Single phase to three phase converter?????

[Bright.Spark]

I recently looked at a job where a customer is turning his garage into a workshop and he wanted me to check the electric was satisfactary. The garage is fed by a 2 core 4mm SWA from the house with an earth pin outside the garage and a 4mm earth going to an rcd board. When the customer showed me what he would be doing I was shocked, he has bought lathes and CNC machines from a warehouse. The machines are all 3 phase and he only has a single phase supply. He seems to think you can buy a converter which you plug in and it converts single phase to three phase????? has anyone come across this before?

Secondly the machines are 7.5 horse power would a 4mm be capable of this load? Im tempted to put in a 6mm as he says the converter needs 30-40 amps to work?

Any ideas???? Also do lathes draw a high start up current?

Thanks guys.

 

[Deleted member 26818]

Yes you can get single to 3phase converters.
They do rotary types and solid state types.
Do a google search.
As for the power requirements, you'll have to look at manufacturer's data sheets.
The 4mm² SWA may be adequate, if using only one machine at a time.

 

[Knobhead]

One machine at a time only. I just hope they’ve got dual voltage motors otherwise your looking at two stage inverters (even more losses). As for lathes there’re normally DOL, but with the inverter you can set a ramp up. If he’s bought all this gear he should be able to afford a 10mm 3 core SWA feed. But the inverter still limits it to one machine at a time. Unless he’s got very deep pockets.
Rotary converters are a bit pre-historic and not efficient.

 

[Deleted member 26818]

Who you calling pre-historic?

 

[Knobhead]

Who you calling pre-historic?

And inefficient.

View attachment 7669

They are old hat in all honesty

 

[Deleted member 19807]

I have just made a rotory converter and it works just fine. i could not find a static one that could provide me with 3p+n (also a bit pricey), however a star wired rotory converter worked fine. i have had to put it on a 40A "D" type so it don't trip on startup, I think mine is a 3Hp motor.

I have put in 10mm as i don't just run the lathe.

CNC kit is very touchy so a good static converter is a must, rotory would be no good for this job.