Single to 3 Phase - Anyone good with electrics ??

[JimM]

I'm planning on buying a 3 phase milling machine and am looking at my options regarding the electrics.

The machine has 4 motors so an inverter is no good, static converter will leave me down on power so I'll be going the rotary converter route. Plenty of info on the net about building the unit but my first issue is uping the 240v to 415v (ish) as the mill motors are not dual voltage.

I have been given an old static converter which I'm hoping will come to the rescue. Ideally I'd just like to use the transformer part of it so that I input 240v single phase and output 415v single phase. Here's a schematic of the converter

http://www.mediafire.com/?sharekey=7e0b64b434e472ded956df2962098fcbe04e75f6e8ebb871

The incoming 240v connects to AC1 & AC2, and I'm thinking that if I simply leave out the wiring that runs to the external condensor (ie box of capacitors) then I should get 415v at R & B. Anyone who knows more about electrics able to confirm this ??

Many Thanks

Jim




If I simply leave out the condensor wiring (ie capacitors)

 

[steve238]

Jim as your garage/workshop is so close to the road have you thought about getting an estimate on having proper 3 phase installed?

I would like to get 3 phase at home but my garage is about 200 feet away from the road so i reckon it would be fairly expensive to run that far.

It would be interesting to know though how much it would cost to have done.

 

[JimM]

Hi Steve

Haven't contacted the leccy board but even though it's a matter of only 10 feet would have thought I'd still be looking at several thousands for them to install 3 phase. Bet there's a standing charge too, but as I'll only be using it the odd half hour here and there it's probably a bit OTT

Plus I sort of like the challenge of building the RPC - although if you hear a loud bang one evening and all the lights in the south of the country go dark you know who to blame t

Cheers

Jim

 

[R Kraft]

You would need to look at the power available in watts, minus conversion losses.
How much power will you need at the higher voltage ?
Robert

 

[JimM]

Think the main motor on the mill is probably about 2HP, the suds and feed motors much smaller - less than 1HP for the both

The static converter is rated at 4KvA

Cheers

Jim

 

[M1CDQ]

it might be worth having a quick check at your leccy meter.My old house had 3 phase. 2 of the phases where just teminated only one of the phases was used also a frinds house is the same. when the electric was first put in they ran all 3 phases but only used 1 phase. so you could be lucky and have all 3 phases run to the house but not connected

 

[92a]

3 phase

My nephew was quoted £1500 in redhill so its not always to dear an option

 

[Wedg1e]

Single-phase in, 3-phase out inverters? My lathe and one of the mills share an inverter that puts out 3-phase at 415v so you can leave the motors wired in Star, rather than having to swap them to Delta with a 240v-out inverter... if you follow me.
One such inverter sold on Fleabay yesterday for £155, I paid rather more for mine. Drives Direct at Notts have a good selection.
My Boxford has a 3-phase suds pump and the inverter runs that and the spindle motor without a problem. I've also had the lathe and the mill running together though I normally have them interlocked so I can use one or the other (after all I only have one pair of hands!).
I wouldn't rule inverters out...

 

[Luke]

As has already been mentioned, it's worth looking at 3ph installation, it's not always as expensive as everyone presumes it will be.

 

[Pete.]

I was under the impression that if you run 3-phase to a domestic you had to pay a monthly charge on each of the three phases.