Adapting a 3 phase industrial machine to single phase

[James]

Just what I was going to suggest. It maybe that the overall load precludes this and would blow a 1P 100A fuse. Could also be cost prohibitive.

This is an old thread but I feel I should point out that most 3 have machines are looking for 400v between phases.
by using an inverter from 230v input, you only get 230v between phases and would then need to modify the wiring of all the motors to suit.
also you can have problems with other devices that are expecting a higher voltage.

 

[slartybartfast]

This is an old thread but I feel I should point out that most 3 have machines are looking for 400v between phases.
by using an inverter from 230v input, you only get 230v between phases and would then need to modify the wiring of all the motors to suit.
also you can have problems with other devices that are expecting a higher voltage.

Yes but you can step voltage up easily with AC using a transformer.

 

[Gareth Blackstock]

Hello,
Thanks for the input. James, I initially planned to use the VFD to try and fool the machine's electronics into thinking it was getting the full measure of voltage, I also pulled the fuses on the two motors that were 3 phase. It worked enough for me to see if all parts of the machine were working. I then removed the 3 phase connection and wired in single phase directly. With the 3 phase motors still disconnected, I managed to get the machine running using just single phase. So my next step would either be replacing the 3 phase motors with single phase equivalents, and installing switches to manually control which components run and when. Doing so removes the automated benefits of the machine, but allows me to control the voltage draw by choosing what to run and when.

And also when I installed all fuses and tried to run the machine on the VFD, the VFD reported "under voltage at source"

However, slartybartfast has an interesting suggestion.... if I was to install a step up transformer.... what type? There are quite a few.... Would I install it between the single phase source (powerpoint) and the VFD? Then would I be able to run up to 2 three phase motors as well as the other components?

Cheers, Gareth

 

[slartybartfast]

Hello,
Thanks for the input. James, I initially planned to use the VFD to try and fool the machine's electronics into thinking it was getting the full measure of voltage, I also pulled the fuses on the two motors that were 3 phase. It worked enough for me to see if all parts of the machine were working. I then removed the 3 phase connection and wired in single phase directly. With the 3 phase motors still disconnected, I managed to get the machine running using just single phase. So my next step would either be replacing the 3 phase motors with single phase equivalents, and installing switches to manually control which components run and when. Doing so removes the automated benefits of the machine, but allows me to control the voltage draw by choosing what to run and when.

And also when I installed all fuses and tried to run the machine on the VFD, the VFD reported "under voltage at source"

However, slartybartfast has an interesting suggestion.... if I was to install a step up transformer.... what type? There are quite a few.... Would I install it between the single phase source (powerpoint) and the VFD? Then would I be able to run up to 2 three phase motors as well as the other components?

Cheers, Gareth

Some interesting design decisions to be made. I would suggest that this is not the forum for those as is well out outside of normal electrician territory.

 

[Gareth Blackstock]

Really? The step up transformer question seems well placed in this forum, do you know of a type that could be used before a VFD?

 

[James]

A rotary phase converter is probably your best bet. Much simpler than transformers and vfd.

 

[Gareth Blackstock]

Yeah the rotary converters looked like the best choice from the start, but the cost is too high. This machine is for private use, not within a businesses financial sphere... I have to explore cheaper "work arounds" hence the alternative like single phase connection, remove all 3 phase motors. How hard would it be to wire in a step up transformer to act between house mains supply to VFD to 3 phase machine?

 

[DPG]

Some interesting design decisions to be made. I would suggest that this is not the forum for those as is well out outside of normal electrician territory.

I disagree Mikey - there are members on here with extensive knowledge of this sort of thing.

 

[James]

Honestly, by the time you have installed a vfd and a 3phase step up transformer, you will have got above the cost of a rotary phase converter.

also, your bespoke system may well encounter problems with the unusual issue that a vfd is designed to run a single motor and by design this will have a near perfect power balance across phases.
your machine with single phase loads switching on and off may well trip the vfd into fault.

 

[Gareth Blackstock]

Thanks for the good info guys, it helps me work out how to connect the machine. Mostly i am inclined to simply replace both 3 phase motors with single phase equivelents, and circumvent the 3 phase controller board and re-wire all other 240 volt motors individually.

The machine is an old film processing unit, basically low amp 240volt motors, 2x 240volt pumps, 2x 240volt heater elements....