Input Voltage Correction

[Shane@profab]

Hi All,

I have a Tig machine that I want to use at home. The nameplate notes that its supply voltage should be 1ph 380V, its manual says it should be 2ph 380V.
(I did run it from my shop on 2ph 380 and it worked fine). The problem is that at home I only have 1ph 220V.
Would simply getting a step up transformer from 220 to 380 get the unit running?
(I did open it up to see if there was an option to wire it for 220V but there is not)

Appreciate any advice.

Shane

[PAToyota]

Never heard of 380V single phase being an option. You would need a phase converter to go from single phase to three phase, but the voltage would still be a problem.

What is the manufacturer and model of the TIG?

[Shane@profab]

In our neck of the woods (South Africa), most commercial/industrial applications are 3ph 380V, residential is then taken as one phase and neutral giving your 220v 1ph.
When I first encountered the machine I was quite curios cos as you say, single phase 380V is very odd, hence my opening the plug and seeing how it was wired, indeed 2 of the three phases are connected.
The machine is made by a German company callled ESS, the model is a 220TG VO, origanly designed for use with an orbital welding head and controller, which I have as well.
The company is not represented here in RSA, so I cant ask them.
I thought about a phase converter to go single phase to three phase, I am just not surte what using only two of the phases would do to it or indeed if it was required.
I am a Mech Eng by profession and my Elec eng mates are all light current experts so they are no help. What I do recall from my studies is that the power of an AC elec source can be determind by the area under the Voltage/cyle curve, so one phase has X amount of power, 3 phase and more area so it goes to logic that 2ph would sit somewhere in between - yes?

Regards

[PAToyota]

South Africa - that explains things a bit! :)

Not sure that I can help you. Typically a phase converter reduces efficiency, so I doubt that you'd be able to use one when you are also requiring more voltage.

[Sandy]

Not that this helps anyone here but here are a few tidbits of information to be instantly forgotten.

I look in my little Glovers Pocket guide under South Africa and it lists:

Single Phase; 230/380, 230/400, 250/433, and plain ole 250.

Three Phase; 380,-----400,-----433,------------------430.

Also shows all 50 cycle. Hmmm??

[Shane@profab]

Your guide is a wee bit out.
RSA being an ex European coloney all them years ago ,means much of our kit uses their standards.

Most, 3ph circuits are 380, to get to 1ph, divide by root 3 = 220. Do the same with 400v and get 240v.
Some places do have 400v.
Oddly the mines use 525V, apparently so nobody else can use their equipment!

That lot whilst mildly interesting, still leaves me without an answer, guess I will have to experiment a bit then.

Thanx
Shane

[onewyr]

here we go guys finaly something I may be able to help with. I the U.S. this is how it goes and it should be the same principal except for voltage levels. I residential u would have a 110v/ 208v service typicaly single phase but don't get it twisted u actually have 2phases an aphase and a b phase. From neutral to 1 hot would be like your lights and receptacles and the u can go from phase to phase and get 208v that would be like ovens, heaters and like ur AC 225 lincoln welder. now in south africa if ur voltages are 230v/380v I would say that from 1 phase to neutral would be ur lights and receptacles and if y went phase to phase would be what is called single phase 380. In some instances u have a 3phase service (or panel) and that is for big machines that would require 3phases. But for the most part all of ur household panels are single phase. 3 phase is usually for industry. if anyone has any other ????? just im me.
DISCLAIMER: I am an electrician here in america and know the power system here and not necisarily in S.A. In theory it should be the same principal because voltage is voltage. so if u don't research this further before trying it out and u burn up a machine you are on ur own.

[awright]

Shane, I think the nameplate says it all. If it says 380V 1 phase is OK, you're in luck. That means it is designed to work satisfactorily on 1-phase power, and all you have to worry about is the voltage and current. I would definitely not go the the expense and hassle of trying to supply 3-phase power with a phase converter.

All you have to do is get a 220V to 380V boost with output current comfortably above the actual maximum primary current draw of the machine. This can be either an autotransformer (a single 380V winding with a tap at 220V for the input connection) or a full transformer with 220V primary and 160 V secondary. This will be a cheaper transformer than a 220V to 380V, two-winding transformer because it does not have to handle the full input power of the machine and can, therefore, be smaller and lighter, using less steel and copper.

