Everything in the cabinet says 50/60 Hz so frequency probably doesn't matter too much.
3 Phase from Single Phase 120/208
- Thread starter CoolWill
- Start date
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Use an electronic phase convertor, like those from Phase Technologies
They are designed to work with CNC and other robotic type machines.
They are designed to work with CNC and other robotic type machines.
MD Automation
Senior Member
- Location
- Maryland
- Occupation
- Engineer
fyi... there was a thread back in 2021 about this question. And in post #35 of that thread, I used a typical delta to wye step down xfmr to create the 3rd leg from a 208Y/120 service which had only L1, L2 and N.
For those curious, the "trick" in the experiment discussed was you use only the Wye side, nothing was connected to the delta windings. L1/N and L2/N energize their 2 Wye windings, which in turn energize their respective windings on the Delta side. Since all 3 windings on the Delta side are in series, the 3rd Delta winding is also energized and it, in turn, magnetically excites the 3rd (L3/N) winding back over on the Wye side.
To summarize that long thread, the experiment worked, but I would not connect customer equipment to it. The third Wye winding is created via 2 magnetic couplings (wye-> delta and then back again). It adds some distortion to the 3rd leg, and uneven voltages too. Also, always risky to connect the POCO neutral to the X0 of a wye transformer. If things are not perfectly balanced (and they never are), objectionable currents can be created as these 2 mid-points fight to establish ground "zero". As pointed out above, you need to use the Neutral connection - otherwise L1 and L2 is just a single phase sine wave. But I would be unhappy about connecting up the neutral to XO forever.
If the PopeMobile was sinking in a lake (with the Pope inside) and all I had to power up the only available 3 phase drainage pump was this setup, I would absolutely save the Pope with it. But I would not use it otherwise, especially for sensitive customer equipment I might be liable for.
10 hp inverter
Wow! This is interestin My motors like higher voltages because they are from Europe. 230V is fine. I oversized the transformer already. Should I go this way? It's up to you. I'd be interested in hearing what others have to say about it.
forums.mikeholt.com
For those curious, the "trick" in the experiment discussed was you use only the Wye side, nothing was connected to the delta windings. L1/N and L2/N energize their 2 Wye windings, which in turn energize their respective windings on the Delta side. Since all 3 windings on the Delta side are in series, the 3rd Delta winding is also energized and it, in turn, magnetically excites the 3rd (L3/N) winding back over on the Wye side.
To summarize that long thread, the experiment worked, but I would not connect customer equipment to it. The third Wye winding is created via 2 magnetic couplings (wye-> delta and then back again). It adds some distortion to the 3rd leg, and uneven voltages too. Also, always risky to connect the POCO neutral to the X0 of a wye transformer. If things are not perfectly balanced (and they never are), objectionable currents can be created as these 2 mid-points fight to establish ground "zero". As pointed out above, you need to use the Neutral connection - otherwise L1 and L2 is just a single phase sine wave. But I would be unhappy about connecting up the neutral to XO forever.
If the PopeMobile was sinking in a lake (with the Pope inside) and all I had to power up the only available 3 phase drainage pump was this setup, I would absolutely save the Pope with it. But I would not use it otherwise, especially for sensitive customer equipment I might be liable for.
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
Pretty sure that would be a non-issue where you only connected two ungrounded conductors from the POCO. There's no conflict as your derived third ungrounded will change as required. This of course gives you instability in that third ungrounded leg's voltage.
Cheers, Wayne
Here's an update. The machine shop foreman, the plant engineer, and myself have all come together on the plan. It's going to take at least $30k to get proper 3 phase out to that location. No one in the office is going for that. Based on the warnings from the machine vendor, they are not going for any type of VFD or phase converter, whether that may be reasonable or not. The vendor did say that power from a generator would be suitable to them. The machine shop is going to fabricate the unit from parts on-hand. They are going to gear it to run at 62 Hz no-load. They are going to remove the engine from the genset and mount the motor in the original housing.
