Single Phase to Three Phase Conversion

no, you cannt use one transformer to get three phases. but you can use one capacitor to splite pahse to get the three phases together with transformer. but its not a good 3 phases. many single motor use this method.

you can use converter, which rectifier at first and then convert to three phases with differnent time zone switch transistor or igbt .

I have 220 single phase coming into my shop.

Using a rotary phase converter I turn that into 220 3 phase and then use that phase converter to drive an identical motor from which I derive 440 3 phase.

I use the 220 and 440 three phase to drive power tools (lathes and milling machines) in my shop and it works like a charm.

Google (3 phase rotary converter) and you'll find all the needed info.

That is correct. A rotary phase converter is simply a single phase motor that turns a three phase motor. The three phase motor acts as a generator.

Another method is something called a VFD (Variable Frequency Drive). These are more expensive, but have a number of advantages over a rotary phase converter.

First, they are far quieter and consume less power, therefore more efficient.

They are much smaller.

They can change the frequency of the output signal and reverse the phase of the output. Altering the frequency allows you to speed control three phase motors with great precision. You can also dynamically brake a motor to stop it very quickly.

The down side is that they are two to three times the cost of a rotary phase converter, but for me the advantages outweigh the downsides.

"A rotary phase converter is simply a single phase motor that turns a three phase motor. The three phase motor acts as a generator. "

WHAT?????

What I meant was that you take a single phase motor and power that motor from your single phase source.

The output shaft of the single phase motor is mechanically coupled to a 3-phase motor, but instead of wiring the 3-phase motor to a 3-phase AC mains and drawing current, it is used as the generator. The 3-phase motor will generate a 3-phase current.

A generator is nothing more than an electric motor (as long as it has permanent magnets). You can try this with a toy motor. Spin the motor and attach a voltmeter to the motors wires.

Typically, motors have a speed of 1750 RPM in the US, so you match the single phase motor RPM to the 3-phase motor. That is, select two motors that have the same RPM rating and you are golden.

O.K. Anon., you're starting to confuse the hell out of me now.

"The output shaft of the single phase motor is mechanically coupled to a 3-phase motor, but instead of wiring the 3-phase motor to a 3-phase AC mains and drawing current, it is used as the generator. The 3-phase motor will generate a 3-phase current."

I'm assuming that you are referring to a standard 3-phase induction motor of at least 1 HP. If so, Where is the excitation current coming from? Are you exciting the rotor, or the stator to generate the magnetic field? If you're exciting the rotor, how are you doing it? I'm thinking that if you're on to something here, we can drive the 3-phase motor (generator) with a diesel engine and that combination would be a rather inexpensive alternative to commercially available diesel gen sets as large 3-phase induction motors are available from the salvage yards at very reasonable prices.

This is already being done.

Carrier Corp sells a unit called a micro-turbine generator which is a steam driven Baldor induction motor. It can't be used in an aschyronous application as it needs a source of voltage on its terminals to provide the excitation. There is already one installed and operational where I work.

Joe, What size is the one you have at your work? What are you using it for? Backup? Supplemental? Main? Experimental? Co-generation? etc. OR is this one of the "micro" units of about 100 watts?

FKIA,

The one I built uses a 5 HP 3 phase motor. It's at my home where I use it to run a 3 phase, 3.5 HP, 12" radial arm saw that I bought at an auction for $150. My total investment in building the converter was actually $0.00. I got the motor for free from the electrical training instructor where I used to work (retired) in exchange for a schematic of the final, functioning converter. The rest of the parts I had around the basement as I am a wicked pack rat. I can't throw anything away that looks like I might be able to use, and eventually I do. I built the enclosure out of 3/4" plywood, mounted it on casters, as is the saw, so I can easily move them around the basement. Even the plywood pieces were left over from another project. I gave it a couple of coats of machine gray paint.

FKIA, Sorry for the mis-understanding.

In my previous reply, I thought you were asking about the 3 phase converter I built.

The micro-turbine installed where I currently work (as a consultant) has a 3 phase, 460V, Baldor induction motor rated 260 KW (which converts to approx 350 HP). It's actually used as a demonstration showcase for steam customers wanting to upgrade from their old Terry-turbine driven generators to something newer and probably more efficient. The entire skid mounted unit is built by Carrier Corp.