If using a full, two-winding transformer, connect the primary to the 220V power and connect one end of the 160V secondary to one end of the primary. Measure the voltage from the OTHER end of the primary to the OTHER (free) end of the secondary. If you get 380 volts, you are all set. If you get 60 volts, your secondary is connected in series BUCKING (opposing) phase and you have to reverse the secondary connections to put the secondary in series AIDING. Since the transformer is only handling a power level of (160V x Rated Current) watts, instead of 380V x Rated Current) watts, i.e., only about 42 percent of the input power to the machine, the transformer can be about half the weight of one handling all the input power of the machine.

Your main task now is to find a suitable transformer and be very careful or get an electrician to help you. I would bet that your machine would be quite tolerant of input voltage straying from 380V by 10 or 20 volts, especially if you never use it near full capacity. That should make it easier to find a suitable transformer.

Enjoy your new home TIG setup.

awright

(By the way, did your manual really say 2-phase or did you mean to say 3-phase in your original post? There is such a thing as 2-phase power, but it does not have the advantages of 3-phase power and I don't think it is ever used in power transmission.)

[onewyr]

(By the way, did your manual really say 2-phase or did you mean to say 3-phase in your original post? There is such a thing as 2-phase power, but it does not have the advantages of 3-phase power and I don't think it is ever used in power transmission.)
it is not called 2phase. when u are using 2 hots and no neutral it is refered to as single phase. In american residential from the power lines u have a 120v/208v or 110/220 volt service and what that consists of is 2 hots 1 neutral. on each hot u have 110v that is if u connect a multi meter from 1hot to the neutral. if u put ur multi meter between both hots u will get 220v. this is still considered a single phase circuit.

[MAC702]

I'm sure he is aware of that. There really is such a thing as two-phase, though. It is inconsistent with our current naming convention (how many ways to combine hots to get power) but it is essentially two hot legs that are LESS than 180 degrees apart in their sine waves. I learned about it myself last year. You (and I) will probably still never see it used, even if it is in use still anywhere...

[smithboy]

2 phase was (and may still be) used (actually generated) in the niagra falls area where hydroelectric power started. I saw a documentary about niagra falls and thomas edison, ac versus dc, and others folks in the bid'ness. I think it was on the history chanel. I love documentaries.

http://www.ewh.ieee.org/r7/hamilton/life_member.htm

[Shane@profab]

Gents, that was what I was looking - ta to all.
The manual does actually say 2ph 380V with the nameplate showing 1ph 380v.
If you look at the way the plug is wired from a simplisitic point of view, there are two phases and no neutral - if you measure phase to phase, you get 380V.
As for that dual supply to your house, we dont have that here in RSA. A phase is taking from the local feeder to your street, another phase to another street and so on and so forth.
I have seen in some African countries (where standards are a bit dodgy), the houses may have multiple phases, one feeding lights another plugs and geysers, sometimes you only have one phase working on a power outage - real odd.
Anyway, going to crack a frosty and pour (my eyes not the frosty) over that reply about the transformer tappings along with my copy of Hughes Electrical Technology.

Cheers

Shane

[Shane@profab]

Sorry, me again.

Awright, looked into Autotransformers from a theory point of view, seems fairly straightforward. One thing it does mention is that the common connection must be earthed to avoid serious shock risk, could you elaborate on this?
What is the disadvantage to this type of Tx as it cant all be roses?

Cheers

[MIG_Man_2]

Hi All,

I have a Tig machine that I want to use at home. The nameplate notes that its supply voltage should be 1ph 380V, its manual says it should be 2ph 380V.
(I did run it from my shop on 2ph 380 and it worked fine). The problem is that at home I only have 1ph 220V.
Would simply getting a step up transformer from 220 to 380 get the unit running?
(I did open it up to see if there was an option to wire it for 220V but there is not)

Appreciate any advice.

Shane

1P 380V!

ive never heard of that b4 and have been in the electrical field for 3 years now

thats crazy

[awright]

Shane, sorry I didn't notice your question earlier. Could you post the citation referring to the shock hazard of autotransformers? Is it possible that they are just saying that, for an autotransformer supplied by 115V, the common is the terminal that should be connected to the neutral?