My part is just as if I were installing this generator at the site. I'm going to pipe to the building, pour the slab and connect the electrical. This is the kind of problem solving I love. You guys can think it is insane, but in Alabama, we get it done.
My part is just as if I were installing this generator at the site. I'm going to pipe to the building, pour the slab and connect the electrical. This is the kind of problem solving I love. You guys can think it is insane, but in Alabama, we get it done.
Dsg319
Senior Member
- Location
- West Virginia
- Occupation
- Wv Master “lectrician”
What about using capacitors with the phase shift? I have a feeling I’ve seen this for small motors from single phase supply but could be crazy
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Because:
Which precludes everything except the unaffordable real 3ph supply.
Dsg319
Senior Member
- Location
- West Virginia
- Occupation
- Wv Master “lectrician”
Got that but I’m saying it is possible for just a basic “dumb” 3phase motor load correct?
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Yes, in a theoretical discussion, as long as the source impedance is low enough to maintain voltage balance.
junkhound
Senior Member
- Location
- Renton, WA
- Occupation
- EE, power electronics specialty
Machine supplier says it (VFD) won't work nor will a phase converter.
I call BS or incompetent supplier.
Who is the supplier and what is the machine PN? Only 3 kVA, my surplus pure sine wave UPS for computers will handle that.
Perhaps the supplier tried a modified trapezoidal waveform vfd that did not work. Or they tried to use a small 5 HP rotary phase converter with insufficient capacitance.
I call BS or incompetent supplier.
Who is the supplier and what is the machine PN? Only 3 kVA, my surplus pure sine wave UPS for computers will handle that.
Perhaps the supplier tried a modified trapezoidal waveform vfd that did not work. Or they tried to use a small 5 HP rotary phase converter with insufficient capacitance.
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
Just curious- how much does this machine cost? If it's over $500k then running a 3-phase supply should be an easy sell.
(Does the supplier know that you're not using a regulated getset, but a shop-built motor-generator lashup?)
Edit- if the whole machine contains control systems and other VFDs, then feeding it from a VFD would be a bad idea. OTOH if the load is so small, I really wonder why it was build for 3-phase at all, even if they mfg knew it was available. (I like the idea of using a 3-phase UPS.)
(Does the supplier know that you're not using a regulated getset, but a shop-built motor-generator lashup?)
Edit- if the whole machine contains control systems and other VFDs, then feeding it from a VFD would be a bad idea. OTOH if the load is so small, I really wonder why it was build for 3-phase at all, even if they mfg knew it was available. (I like the idea of using a 3-phase UPS.)
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
Assumed...... doesn't that make it manufacturer's issue, not the shop's?
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
Not saying I don't love a crazy lashup, but I'd ask the machine vendor how well they do with open delta supplies. Because if they can handle that then the open wye: open delta transformer approach for 3kVA just needs a pair of 2kVA 120:208V transformers and appropriate protection hardware.
I don't know how much it cost. But I wouldn't think it was anywhere near $500k. I don't know the design reasoning. I never even considered the UPS. That's a good idea. I suppose they make them with single phase input and 3 phase output?
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
That would be an electronic phase converter.
Yes, but not the same as the standard "static phase converter." It would be a pure sine wave inverter.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
I never used the word Static. I specifically said Electronic and gave a reference to a manufacturer.
I suppose that's true. I hear "phase converter" and my mind goes to the two types of phase converters that have been around forever, rotary and static. If your device will put out a sine wave 3 phase 208Y/120, I'll ask them tomorrow if it's acceptable.
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
It appears that the smallest Phase Perfect 18amp/5HP converter (PTS005) comes in under $1500 (it's on their web site, might get a discount just by asking). Is it worth the hassle to build something? I wouldn't think so if this'll do the job.
It sounds just right, now that I'm reading it. It seems like it is just a sine wave inverter powered by AC. I don't know why it wouldn't work. I'll bring it up to them tomorrow.