Converter

[bristol188]

Help please. I would like to build my own 240v AC to 415v 3ph converter (new home no 3ph) I have 15amp 240v available and require 2amps output to start and run a 750Kw (1hp)Max. motor, on lathe, Mill and Drill. I need 3ph for quick rotation reversal for tapping etc. (Without tapping head) I am fully aware of the safety implications and have a good knowledge of using mains power. A circuit diag. would be great Thanks Rog.

 

[RadioRon]

Some woodworkers, those that are good at scrounging motors and such, build converters using an old 3 phase motor. The method is described on page 99 of the "The Workshop Book" by Scott Landis, Taunton Press, 1998 and probably many other woodworkers handbooks as well. While not the most efficient method, it looks pretty simple. While this does not give you the higher voltage, perhaps you can also scrounge a 3 phase transformer to integrate into the system.

 

[bristol188]

Yes thanks for that but I did want a solid state set up. I was wondering how far a TIG welder gets along these lines? Mine is 240v 15amp input maybe I could tap in to the first stages and still keep it's functionality whilst using its case and portability. I should also say I can buy what I am looking for for $2000 Aust but I think I could easily buy the components for half that, what do you think? Rog

 

[Andy1845c]

I am familiar with the set ups with the idler motor as Ron mentioned, and have seen solid state converters, but I honestly have no clue how they work. I'd imagine they are quite complex? I have never run across a circuit for making one online.

Would it be more cost effective to re-motor your machine? Is your lathe, mill and drill an all in one unit?

 

[bristol188]

I am familiar with the set ups with the idler motor as Ron mentioned, and have seen solid state converters, but I honestly have no clue how they work. I'd imagine they are quite complex? I have never run across a circuit for making one online.

Would it be more cost effective to re-motor your machine? Is your lathe, mill and drill an all in one unit?

Hi. No the machines are all separate, but would only be worked one at a time.
And as I said single phase motors will not reverse their direction quickly enough, even although they would be under very small loading.
I have found at circuit for a Rotary Phase Converter that looks OK. It will only run when you switch the machine motor on, which is OK as I thought they had to be switched on and running to use. Thanks for your interest. Rog

 

[Andy1845c]

It will only run when you switch the machine motor on, which is OK as I thought they had to be switched on and running to use. Thanks for your interest. Rog

Just run when the machine is running, or just run to start the machine and then power off?

The rotary motor will have to be up to speed to produce the "3rd phase" to start your tool. I don't think you can start both at the same time. The idler needs a few seconds to start and reach normal speed.

If you shut off the converter after the tool is on you will loose a large percentage of the tools power and the motor will be easy to stall, and if it stalls it will not recover on its own, it will need the converter again. Also, your direction switching will not work.

Normally a rotory phase converter is running as long as the tool is in use.

 

[bristol188]

Yes thanks Andy. I understand what you mean, I will go for running the rotary
motor before I jump on the machine to operate. At first I was not keen on the idea but I think it will be OK. I'll just have a light to tell me not to leave it on when I'm not using it. Rog
I just thought I'd add the light will stop me having to go out to the shed in the middle of the night to shut it off! Ha.