Your approach is very simple and not completely true I am afraid, sorry to be negative!

A 3 phase generator is not just a 3 phase motor being turned by some other motor!!

If you ever decide to build one, check out what you need first fully and completely.......!

Andy,

I'm going to have to disagree with you based on the fact that we have a unit in operation where I am working. It is built by the Carrier Corp. and is sold as a turbine generator. It does in-fact use a Baldor induction motor, (as is stated on the nameplate of the motor) as a generator. As I previously stated, it cannot be used in an asynchronous application as it does not have it's own excitition system. The motor has to be connected to an AC source before it will generate any power. It uses the voltage applied at its terminals as the source of excitation which then induces a voltage in the rotor. The induced voltage in the rotor then produces the field magnetism. When the rotor is rotated at a speed greater than synchronous speed (3600 rpm), the stator winding voltage becomes greater than the applied voltage and power flow is out of the motor stator.

If you would like, I can get you information on the location of the manufacturer and you can contact them and verify the information I have stated.

I know the system, I know how it works, but that was not stated fully before, just a motor was stated!

"Just" a motor will not work!

Clarity, full description and accuracy always helps everyone.

But thanks for your kind note anyway, that was nice!

Hie !

You can actually use an ordinary three phase induction motor as a 3 phase a.c.

generator.I did it as a project quite some time ago. All you have to do is

fit 3 50HZ a.c. power capacitors on the motor terminals one per phase.These will provide your much needed exitation current.You can actually fit them and turn your motor shaft by hand and measure a small output.

E Dube

How about giving us a simple wiring diagram showing the motor, capacitors, connections to the exciting source and load.

Here's a schematic of one I built that works very well. Capacitor C-start is a fairly large value to get the motor rotating. The actual value would vary with the size of motor used. Some experimenting will be required. Once rotating, the start button must be released for the motor to reach full speed. The run capacitors function to balance the voltages at each phase. Hope you can read it. For some reason it didn't scan very clearly. The original is a lot clearer.

Joe, Thanks for the drawing. I can read it. I built one using a 10 HP motor and a potential relay to control starting 3 years ago and it is in constant service (24/7 for 9 months of the year). I just wish that the voltage on the manufactured leg were lower. My computer controlled machinery, which has phase loss protection, senses the higher voltage as a fault and shuts down a couple of times a day.

I could really use a drawing of the generator circuit that "E Dube" is talking about.

You cannot use a single transformer to convert one phase to three. For that, you should have a two-phase network and use Scott-transformer. The problem is that in a three phase system the energy flow is continuous despite the pulsing flow of a single phase system, so you have to "store" energy for the "no-input" intervals.

The simplest converter is the so-called Arno-motor. It's a simple three-phase induction motor. You have to start it and feed it on one phase and it will provide the proper voltages on the two other phase-coils. The single-phase side have to be sized to the 2/3 of the full electric load.

$100 is fairly cheap

http://web6.automationdirect.com/adc/Shopping/Catalog/AC_Drives/GS1_(120_-z-_230_VAC_V-z-Hz_Control)

404 Error...

add a close-parentheses to the end of the link, it got cut off.

I had noted a certain person on Ebay wanting to sell the wiring information for this transformer method he was using a tapped capacitor bank to shift one of the phases to a lesser or greater degree. His set of 3 ammeters and 3 voltmeters showed very good balance on each phase. He has some vidios on the subject.

I was going to broach this subject but you beat me to it, I had a good web search and have not found any wiring diagrams to date, as such I assumed this method was not very good as compared to the induction motor method. Still I am curious if anybody has tried it and can forward any info and links about it

A single-phase to three-phase electronic inverter would do the job, as would a motor-generator converter.

Application?

Voltage and FLA.

256 657 5191.

Easy to do.

Note to my first responce.

Transformer! NO.

