[conceptmachinin]

Hello, and thanks for looking.

I am going to be moving my small CNC shop and not going to have an option for 3 phase power. I was wanting to find out what converter would be sufficient in powering it without problems? What service would I need at the shop? I'm not an electrician, just a machinist, so I don't know much about it. Thanks for any help.


The machines power specs are as follows:

Haas VF3

14 kVA;
200-250 VAC @ 50A, 3-phase;
50-60 H

Thanks

Jimmy

[Al_The_Man]

You did not say if more than one machine.
But you need a 220 v 100amp 1 phase minimum, if just the one and to allow for other accessories etc.
If you are looking to expand in the future and you are putting a new service go for a 200amp service.
This should offset the chance of brown-outs & voltage drop due to sudden current demands.
Al.

[conceptmachinin]

Al,

thanks for the help. It is just for the one machine, but I will also need to run a air compressor to supply air for the machine. I was wondering, what size of a Phase Perfect I would need for the mill? I may one day put another mill in also, so that is in the picture too.

Thanks again.

Jimmy

[Geof]

......but I will also need to run a air compressor to supply air for the machine.....Jimmy

If you have scanned through various threads you might have seen mention of compressors causing problems to other machines when they kick. It might be worth thinking about a separate unit for the compressor; or get one sized for two machines and when the second machine is installed then move the compressor to its own unit.

Regarding measuring the spindle load as Al suggests taking a reading under cutting conditions may give a value that is below the peak. On Haas machines there is a Parameter (or Setting) called Spindle No Wait.

When this is turned on and the line following the M03/M04 command has a G00 the controller does not wait for the spindle to come to speed it overlaps the spindle acceleration with the rapid move.

This is your peak load when the spindle motor and up to three servos may be drawing 195% of full load. On a VF0 where the machine specs called for a 40mps maximum draw with a biggest single load of 35amps I measured 50amps.

It is possible to turn off Spindle No Wait and it is also possible to set the maximum spindle acceleration lower than 195% but both these work arounds for an inadequate electric supply have an effect on cycle time.

[Al_The_Man]

If you still have the machine connected to 3ph supply, you could take a current reading of the machine with a heavy spindle load to see what the machine typically draws on heavy load and then request a recomendation from phase perfect, of course if you are thinking of expanding then you need an estimated load figure of what you may be looking at in the future.
Also what the compressor draw is.
Al.

[Al_The_Man]

One thing I forgot to mention, if the Haas has any single phase source wired across two phases e.g. control power, servo or other power supply power, make sure these are across the two main 240v 1 phase feeds, that enter and exit the Phase Perfect. These provide two of the phases that are relatively stable compared to the artificial phase by the PP.
Al.

[Geof]

One thing I forgot to mention, if the Haas has any single phase source wired across two phases e.g. control power, servo or other power supply power, make sure these are across the two main 240v 1 phase feeds, that enter and exit the Phase Perfect. These provide two of the phases that are relatively stable compared to the artificial phase by the PP.
Al.

Yes, coolant pump at least 1hp, may be more.

[awright]

In your situation, I'd consider shedding off the locally generated 3-phase line all equipment that does not REQUIRE 3-phase power for proper operation. This, of course, depends upon the function and power demand of each piece of equipment.

Before people react negatively, I fully realize the advantages of 3-phase power over single-phase in such equipment as compressors, especially as the power exceeds about 2 HP and goes into the region where single-phase motors are hard to find and expensive. However, when you are generating your own 3-phase power locally, peak demand becomes a serious limiting factor.

I'd look first at your coolant pump and air compressor to see if it is practical to convert them to single phase power. The start cycle of an air compressor is an especially large instantaneous current draw that would be beneficially removed from the phase converter. It will draw even larger instantaneous current off the single-phase line, but that is much more easily handled by your direct line power feed than by your phase converter. If your compressor is large enough that it requires a 3-phase motor, do you actually require that much air delivery? Can you go with a smaller compressor or even two smaller ones that will cycle at different instants of time, thereby reducing the peak demand and allowing single-phase power?

Just a thought.

awright

[Al_The_Man]

I'd look first at your coolant pump

I think Geof just indicated it was already 1ph

[awright]

Well, Al_The_Man, I didn't and still, in rereading the thread, don't see where there is mention of the air compressor being either 3-phase or single-phase or where there is any mention of the power of the compressor. I do see where Geof seemed to be recommending a "separate unit" for the air compressor, by which I assumed he was referring to a separate phase converter. Frankly, I don't see the economics of buying a phase converter dedicated to an air compressor alone, as opposed to buying a single-phase motor for the compressor unless it is a relatively high powered compressor (above about 2 HP).

Remember in evaluating the power demand of a compressor that the industry has gotten away with rating modest sized compressor motors that draw current equivalent to an honestly rated 2 or 3 HP motor as a "5 HP compressor-rated" motor. In my opinion, this is pure hokum that has evolved as a competitive gambit in compressor marketing. Look at the actual current draw and "LRA" (Locked Rotor Amps) of the motor you are considering. The LRA is the instantaneous current draw when power is first applied to the motor with a stationary rotor. It only lasts only a fraction of a second until the rotor picks up some speed and begins generating back-EMF to reduce the current toward operating current, but it can play havoc with a phase converter or a weak power source.

I am a strong advocate of VFD phase converters for the home shop and have used a 3 HP converter for several machine tools in my home shop for about 30 years. But I'm not sure that the economics work out for running a moderate size compressor alone, as Goef appears to recommend. As far as I see, we never did hear back from Jimmy on the phase or power of his compressor or coolant pump or other accessories. I admit that I have never used a rotary phase converter and have never required 3-phase power for more than a 2 HP motor.

awright