a huge difference in the smoothness it runs, plus all your starters, reversing switches, etc will work properly. I converted a few machines to single phase, worst thing i ever done.... Just cost me an arm and a leg to convert them back.....

here is the motor i used as an idler anyway.. I was fitting new bearings at the time!!

View attachment 4090

john...

Sounds like we both have a similar "disease"............I was just looking in the garage at a 110v trannie thinking about using it "the other way around". Does the idler motor HAVE to be star wound? Can't see your attachment BTW............

 

[apprentice87]

Hi Again,

No, i do not think it makes any difference whatsoever what sort of motor you use as an idler, i just used one i had here. Here it is[ hope it works this time!!!]

View attachment 2921

Tomorrow i will post some photos of the converter itself. I was going to finish it off properly, and mount it all in an enclosure, with volt meters for each phase, but in the end i never got around to it. It still worked ok though!!!

john..

 

[steptoe]

Just found this
https://www.youtube.com/embed/COCffDnJwEQ?feature=oembed

:shakehead

---------- Post Auto-Merged at 01:45 ---------- Previous post was made at 01:42 ----------

that is pure *****!

 

[apprentice87]

Hi all,

Right where was I, Ah, the homemade phase converter!!!

Here we have a photo of the basic thing...

View attachment 2924

As can be seen, the power to the thing is supplied from the modified power tool transformer by means of the yellow plug, no prizes for working that one out.

The output meanwhile, i have divided into two, the power for the idler motor on the left hand side of the connector strip, and the output for whatever you want to run on the right hand side.

You will notice that i have labeled the terminals L1, La, and L3. These are quite arbitary labels, and do not mean much, the eagle eyed amonst you will spot that L1 on the left, is connected to L3 on the right. This does not matter at all, the important thing, is La, this i used as the name for the "artificial" phase.

So basically, you connect neutral from your supply to the L1 terminal, and line to the L3. Now, the second set of terminals are merely in parallel, so you can forget them a minute.

Now, call your middle terminal La as i have said. In between the incoming neutral and La, i connected a 30mf capacitor. In between the incoming line and L3, i have connected two capacitors, but only because i did not have one the right size, so i used a 20 and a 30 in SERIES to give about 14mf

So far so good.

Now you have to arrange for the starting of your idler motor....

To do this, i arranged a 75mf cap, in PARALLEL with the 30mf one in between incoming neutral and our La. You need to fit a switch so you can switch it out of circuit once the motor has started. I used a car "flasher" switch, so it would disconnect when i took my finger off it.

You will also notice a 47K wire wound resistor across the 75mf start cap. This is to discharge the thing once it has done its job, as, otherwise, sometimes when you go to re-start the thing you will have a mighty arc at the switch as the cap discharges!!!

View attachment 2925

Anyway, how do you work the thing???? Plug in the idler motor. Plug in the transformer and switch it on. Press down the flasher switch and switch on the power with the red DP switch on the left, the idler motor will run up to speed only the merest fraction of a second slower than it does on true three phase. As soon as the motor starts, let go of the starter switch. The motor will now run smoothly and quietly.

Plug in the machine you want to run, and just use it normally!!!!

I mainly used it on my hacksaw and a cutter grinder. The phase voltages were all within about 3 volts, which is better than the DNO manage.....

I did once try it on my 5 hp lathe. It struggled to start the thing as there is no clutch, but i still managed to tear off a 1/4 cut from a bit of 3 inch bar!!!.

I was very pleased with it i must say.

For anyone thinking of "converting" a three phase machine....Please do not, it is the biggest mistake you will ever make trust me.... You are far better off making a converter, the machine will be smoother, better, and just, well, great!!!!

If you are interested in this sort of thing, make one!!! You will be so glad you did, and delighted with the finished results...I was!!!!

john...

 

[apprentice87]

Must add mind, that this was only a prototype to test the idea. I was going to make a proper job of it then, but never got round to it, as i got proper three phase power shortly after, so do not think i do all my wiring using car flasher switches, no earthing and bare conductors!!!

john....

 

[steptoe]

Must add mind, that this was only a prototype to test the idea. I was going to make a proper job of it then, but never got round to it, as i got proper three phase power shortly after, so do not think i do all my wiring using car flasher switches, no earthing and bare conductors!!!john....

and the problem is ? what?

Ive seen worse, and still worked,

actually, there are a lot of 5WFW on here would probably think what you done was proper.!