Can someone please give a quick description of how a converter works?

Any good books on converters?

I saw a basic diagram of a converter but didn't understand how the single-phase line became 120 degrees apart.

Although they make commercial products, there’s some interesting info at sites like www.gwm4-3phase.com and www.phaseconverter.com

From a D-I-Y vantage point, usenet newsgroups rec.crafts.metalworking and rec.woodworking address the subject periodically in motor FAQs.

Because the output of virtually all converters is 3-wire, there is no wyepoint neutral to connect to or measure, so no 120°-wye service. They are closer to a 240V Δ system, or maybe 240/120V 3ø 4-wire open-Δ. This gives you the “original” 240V—L1 and L2, and a second approximately 240V that is shifted by roughly 60° for L1-L3; giving around 240V for L3-L1. Don’t expect very tight voltage balance—that is generally implied when reading converter-manufacturer literature.

Because converter phase-to-phase voltage can be fairly unbalanced, so significant motor-horsepower derating [about 57% in some cases] may be necessary. Rotary phase converters have to be started and up to speed before running any connected 3ø motors. Don’t plan on powering any controls from the phase converter—they are not generally stable/regulated enough for that.

Don’t forget NEC ARTICLE 455.

In a nutshell, it's like a UPS with 3 Phase output (per "Static" Converters).
The 1 Phase AC may simply have a 3rd line created, or the entire AC is converted to a 3 Ø system.
Either way, AC is converted to DC, which is then Inverted to AC.

If this was a Rotary Converter, it would be a 1 Phase Motor driving a 3 Phase Genny (Generator).

Better explainations may be done by others, or if I get proper data, I'll post it.

Scott s.e.t.

p.s. pay no attention to the following text. Just trying out some extended characters.

¡ ¢ £ § © ª « ¬ ­ ® ¯ ° ± ² ³ µ · ¹ º » ¼ ½ ¾ ¿ × Ø ø

On those extended characters which combination of keys produce the ' ohms ' symbol and the ' square root ' sysmbol ?

Gwz,

Not sure myself what the keystrokes are for these symbols (Omega and Square Root).

They are simple ones with True type Fonts - Omega = W in the Greekx Fonts, Square Root = alt+0214 in the Symbol Fonts.

If anyone knows what the keystrokes are for these two symbols - using the plain Courier Font, please let us know ASAP!!!
(not a True Type, Postscript, or SHX Font - just an ASCII basic Font)

TIA!!!

Scott35 s.e.t.

"alt-251" (not 0251) gives the root symbol, ã but it does not translate correctly to e-c.net posts.




[This message has been edited by Bjarney (edited 01-15-2003).]

"alt-234" is {omega} from http://www.asciitable.com but it does not translate correctly in e-c.net posts.

Some call this chart 'code page 437' but not sure exactly why. http://www.nefec.org/UPM/sibmext.htm




[This message has been edited by Bjarney (edited 01-15-2003).]

I am not going to do any projects myself, except inspect the installation of a rotary converter.

The diagram at www.gwm4-3phase.com/rotconn.gif is how the one I saw appeared to be hooked up (except for them using an extension cord and not having some FMC installed correctly).

This being my first time dealing with a phase converter, I had imagined two wires going in one side, and three wires coming out the other side. This is not the case.

The diagram, in essence, shows two wires going in and ONE wire coming out.

Or is this a case of single phase feeding thru two wires 180 degrees apart, L1, L2, with three phase coming out thru the same wires L1, L2 120 degrees apart and a third line, L3 being created?

Is it possible to have single-phase and three-phase current on the same wires at the same time?

Steve,

The method used in your explaination and on the converter shown on linked image is typical of the first type I mentioned in the first reply (creates a 3rd line).

The Motor(s) and the Converter will be connected to the 1 Phase power system, across the Ungrounded Conductors (or L-L).
The Converter creates a circuit which has a Potential Difference between the newly created "Phase Line", and both of the existing 1 Phase Ungrounded Conductors.

The offset is probably in the range of 60º or so, which will be sufficent to create a Rotating Magnetic Field within the Motor.

This is the simplest method of creating Polyphase from Single Phase, but it is also the "Crudest".

Scott35 S.E.T.

Steve, instead of visualizing it as a wye case, consider it more like a 4-wire-delta arrangement. There will still be ~240V between L1-L2 [and about ~120V L1-N and L2-N.] For the “manufactured” T3, there will be ROUGHLY 240V L1-T3, T3-L2 and ROUGHLY 208V T3-N, but don’t expect nice, even, symmetrical measurements like you’d see with conventional utility-type delta transformer service.

Also, don’t plan to power controls or other 1ø devices from T3 and any other lead. Voltage stability will be marginal (and likely disappointing) at best.




[This message has been edited by Bjarney (edited 01-25-2003).]

Thanks, I think I get the jist.

Are there any books anyone is aware of that might explain in more detail phase converters?

