I am on a domestic supply, 240 volts single phase, and have a 3phase Shaper with a 3HP/2.2kw motor. I know the Fisher & Paykel brand of Washing Machines use a three phase motor for use on a domestic supply. Would pinching the inverter out of one of their machines be an option for me do you think?
I don't know much about electronics, I don't know what the F&P motors are rated at, I am concerned it may not handle the load.
Phase converters and boosters are so expensive to buy.
There is an article in Wikipedia about using a larger 3PH. 5 or 6HP motor and re wiring one of the phases as a generator to run the 3Hp motor, but seemed fraught with problems.
My other option is buying a single phase 3hp motor, but I believe they won't perform nearly as well as a 3 phase motor, hence the three phases.
Would be interested on your thoughts, ideas, any help at all

 

I have not looked at the Wiki article, but I can say from experience that using a 3Ph as a generator is not at all complicated. Basically, all you need to do is get it started turning. Each motor you add to the chain, increases what you can handle. I had that arrangement in my shop for 20+ years with never a problem. Plus, you have the advantage of instant reverse/stop. Single phase does not give instant reverse in most cases.

If you decide to go that route, post back and I will search for my diagrams. I used a simple capacitor start for the generator. John

 

the old sollution of single phase to 3 with a motor/generator set still works.

it's not pretty, will be bigger than an electronic version, but does work

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Thanks guys. Little knowledge is dangerious, turns out the F&P motors while three phase are DC. Jpanhalt if I could take you up on your offer of a diagram that would be really good, Simple is certainly me when it comes to electricity.
I don't need anything flash, just safe and that works. There seems to be plenty of three phase used motors around unlike their single phase counterparts.Thanks again much appreciated.

 

Hi Ruuf,

My converter was built in 1984 using paper plans. Thought I saved them, and probably did inside the box on the converter that is presently in storage about 20 miles away.

Here are a couple of resources:

SINGLE to 3 PHASE CONVERTER

The author, Jim Hanrahan, includes a good description and schematics. Figure 1 shows two run capacitors and a start capacitor. While his design is self-starting, the start capacitor does not automatically disconnect when the converter ("idler motor") gets up to speed. The user has to hold the start button in for that time (it is about 1 to 2 seconds).

One way around that is to use a potential relay, such as are used in HVAC and other installations, on the generated leg of the 3-phase. When the idler is up to correct speed, the voltage in that leg increases, and the potential relay automatically removes the start capacitor from the circuit. My converter works like that. You just turn one switch on, you hear the potential relay click, and you have 3-phase. I would strongly recommend going with the automated disconnect for the start capacitor.

Here is a link to a circuit that uses a potential relay: Phase Converters

We don't know where you are located. Potential relays may be hard to find at consumer outlets. Check with a industrial outlet (such as Grainger) or HVAC supplier.

For my converter, I used a 5HP Baldor 3-phase motor. It was cheap, because the seller got it by mistake. I had a 8"x8" enclosure mounted to the side with a 3-ph socket and on-off switch. The capacitors and relay fit nicely inside. A 3-hp lathe and mill worked fine off of it. I have heard that while the newer motors work as rotary converters, the older, heavy-iron motors work better.

John

 

I have seen three phase motors run from a single phase by connecting 2 phases to line and neutral, and the third phase to a running capacitor. The motor was wound for 230 volts between phases, and the single phase mains was 230 volts.

I guess that it wasn't as effecient as running from 3 phase, and maximum power would probably be less.

 

Thankyou so much for that John, looks good.
Diver3oo, now you mention it, I have two phase in my garage that the previous guy used for his hydraulic hammer, but not being a sparky myself haven't tried it. There is a three phase outlet with "wired for two phase" written in masking tape across the face of it. I asked the electrician about it, one time he was out here, some time ago, and he said something about it using two sides of my switch board. With not knowing how its been set up, I hadn't seriously considered it for three Phase three HP. You think it's worth a shot?
John, I live just out of Rotorua in New Zealand which is in the central North Island, the Bay of Plenty. Probably not a place you guys would like to live, as certain parts are very high in sulphur and very hard on electronics. Appliances fail while still under warranty, computers crash regularly and phones play up all the time in the worst parts of town, not to mention the smell, but the tourist's love it.
Hey thanks again for all your help

 

I have had a few students from New Zealand who shared pictures of home. It is one beautiful place. Maybe someday, I will get to visit.

You will notice the term "idler" used a lot in the discussion of the generator. The idler/generator acts like a flywheel and allows other motors in the chain to start under load. It is quite easy to get a 3PH motor to start using single/two-phase power and a capacitor, if the motor is not under load. When the motor is under load (like a lathe), then you need an idler. I have heard of shops that simply put a sheave on the output shaft of a 3PH motor, wire it with single phase and a capacitor, and then start it with their foot. That, then, allows everything else to run. The self-start designs are basically the same thing, but they use a capacitor instead of your foot to get the shaft of the first motor to rotate.

