Phase convertor

[Phartsmellar]

Called My Local power company, They said 3 Phase power was not available yet in my area, The Guy on The phone said he had customers who used something called a phase convertor. Anyone Have any Experience with these? I would Like to be able Buy Some CNC Shop Equipment, and an AC system that runs on 3 Phase. He said he had a couple people using something called addaphase? Would like to hear of any 1st hand accounts, Thanks a bunch.

 

[Diablo]

I wouldent even bother with a phase convertor, go straight to a VFD(variable frequency drive) i work on them almost daily and they are gonna be right up your alley. theres tons of info on the net and on here.

 

[Norcal]

One place is to post a question about phase converters is at the Practical Machinist site, as said above though a VFD is a good choice also.



http://www.practicalmachinist.com/vb/transformers-phase-converters-vfd/

 

[rsanter]

I used to use a phase converter
switched over to a VFD and that was the best thing I did
machine ran better and I gained variable speed

bob

 

[Steve from Socal]

For many CNC machines you will need three phase and inverters are not suitable for multiple motor loads. The only phase converter I am aware of that works for some of the higher level CNC machines is Phase Perfect. They are very expensive but, if you need clean three phase power it is your best option.

Steve

 

[ddrewyor]

There are many ways to skin a cat (sorry PETA people). To run a 3 phase machine off single phase I have done it several ways for different reasons. On my Southbend Fourteen 5hp lathe I have a static phase converter ? Phasematic is the brand. I picked a couple up cheap at a garage sale ($40) and they work well. The drawback of a static is that it only provides two of the three phases so you get 2/3rds of the rated hp of the motor and hard starting loads like compressors may not work well. The second Phasematic converter that I picked up I converted to a rotary converter. This required a second 3 phase motor to generate the third leg of the 3 phase. I had it on my compressor and it works well, but balancing the line with the correct capacitors was an interesting process because I did not have a bunch of capacitors to play with. Also, it has to run continuously waiting for the compressor to call for juice. So for my application it was not ideal unless I had set it up to kick on prior to the compressor starting and then shutting off when the compressor kicked off. This is possible with some ladder logic and a simple timer. I just recently picked up a single phase 5hp motor off eBay that I am swapping in. I will keep the rotary for when I get another piece of equipment. We put a VFD on my friends table saw because he found one at an auction and thought it was cool. It's the cat's *** for a single motor device. It has a soft start feature and variable speed control built in. Nice device ? but they can be expensive and sometimes you can hear a high pitched whine coming from the unit. I can hear it but my friend cannot. Also, when looking at VFD's with single phase in the hp capacity is reduced. To accurately match a VFD so you are not over buying you need to look at the wattage of the device and size accordingly. Hp numbers can be deceiving. The Phase Perfect unit mentioned by Steve can supply the cleanest power and I believe are digitally controlled to get you a very high power factor (efficiency) because they are perfectly balanced to the load (remember my comment on the rotary I made). I had no electronics on my equipment (CNC controls) so this was not something I pursued. Ok, Ok ? I would have if I had the money and a good application Maybe next time. It boils down to what you can afford and your application. Good luck

Dave
________
Opiate rehab advice

 

[A_Pmech]

On most CNC machines the only 3-phase loads are the spindle motor, chip conveyor motor and coolant pump. The control is single-phase. Set up the rotary converter to power the control with the two "power company" legs of single phase. The third phase should only be used for the motors. Properly sized to the load and balanced, a rotary should do fine.

 

[nehog]

If you are only occasional use, consider a (surplus) three phase generator set. I got a military surplus one, 15KW (it will do 25 however) and it serves well as a backup generator too... But only useful if you are only using it occasionally, otherwise it will be a PITA...

 

[Steve from Socal]

On most CNC machines the only 3-phase loads are the spindle motor, chip conveyor motor and coolant pump. The control is single-phase. Set up the rotary converter to power the control with the two "power company" legs of single phase. The third phase should only be used for the motors. Properly sized to the load and balanced, a rotary should do fine.

The problem with the rotary with many CNC machines is, the dynamic braking requires a true "B" phase to dump current.

You really have to consider the machines in question to make an informed choice. Any manual machinery and "some" CNC equipment would work fine with a rotary. There is at least one exception to the manual machines. Late Monarch solid state drives also need a Phase Perfect or utility 3 phase power.

Steve

 

[A_Pmech]

The problem with the rotary with many CNC machines is, the dynamic braking requires a true "B" phase to dump current.

You really have to consider the machines in question to make an informed choice. Any manual machinery and "some" CNC equipment would work fine with a rotary. There is at least one exception to the manual machines. Late Monarch solid state drives also need a Phase Perfect or utility 3 phase power.

Steve

Good point on the regenerative drives, Steve. I was thinking more of drives with dynamic braking resistor grids. That's certainly something to look for - a machine with dynamic braking as opposed to regenerative braking - when searching for a machine to run on a phase converter.

 

[Phartsmellar]

Thanks for the Insight, sounds like I need to stick with Single phase electric and buy tools and such that work with what I have.

 

[HoosierBuddy]

I would disagree with limiting yourself to single phase motors.

I recently purchased a 3-phase Southbend lathe and installed a VFD to control it ($120 box). It works remarkably well and is superior to a single phase setup in that I have speed control now through the VFD as well as the pulley drive and back gears the lathe was already equipped with. This gives me much more control over speeds with slower slows and faster high speeds if needed (within the limits of what the old 3-phase motor can take).

The VFD soft starts the lathe to limit any chance of breaking a belt, automatically slows the lathe for stops or reverses and allows a "jog" feature that is handy for getting the spindle into the proper position for engaging/disengaging the back gear, etc.

The VFD makes the lathe way-better than it was from the factory. You can't use a VFD with a single phase motor. Now...what you'll run into with CNC is anyone's guess until you pick out a machine.

Phil

 

[HemiRambler]

3 Phase is where it's at!!! Don't LIMIT yourself to single phase machines. Once you take the plunge - you won't regret it!!! I run all my stuff on Rotary converters and they have been absolutely trouble free - all made from scrap parts and such for dirt. VFD's are sweet, but none of my manual machines ever required one so I could never justify the cost. YMMV