Naturally, you must pay strict attention to the input wiring configuration of your welder and must use proper grounding of all metal parts of the welder enclosure and the autotransformer FRAME, but I'm not aware of any special risk of using an autotransformer. After all, some pieces of equipment come with the option of 208V or 230V connections, and these are basically autotransformer primary configurations.

In any case, it would be very wise to consult with an electrician (which I am not) before proceeding.

[awright]

Hello again, Shane:

I happened to be looking through, "Audel's Guide to the 2005 National Electrical Code," and think I may have come across an explanation about the safety of autotransformer installations.

"Section 210.9: Circuits Derived from Autotransformers," that autotransformers supplying branch circuits must have the common terminal grounded. The "not approved" wiring shows the autotransformer wired across two hot lines with 240 volts across them supplying 120 volts to a branch circuit. This would obviously be an unsafe configuration because the 120 volt branch has no neutral.

I don't think the same issues arise in you are not supplying a branch circuit that any arbitrary device could be plugged into but are, rather, adjusting voltage for a specific machine, with no provision for or possibility of plugging some arbitrary piece of equipment. In a dedicated piece of equipment, especially if you can mount the autotransformer inside the welder enclosure, there is no such hazard.

As I pointed out in an earlier post, it is vital that you know just what the internal wiring is at the input of your welder. For example, if the primary of your welder transformer has a center tap on the primary that is connected to ground or neutral, you would be in trouble with a plain autotransformer connected across two hot lines. However, with a fully isolated primary with only two terminals, no hazard would arise. I don't know for sure, but I don't think there is a reason for your welding transformer to have a center tap.

I believe that it is important to determine the exact input configuration of your machine, including any taps on the transformer primary and any ground or neutral points.

awright

[Shane@profab]

Hi Awright,

As a mech eng with a passing interest in the sparky bits, I can mostly see what you are getting at.
The trouble I have with the welding machine is that the main transformer has more than a couple of tappings (cant remember how many and its a big beast to move into the open and remove covers).
I will strip it again over the weekend and do a wee sketch, if you wont mind having a gander at that.

Thanks again

Shane

[awright]

Shane, while you have the unit open, and since moving and opening the machine is a pain (I know how that goes - mine weighs about 300 pounds), do you feel confident about measuring voltages of the taps? That would tell us a lot about what options you have. If the unit is basically a transformer with capacitor/transformer/air-gap HF generator and no electronics (i.e., with no semiconductors), there should be no problem energizing it at 240 volts for measurement purposes. If it has active electronics, I would not try it because you could cause problems with the electronics by supplying them with lower than design voltage.

Of course, if all the transformer taps to to well marked and understandable terminals, there may be no added benefit from measuring terminal voltages. But the usual case is that the terminal markings are either absent or undecipherable without a detailed schematic (which I assume you have tried to get), so measurements can help a lot.

What we would want to know is what the tappings are on the transformer primary and whether there are any floating windings intended to assist in input voltage adaptation. It is important to distinguish between such windings, which would be high current windings with heavy wire, and low current windings intended to supply power to accessories and auxiliaries. Sometimes hard to tell unless you can see the wire in the winding.

To test, you would measure voltage from neutral (if one is used) to all other possible primary taps. If potential primary windings (with heavy wire) have no or low voltage relative to neutral, they may be isolated windings and you are just measuring capacitively coupled stray voltage.

Don't try this unless you are totally confident of making such measurements. It is often quite awkward working inside a welder in the shop. Disconnect the machine from the power source, connect your clip leads to the terminals of interest, energize the machine, read the meter, and turn off the machine. Never try to touch probes to terminals and read the meter while crouched with your head inside the machine.

Measurements from neutral may not yield useful results because the transformer primary may not have a neutral connection. In that case, you would measure from each primary connection to each tap.

Be careful.

awright

[Shane@profab]

Hi Awright, hope you are still out there after all this time, will try and PM you as well.....

Anyway, to answer your last question, it is an active electronics type welder, albeit a 1st generation bugger (it has transformers and electronic boards).
Using your helpfull guide on autotransformes, i set about trying to have one built but seems its gonna cost me quite a few sheets. Many sad months of no welding passed until..
I happened across (and was able to barter for) a 3ph 380-220v transformer - happy days indeed, since I got it as a straight swop for an old cell phone!
Anyway, lugging the beast to the workshop, I studied the connections.
It is rated at 15kVA and has nine plus one terminals. The terminals are marked in sets of three's, (380V, 215V, 205V) with the last terminal being N for neutral. Its physically got three seperate coils, each wound around a common single large laminated structure. The (380, 215 and 205) terminals are all connected (seperately) to a wire comming from each of the coils. so basically, each of the three coils has four wires going to one of the 380V terms, 205 terms and 215 terms as well as the neutral term respectively. Hope I have been clear enough. There is elec conductivity between each term with about 0.4ohms.