They are 3 option that are easy ways.

you can use a self starting electric motor of 2x the power or buy one of the things that Ronk makes

I just built a converter to power a iron worker punch in my shop. I ordered a kit off ebay that consists of 2 start capacitors, 2 run capacitors, 2 definite purpose contactors, a resistor and a potential relay. I put it all together with my 7.5 HP 3 phase motor and I push one button and it starts. No need for a separate motor to start the 3 phase motor this way.The start capacitors get it to running the pot relay switches it to the run capacitors afterwards. I can run up to 3 7.5 HP motors from this set-up as long as I don't try to start them at once. The guy that I bought the kit from sells the finished product as well as the kits for which ever size motor you want to use. the 7.5 Hp one I bought was only 75 bucks which is far less than a static converter alone. There are hundreds of companies that sell static and rotory phase convertors if you do not have you on motor.

pipewelder

Hi,

I'll second your opinion since I built my own phase converter sourcing parts from an Ebay seller who provides the wiring diagram and components. The only thing I had to do is find a suitable cabinet to mount all the components and buy a 3 phase 7.5 HP motor. I added a 3 phase multitap transformer to balance the output so the voltage on all phases was the same otherwise a slight Imbalance exists. I was powering up an Industrial Argon Ion Lexel 95 Laser and the power supply wants a balanced feed. In your case you were powering up other 3 phase motors so they are less picky and can tolerate an imbalance. You are limited by the amount of current required to startup the 3 phase motor. I think 30 HP might be your limit in North America, then you better get a 3 phase power feed from your Power uility provider $$$$

Rick

You can generate 3 phase power by using a 3 phase motor (about 5 HP) and some AC capacitors. If your main supply is 230V, you'll need a 230 volt 3 phase motor. The 230 volts from the main supply is applied across 2 of the phases while the third phase is energized through one or more AC capacitors, sufficient to cause rotation of the motor shaft. Once the motor shaft begins to rotate, the amount of capacitance will need to be decreased to allow the motor to reach full speed. Once at full speed, the capacitance will require further adjustment to balance the phase voltages. It requires a lot more capacitance to get the motor rotating. This can be acomplished using a motor starter. The motor will now be generating 3 phase power which can be used to start and run another smaller 3 phase motor. Each 3 phase motor that is brought on line will increase the amount of 3 phase power available for starting another 3 phase load.

I have built such a 3 phase converter and it works very good.

I appreciate how the motor method works, but would like to see the wiring method for a 3 phase transformer?

I have heard of using transformers and capacitors to attempt to convert single phase to 3 phase but I don't think you can achieve true 3 phase power. Capacitors can give you up to 90 deg phase shift ideally so you might be able to get 3 phases separated by somewhat less than 90 deg each. I don't know how tolerant a 3 phase load would be of such poor power quality.

Check out www.ronkelectrical.com This is what they specialize in. I realize it's not as much fun as attempting to build it yourself and blow you and your equipment up in the process while you work out the bugs, but it off the shelf proven technology c/w a WARRANTY!

Some prototype of a transformer that corverts 1 phase to 3 phase was tried, but didn't work effectively. Motor-generator is the cheapest and sure way for now. The magnetic core of the transformer is the problem, not the winding. Lets develop technologies for this magnetic core.

We have used commercially available rotary phase converters to drive food mixing machines and the only problem we had was with solid state motor starters. The high open circuit voltage of the generated phase was seen as a fault by the motor starter and so it shut the system down. Changing to an older style motor starter with heaters solved the problem inexpensively. -- JHF

till this time all post are read you require three phase for your operation

that is about 30hp

best is use vfd drive only you may seperatly order the order for the same

as all are very low capacity with single phase you can boost single phase supply by step up supply for better capacity

jarunmagnet

Lindsay publications has a little book on: HOW TO RUN THREE-PHASE MOTORS ON SINGLE PHASE POWER.

If you want to run an induction motor as an induction generator you will have to use excitation. The mains supply will excite it for you. but you will need to try and turn it faster than the incoming frequency to make your meter run backwards.

If you want to run a star connected motor on single phase you will need a switch and a couple of capacitors,

GF

I worked with both standard ways (or most common ways) of generating 3 phase out of single phase and there are many considerations to be made when choosing which is best for you.

Rotary is noisy, inefficient and very bad at unbalanced loads. It is relatively cheap and very little set up needed therefor still the easy way to 3 phase for most.

digital or vfd is better on almost all points but watch out for noise on the neutral or earth leaks. They have little tollerance to current over neutral or earth and start to chatter. If your machine or equipment has dc drives in them do expect them to pick up this noise and respond to it in unexpected and undesirable ways. Shielding is the only way out of this problem so make sure your machine is addequately protected by design. They are more expensive but can be very accurately controled via input screens and almost do anything you want them to do power wise.