They get discussed from a d-i-y point of view sporadically at rec.crafts.metalworking and rec.woodworking

If you don't have a usenet account set up, then search in "Google Groups."

hey hey you guys there is the other companine they do make phase conveter also it called ronk conveter i belive if i rember the web address is www.ronk.com but if i did give you wrong one please do let me know i used the ronk they make few diffrent versions of phase converts both satic and rotary version i allready deal both of it it have good and bad each one if need more info let me know i will try to explain more about

merci marc

Steve T;

I am unsure of any books to suggest. Maybe try your local Library, or do a Google Search.

I can draw some simple schematics, but at this time uploading graphics is N/A (some problems need to be fixed with the ECN server).

Once this is resolved, I can post away again!!!

Scott35 S.E.T.

02.08.03 17:20:00

Thanks guys

For Ω, type ampersand-pound-8486-semicolon. Here is an example, but type it without the spaces to get it to work:
& # 8 4 8 6 ;

For &#8730, type ampersand-pound-8730-semicolon. Here is an example, but type it without the spaces to get it to work:
& # 8 7 3 0 ;

[This message has been edited by ThinkGood (edited 02-08-2003).]

I hope I can ressurect this old thread.

In followup to:

"Steve, instead of visualizing it as a wye case, consider it more like a 4-wire-delta arrangement. There will still be ~240V between L1-L2 [and about ~120V L1-N and L2-N.] For the “manufactured” T3, there will be ROUGHLY 240V L1-T3, T3-L2 and ROUGHLY 208V T3-N, but don’t expect nice, even, symmetrical measurements like you’d see with conventional utility-type delta transformer service."

Since a rotary phase converter can serve multiple loads, I have a question regarding the distribution of its output with a 3 phase panel. Is it legal by code to treat this as a 4 wire Delta 240/120V system as outlined above. Can the neutral be brought along from the single phase supply to serve 120V single phase loads at the machine, motor controls in particular.

It's nice to see a topic be resurrected two years and one month later to the day.

Hi, 2 things to discuss:

1.
1 phase to 3 phase converter. I built one years ago from a 5 HP Heemaf 3Ø motor which I start on 2 Ø with a 125µF capacitor to the 3rd phase to get a phase shift. The motor starts up perfectly, when up to speed a 3 phase 3 x 230 volts is available.
This is perfect to start up any 3 Ø motors up to 3 HP. which don't have to start into a heavy load e.g. lathe etc.
This is done from a 230 V 50 Hz supply via a 16 Amp MCB.

omega symbol. I still like to find the short way of getting it. While typing i like to acces certain symbols without to drop down to other lettertypes etc to get it.
Like i can type now alt+230 and have direct access to µ symbol.
Why is it such a pain with the Omega!!!
i have goooooogled for it but not really to successfull at this stage.

sorry i did forget to add that i automatically switch the capacitor off after about 5 seconds when the mototr is up to speed.
The 3 phase motor appears to be quite happy single phasing and runs a lot smoother than a 1Ø motor (less noisy) OK i know that i have not the full 5 HP available but that doesn't matter. it serves my purpose of a 1Ø to 3Ø supply in my workshop at home.

This subject has been discussed before, but a few points are worth mention perhaps;
The simplest mechanical means of obtaining a true polyphase ac supply from single phase ac is with a 'Motor-Generator/Alternator', comprising 2 pretty standard machines coupled by a drive mechanism.
I built one for my workshop- https://www.electrical-contractor.net/ubb/Forum5/HTML/000937.html

A more efficient arrangement is to have two stator frames arranged in line on a single shaft, known as a 'Motor-Converter'. A motor-armature directly drives a generating-armature wound on the same shaft. These were extensively used in ac to dc conversion for traction purposes and were generally reversible for dc to ac operation or starting. Of course, single to polyphase ac with such a machine is easily arranged.
Another type is the true 'Rotary Converter', in which both windings for motoring and generation are on the same armature and stator. Usually these converted dc to ac for traction, but single to polyphase ac machines can be built. You just need to get your head round the fact that dc or single phase ac currents operate simultaneously with polyphase currents in the same windings!
As to modern practice, these machines are hopelessly inefficient, noisy, short lived and expensive when set against solid-state switching devices. Commercial transmission of HVDC is a practical reality and conversion to true polyphase ac is regularly done for both domestic, commercial and traction end users. The small 'inverters' on the market for home workshop/light industrial use don't make true 3-phase, nor do the ingenious big 3-phase 'master motors' which others have described on ECN, leading to poor performance, 'only-one-tool-at-a-time' and lousy efficiency. I think a motor-generator set up as I described gives the best 3-phase for home workshop use. When you get out to the 5kva level, it probably works out not a lot more expensive, certainly more robust and low tech. The technology exists for a manufacturer [or home builder for that matter!] to make a device which will create true polyphase ac from single phase ac using solid state devices, but at what cost for components I wonder?

Alan