My thinking is to use the Tx as a step up duty Tx, basically by bringing my live and neutral 220V supply into the Tx and then tapping off the req'd 380 phase. My question is, how would I physically connect this to teh set up I described and would it work to bridge the primary coils to each other and the same to the secondary coils, the idea would be to share the load across coils.

Phew, that was taxing...

Shane

[Shane@profab]

Looking at the number of views on this thread, its seemed to be an interseting topic, so I will post my subsequent findings now.

Spoke with a bloke with some elec background about my tx and he reckoned I should just put the supply on one of the 205V terms and on the nuetral. Then put the load on one of the 380V terms and that same neutral - I did not like the common neutral, but hey. what do I know. So rigged it all up on the input side with no load only a DMM, flicked the power switch and it buzzed loudly and tripped a 20a breaker! Didnt have time to see what the DMM read. Reckoned to myself that this was not the right way so decided to try a different tack.
Put the input lines on two of the 205V terms and DMM on tow of the 380V terms and tried again - result!! much less buzzing and 397V - happy days all over again.
Since the Tx is rated at 15A, i figure this to be 5A per coil but whats weird is that its marked 15KVA 205-380V 15A - that doesnt compute out in my elec calcs. Anyway, in order to check the suitability of load sharing across all three coils, this elec dude reckoned I should first ensure that the voltages were balanced on each coild, within less than 10V was his recommendation, checked each coils generated no load voltage and they are all within about 6V, so next trick is to hook the Tx up to my house DB and give it a bash, gotta be carefull tho' I only have a 60A feeder into the house, if that works, I have a complete water cooled Tig machine with soft start, soft stop and all this lovely things....

later

[awright]

Hi Shane:

I'm not sure I can offer much advice right now, both because I am in a rush program to get ready for a 5-day engineering test on railroad track and because I am not experienced in three-phase transformers.

However, I want to caution you strongly against just connecting stuff up trial and error and seeing if it pops a breaker. That's a good way to damage your transformer. Remember that circuit breakers are protective devices for fault conditions and are not intended to be used as routine protectors against repeated incorrect connections.

Bear in mind, also, that your transformer has no phase conversion function and you will not get 3-phase out of it with single phase input. Additionally, I don't think you can use all three windings with single phase input. Here's where you need knowledgable help, and I am not knowledgeable about 3-phase power wiring. Frankly, it's not clear to me that your electrician friend knows enough about 3-phase power either if he, "reckoned" that the transformer should be connected any particular way. Either one KNOWS how to connect power electrics or one should admit that he doesn't know and should get advice from soneone who KNOWS. In my opinion, trial and error has no place in high power electrical wiring.

I am having a problem understanding just what you did in your experiments. Hopefully, someone knowledgeable will wade in and clear things up for us. Until one does, I cannot spend much time on it, but I'll ponder until I am finished with the testing. It is entirely possibl that you will not be able to use your 3-phase transformer for your welder.

awright

[Shane@profab]

Hope this works, keep trying to post and then after typing mrathon, get booted out, so gonna keep this short and sweet.

Safety - noted and comments much appreciated, advice came from elec eng with post grad qual in power elec - my info was a bit vague.

Need single ph not 3 phase, hence the bridginb of coils.

Have now got it to work just using two sets of coils (live and neutral in, 2ph 400V out). Hooked up machine and she lives - cool!

Now must set about finding spares for my water cooled Tig torch, she is a bit old and they dont make this kind anymore.

Armin, ta for all advise, hope your test went well

Shane

[smithboy]

Congrats man. It's always good to breath life into something you thought might be dead.

[Shane@profab]

Yeah tell me about it, I was wooping and hollering around the house - wife thought I had finally gone nuts!
Been doing some stick welding with it and its SOOOOO much better than my old oil bath machine, its like living in a new world.

