CNC and phase converters

[Aldoseri]

Hi Tool Man,

Is there a way to convert between electrical standards? OK.. Rephrasing. In my country we use 230 volts single phase (3 wires) UK Standards, what i need to do is convert it to 230 Volts US standards (4 wires) is this possible? why? US made controller that work with US standards only.

Thanks

Arif

[Al_The_Man]

Originally Posted by Aldoseri Hi Tool Man, 230 volts single phase (3 wires) UK Standards, what i need to do is convert it to 230 Volts US standards (4 wires) is this possible? why?

The post so far has been on the use of 240v single phase (2 wire) and convert to 3 phase (3 wire).
For domestic use, USA & Canada use 240vac single phase centre tapped for 120vac 1Ø.
The above posts refer to using a 3phase motor running off of single phase to produce 3 phase output.
What are the US 230v 4wire you referring to?
Or are you refering to 3 phase star connected supply with neutral star connection?
Al.

[tool_man]

Not sure where that 4th.wire is coming from Aldoseri.Read the post from Al_the_man.The only thing I can think of is for grounding the motor frame and converter.Always a good practice.

[Aldoseri]

Sorry guys maby i confused you but the information is taken fron candcnc website at http://www.candcnc.com for the ACM 100 power module. they made it clear "No sales to European countries" so i figured it be because of power requirements. Please have a look at the product manual(Sorry can't upload - more than the allowed 500k). I'm also confused, I studied Electronics in the states and have never heared of 230 volts before. as of center tapped transformers, they are available in the local market so no problem with that.

Thanks

[Al_The_Man]

I am still not sure what you mean by conversion as the unit shown will operate on 120 ~230 single phase, two wires and ground, they will in all probability have a tolerance of 220~240 also.
It looks like they restrict sales to Europe because of export restrictions on electronic devices.
It looks like a glorified E-stop relay, I would think it would be easy to put something together using descrete devices.
Alternatively, there are commercial devices on eBay, look for 'Safety Relays' these will perform similar operations if you need this.
Al.

[Aldoseri]

Thanks Al,

Mabe it is a glorified E-stop relay after all.

[TridentMarine]

Originally Posted by Al_The_Man This is a 7HP convertor I made up for running a couple of 3phase mills, it can also be fed into a machine with VFD. I based my design on the articles by Fitch Williams in the Metalworking.com drop box under the 1998 retired files they are JPG files FRW-1 to 7. And with communication with him over tuning etc. I elected to go with a totally 240vac control circuit to avoid transformers etc. A 4pole motor is recommended over a 2 pole, although either will work, the cap sizes will be different. Also it is important that caps Cs,Cp & Pf are AC motor start rated, Cstart can be intermitently rated. I used various 10µfd & 20µfd in parallel during the tuning process. The start button is pushed only long enough for the motor to come up to a good speed, usually barely a second. If any one is interested in persuing this I can dig up the original communication tuning notes. Al

as you offerd to dig out the original communication tuning note , i would like please to help me in this matter i have a single phase service to my workshop and would like to run my three phase lathe machine, 3hp 3phase motor , and i would like to be able to have a well balanced three phase output from my rotery converter... circuit diagrams is very much appreciated...

[Al_The_Man]

The schematic is in the PDF in post #6 also for tuning and other details see all the FRW- posts in the 1998 metalworking drop box. http://metalworking.com/dropbox/_1998_retired_files/
To tune it requires a clamp on ammeter and a AC voltmeter
Al.

[Willbird]

I find the statement amusing that "static converters should have never been invented"

My Dad ran a shop of 3 employees with a good half dozen 3 phase machines on phase converters we built, using a grainger relay, grainger start caps, and grainger run caps. The machines all worked fine, and the amp load on the 3 legs was equal. These are so simple to build, and the same circuit will allow a rotary to self start, I groan every time I see where somebody has bulit a recoil starter or a single phase kicker motor to start the 3 phase motory in a rotary, when it is SO simple to do it that way I stated above.

Dad sold a LOT of these converters around Toledo, OH under the name "B&D Sales" there had been an older guy called "Withey" that sold them but he died, leaving everybody without a source for one....the only problem children with these converts was air compressors, and they just got a bit more start cap and they also worked just fine. He only sold rotaries to people that HAD to have instant reverse.

Power tapping on a bport with one can be done, but you have to brake, wait for the relay to clunk 3 times, then reverse. But as I said 3 guys used them 40 hours a week no problem.........at this time you could buy comercially a static converter, only problem with the commercial one ?? It didnt WORK :-).

I'm told the start/run cap converter with a relay (emf sensing) to shut off the start caps was/is used on refrigeration equipment and the guys that work on that stuff all recognise the setup right off.

Lots and lots of 3 phase stuff out there uses 1-2 HP motors that never reverse, a rotary is overkill for that, the types I mention work just fine, and some guys would start 1 machine then run others in essance having a rotary.

these sold for $75 or so in 1980 for a 1 horse as I recall, I still got calls from people looking for them 10-15 years after dad died in 1986, built a few here and there myself, I have 2 bridgeports running on them now, the one has been running for more than 30 years.... tthat one has the "Withey" that started it all :-)...I think we totally rebuilt it once in that time The other one has been running 20 years.

I'll probably go with a VFD for the bport I'm converting to cnc, and a 3400 rpm 3 phase motor...was looking in Grainger today.

Bill