To 3 Phase or not to 3 Phase?

[firewood]

has anyone got any idea of the costs of operating equipment powered via a 3 phase supply rather than being PTO driven?

 

 

I know the costs of getting a 3 phase supply installed are often exhorbitant but what about using a diesel generator to supply the current?

 

 

currently Machinemart are offering a 17kva diesel genny for £4160 exc. VAT

 

see here: Clarke Heavy Duty Diesel Powered Generator 3-phase - TX3/ES3 - Machine Mart.

 

 

I know a tractor can be used for other things but if you want a fixed setup in a barn without fumes and excessive noise inside the building it must be an option.

 

I suppose the nub of the question is which is more fuel / cost efficient: a tractor driven pto, a diesel genny or a 3 phase grid supply?

[Mr Ed]

3 phase grid supply is by far the cheapest, but as you say, its the cost of installation.

I would buy some LONG hydraulic hoses before I invested in a 3 phase generator though. Put a power pack outside in a soundproof box, and run your hydraulic power into the buuilding.

[Al Smith]

If do a "Google" on rotary phase converters ,they are not that hard to make .I suppose I've made around 20 or 30 of them .One was a 30 HP unit .

 

They run at around 92 percent efficiency .Most people erronious think you are paying for running two motors to get the power out of one but that is not the case at all .

 

I have to be off to work now but I'll post a pic after I get home .Remember there is 6 Hrs diff in time .

[David Riding]

3 phase grid supply is by far the cheapest, but as you say, its the cost of installation.

I would buy some LONG hydraulic hoses before I invested in a 3 phase generator though. Put a power pack outside in a soundproof box, and run your hydraulic power into the buuilding.

 

 

can you not get 240 to 3 phase converters or do they not have the umpth or amps!

[Mr Ed]

can you not get 240 to 3 phase converters or do they not have the umpth or amps!

Yup. I'm waiting for Al to come back, as he's the expert on it.

[Dave Harries]

You can get 240v to 3 phase variable speed motor drives, I work with them quite allot at work. They aren't that cheap as you have to also include a filter unit and a HIM (human interface module). At work we generally used Allen Bradley drives (Rockwell Automation).

[renewablejohn]

I bought a 3 cyl Lister lighting tower which had a 3 phase 17.5kw generator supplying the lights at 110v and then had it converted to run 3 phase with option of 1 phase to power a demonstration 3 phase pellet press

[AdamnRalph]

You could get a tractor and a 3 phase pto generator youve got the best of both worlds then. 3 phase pto generators come up for sale on ebay quite often. My mate runs his yard off one. I bought a 20 kva one a year ago for 600 quid.

[gensetsteve]

make sure you have plenty of single phase coming in before getting a phase converter. Power it direct with hyd pump if you can. The lister flat top engine was one of the best most durable engines made. The price looks ok. check out Myrak Generators & Construction Plant for prices. Dont buy lister alpha engine, lombardini, ruggerini or anything chinese.

[Al Smith]

Well first of all I have no idea what voltage you folks use on that side of the Atlantic .I've worked on some stuff that was 208/365 Wye from Italy .

 

In the US the supply to most residences is 120/240 single phase .Most modern homes have a 200 amp service ,a few older ones may be 100 amp .

 

To size a rotary you need at least to be the size of the largest motor you will be running .In other words a 10 HP converter will start a 10 HP motor but it will run up to 3 times that amount as long as none are larger than 10 HP .

 

Rule of thumb on 3 phase motors is 2.5 amps per HP running fully loaded on 240 volts .

 

Now here is the kicker .The rotary because it does not produce any usable mechanical work will only draw about 10 or so amps .All it does is generate the third phase through induction of the other windings of the motor .

 

It's really simple if you have a good knowledge of electricity which by the way works the same in the US as it does in China ,England ,Japan or Antartica for that matter .

 

Now I don't know what if any restrictions are imposed on you folks are far as using one of these things or not .We over here can pretty much do as we please .It gets confusing after hearing all the stipulations that you all might be under that we over here are not .They could be wives tales for that matter and me be ignorant of same I wouldn't know the difference .

 

Pictures are of the last one I built which is now running a 10 HP punch press at 150 miles north of me in Michagan

Edited September 29, 2009 by Al Smith