[awright]

Good work, Shane. I share your enthusiasm for restoring old machines to functionality. Very satisfying.

Can you show us a diagram and photos of what you did for future reference?

What's an "old oil bath machine"?

My track tests went beautifully. I was measuring the vertical deflection of transit system rails on different types of ballast from 50 feet away using an instrument of my own creation incorporating a laser, reflecting off-axis telescope, and a position sensing light detector. That's also very satisfying (when it works, as it did this time).

awright

[Shane@profab]

Armin (and others)

I will gladly post pics, will take some on sat morning and post from home - time lag between us will mean they come up ata strange time.
The best part of fixing this rig is that it is actually an orbital welding rig c/w controller and two orbital torches!

Oil bath - this is what I call those transformer based welders with the many different connection points for different amp welding with stick, normally filled with transformer oil to keep cool.

That track defelection sounds very interesting, just how much defelection are we talking about and what kind of resolution does your rig give you? Is the deflection done with static load or speeding Amtrak whizzing past your kit?

Ciao

S

[awright]

By inquiring, you risk being flooded with a long-winded (as I am infamous for) description of my track test setup, as the guys I am subbing to on the test and my wife all look back at me vacantly when I describe what I'm doing.

Basically, it is a way of measuring the amount of vertical deflection of a light-rail transit system rail as a test train loaded with bricks to a specific weight passes over track on different types of ballast at speeds from 15 MPH to 50 MPH. The sponser is trying to show the efficacy of shredded automobile tires as sub-ballast under the normal crushed stone ballast as a means of both (1) getting rid of the millions of tons of trashed tires and (2) controlling vibration transmitted to wayside dwellings. The measurements have to be made from about 50 feet away because the entire region under the track deflects under the load of the passing train, making it impossible to use a locally ground-referenced deflection measuring device.

I shoot a Helium-Neon laser beam, expanded to be about 1/2" wide and 1" high, onto a retroreflecting cube-corner target mounted on the rail, pick up the returned beam with an off-axis reflecting telescope, and project the focussed returned beam onto a position sensing detector that gives a signal proportional to the position of the light spot on the detector. Sounds simple, but it took many iterations to get most of the bugs out, the biggest of which was that the rail in the hot sun emits a huge amount of infrared light that swamps the detector. (I originally thought the test would be performed at night, but the transit authority didn't want to disturb neighbors at night.)

The last fix that made the system work beautifully was to insert a "hot mirror" that blocks the IR coming from the hot rail from reaching the detector, which is actually most sensitive in the IR range. I use a HeNe laser, despite the cumbersomeness and high power requirements compared with diode lasers, because I can then filter the returned beam with a $200, half-inch diameter filter that passes light over only a 1 billionth of a meter bandwidth centered on the HeNe wavelength. Diode lasers have too wide and variable a wavelength which would mean I would have to use a much wider passband filter that would allow too much stray light in to the detector. The rail deflection under a passing train loaded to full seated passenger capacity varies from about 0.03 inches to about 0.1 inches, depending upon the type of ballast. The transit system operators are concerned about rail stability over time and rail stress due to bending. The guys I'm subbing to measure wayside vibration with geophones and rail stress with strain gauges. Fortunately, I don't have to write the report. I just supply a calibrated deflection signal to their recorder and I'm finished after the last train passby.

There! Thanks for giving me an audience. I finally got to tell somebody.

awright

Oh. Yeah. The connection with welding is that I welded up an 80 pound tripod of 3" channel and a 1" thick steel top plate to provide a stable platform for the telescope. That was vital because a very sturdy wooden tripod for an 8" x 10" view camera that I inherited from my dad was far too wobbly.

[awright]

Did I finally figure out how to attach photos?

Well,just barely.

awright

[Shane@profab]

photos as discussed (hope this works)
Now Ive uploaded the photos but cant see them as I type this, mmmm

for a man known as the curios mind slave, there is no such thing as too long a response, if you are anything like me you would have gone into this thinking that everybody else was an expert and would have asked them, then you would have decided that that are just posing as experts and set about becoming a real expert yourself...

Anyway, photos should show the terminals ( I cant get the shake out of this Nikon camera,) and the clearer one shows the machine....yes yes, the Tx is in wooden box, I didnt want to wait to use it and with a 2 year old running around I wasnt prepared to just leave it open while I tested.