I believe single phase and two phase are the same thing. The "split panel" probably refers to using a "common" wire like we do in the US to get two 110 circuits from a single 220 circuit. It is usual practice to put one leg of the 220 (say L1) down one side of the service panel and the other leg (L2) down the other side. The common is grounded at the service entrance. Thus, two 110-volt circuits could be off just one side of the panel or split with one off L1 and one off L2.

I need to get to my storage area in the next week. I will hunt for the exact drawing I used and post it, if someone else doesn't post the same thing beforehand. Regards, John

 

Yea, something like twenty three fresh water lakes around Rotorua, and my wife is into sea fishing. Could be a lot nicer, I think a lot of people have been very short sighted. Most of the North Island was once mostly very beautiful native bush, which has been turned into pine forests with no screening, and now much of that is being converted to Dairy. They've removed a lot of bush and let it go to weeds, particularly along the sides of roads, and in my opinion spoilt a lot of the country side views with Power poles which could go underground. The amount of trash on the sides of the road and in our streams and particularly back roads saddens me too. You don't have to travel too far to see big changes in the scenery here though, the sea is about 45 minutes, the ski fields couple of hours at most, Bush walks on our door step. There are even large glaciers on the west coast of the south island, they seem so out of place.

 

Somehow I doubt this is the case in his installation.

New Zealand has the same 230V distribution system as Europe. There are three 230V phases and domestic customers only get one phase and businesses normal get three giving 400V phase-to-phase.

Although it's often called two phase, the 110V system you have in the US isn't a two phase system, it's a split phase system - one phase split down the middle.

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Hi Ruuf, you are in Rotorua?

I build one of those converters years ago and it works well.

I may have even posted the topic here, but as other members said too, same principal.

I use an old Heemaf, Hengelo 3Ø, 220/380 Volt 5 HP motor which I start on R and S phases livened at 230 Volts.
Between the S and T phases I use a 125 µF 400 Volts rated capacitor.
I use a 2 second timer to switch the Cap off after 2 seconds via a relay.
From the running motor 3 phase 230 Volts is available from the terminals to start other 3 phase motors, same or smaller rating.
The flywheel effect of the main motor (or idler) keeps all working nicely.
Sometimes I have to give the Heemaf motor a push on the pulley to aid it in starting.
It runs fine from a 16 Amps MCB.

The R-S-T are the older European phase markings now superseaded by L1-L2-L3 or R-Y(W)-B.

The 3Ø motor running from a 1Ø supply runs actually nicer than a 1Ø motor, because of the heavier rotor.

Also as Hero999 sais.
The US system is split phase with a common neutral. 110 or 120 Volts either side of the neutral 180° apart. so 2 hot legs on the socket for 220 or 240 Volts appliances.

In factories they have 120 / 208 Volts or 277 / 480 Volts three phase 120° apart which is true 3Ø.

In New Zealand mains voltage is 1 Ø 230 Volts 50 Hz between phase and neutral, or 3 Ø 230/400 Volts 120° apart.
In rural areas split phase is used and supplies of 230/460 Volts or 240/480 Volts are common. at 180° angle (similar as US).

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Attached is the set up I use at home.

The links in the motor terminal box are in delta set up.

e.g. 3 links in parrallel across the terminals

U-Z
V-X
W-Y

Attached Images

1phase to 3phase converter v2.GIF (21.8 KB, 22 views)

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Hi Ruuf,

I put my snowblower in storage yesterday and had a chance to pull the converter out. Unfortunately, I did not put the wiring diagram inside it. Pictures are attached.

I suspect my circuit is very similar to the simple circuit posted by RODALCO above. I used only one capacitor (black cylinder), a full voltage starter (big square thing), and a potential relay instead of a timer to drop the starting capacitor out of the circuit (square GE box in corner). Sorry I can't be or more help. It was not as sophisticated as those converters that have multiple capacitors and power factor correction, but I never had a problem with it in over 20 years of use. John

Attached Images

	3PH converter_end_sm.jpg (119.9 KB, 22 views)
	3PH converter_top_sm.jpg (54.1 KB, 16 views)

 

I put a short clip on Youtube over the weekend.

I'm at work now, can give you the link later when i'm at home.

Look under Rotary converter or my user name Rodalco2007

It shows it in operation. Hadn't used it for a while so i had to give it a push to get up too speed.


Regards, Raymond

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Rodalco, I couldn't find your rotary converter on you-tube, although I did see some others. You're right about our mains voltage. I am rural, hence the two phase probably. I thought two phase might give you double the amperage , but I don't know, just guessing, don't quite understand it.
Jpanhalt, You've done a lovely job of you converter, looks very professional, real tidy.
I have my eye on a 5.5kw motor as an idler, they're not as easy to come by as I first imagined.
Thanks again for all your help