Wiring a single to 3-phase inverter.

[mickeyw]

MickeyW: I happen to have a single phase to three phase inverter sat in my airing cupboard at the moment. I may be persuaded to part with it (240v, 1.5kW I think). I also have a 3ph to 3ph inverter if it is of any use to anyone.

James - This could be of interest to me. Is your rated KW the amount the unit consumes at 240v or the size of 3-PH motor it can power? If I understand it right, 1.5KW equates to 2HP. What sort of £ would you be looking for?

[TheRecklessEngineer]

The kW rating is constant between the 240v and the 3 phase output - so a 1.5kW 3 phase motor will pull a maximum of 1.5kw from the single phase supply (near enough).

PM sent.

[integerspin]

I will probably go down the smoothstepper route, I was going to try the CNCbrain, there is one

functioning in the wild in Horsham, but they seem a bad bet. I have thought about the dynomotion

Kflop, but it's around $500. Any problems with the smoothstepper.

I will be using granite devices drives, they seem to be pretty good. Annoying thing is I arranged

a good price in sept 2008 and he wouldn't take my money as the new drives wouldn't be shipped for a

week or so and the the pound fell from 1.55euro to 1.05!

So I have been putting off buying the drives, not all bad though as they will be selling a

motion control that uses an RS485 adapter soon, I think. A real killer is the 22% Finish VAT.

Phase converters:

These can be as simple as an old three phase motor spin started and mains whacked across two phases, you can

run a motor from this. Use a piece of string wrapped around the shaft/pulley to get it spinning and switch the

power to it when it's spinning. If the motor was wired to another, thru a switch, you can switch the motor on once

the first has accelerated up to speed.

The next step on from that is to use a motor to spin the generator motor up to speed,

I have seen pics of 50hp motors that were running a couple of VMC's.

Next. Add some capacitors between two of the phases of a three phase motor and wire the other two, switch it on and

away it goes. Now you can either use that for whatever it is, drill, lubrication pump etc or call it a rotary

converter and wire stuff up to it.

I say lubrication pump as I have a Showa oil pump on my mill, with a tiny little three phase motor on it. I looked

at it, looked in the junk[garage] and came up with a capacitor from a microwave oven. I wacked the capacitor

on the motor and switched it on . It works great.

If you add a few more bit's to your rotary converter it becomes a press button and you have 3phase device. Add a

transformer so you have ~420 V and you can just plug stuff in as it came and it all works.

My converter has a 7.5kva continous transformer and it cost less than £200 to build, that's all new componets

including a custom wound transformer. I switch it on and everything works.

It doesn't mind you whacking the mill or lathe in reverse when tapping.

If you want to run loads of stuff rotarys are pretty good, not that I would say no to an inverter on everything.

I also have a 3ph to 3ph inverter if it is of any use to anyone.

How big is it I may be interested, what inverter is it. I can run them from my rotary converter.

[simonr]

I will probably go down the smoothstepper route, I was going to try the CNCbrain, there is one

functioning in the wild in Horsham, but they seem a bad bet. I have thought about the dynomotion

Kflop, but it's around $500. Any problems with the smoothstepper.

Sorry this is a bit off topic! I wouldn't let it all worry you - although it sounds a bit Greek at the moment, soon you'll be speaking the same lingo! As I mentioned before, Mach3 is just like MegaSquirt for Machine tools, a DIY CNC controller.

The biggest problem with Smoothsteppers is getting hold of them!

The Dugong drives are made in Hungary - and he offers free shipping. Since we are both EU VAT Registered, the VAT isn't an issue for me. I decided on them because my Servo motors run at about 120v - and low cost 120v drives are few and far between.

CNCBrain looks great on paper - but they don't seem to have made it in to production properly.

I kooked at KFlop and USBCNC - but both seem to have their own problems. KFlop is trying to be a replacement for Mach - but the software looks a bit 'clunky' to me. In just about every thread about motion controllers - the overall conclusion is that Smoothstepper is better. It's tightly integrated with Mach3 - and it's only $150!

Si