Miller syncro 180 vs maxstar 200---- help needed bad :-(

I am ready to bite the bullet and get one of the 2 machines.
miller maxstar 200 SD $2000 with accessories DC only inverter type
miller syncrowave 180 SD $1500 all complete AC/DC transformer type
I only have 220 V 50A tops to work with
material mild steel and stainless up to 1/4 inch.
I am stuck between the rock and the hard place.
I like the maxstar due to its portability even tho it will be used in the shop , I like the low power consumption and auto line voltage from 110V-460V in case I need to move it. rated 175 amp at 60 % duty cyc. sucking only 17.5 amp.
on the other hand the syncro180 offers A/C which I do not need at this time but who knows what the future holds. $500 less , it is rated at 150 amp at 40 Duty cyc. sucking 54 amp...... is my worry.
what do you guys think ???? there is plenty smart guys out here , give me pointers before I buy the wrong machine.
thank you
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I went through much the same logic and then bit the bullet hard and bought a Dynasty DX (a machine much beyond my current ability). The same solid state technology that enables an inverter to weight 40lbs instead of 240lbs makes it possible to vary just about everything with the AC frequency and waveform. What I am saying is the $500 you will probably spend to add AC to the inverter by purchasing a Dynasty model is not purchasing the same AC capability as you would get with the 180SD. Whether of not you need that capacity, or even AC is another matter. Someone with more experienc using the two machine types can take it from here.

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I don't have the Dynasty, but would like to have one. Anyway, I love my 200DX. I have used it from very thin process tubing TIG and up to 12" sch 40 pipe stick without letup just to see if it would hang. I am very satisfied with my Maxstar.
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Well I have a Maxstar 200DX and love it dearly. The real question is ... Within your price range, do you need AC TIG for aluminum or not.
If you really need AC TIG in that price range, then Buy the Thermal arc Prowave 185TSW for $1750.
The one thing that a Maxstar does is plug into any voltage available, so if that is important then there you go.
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If it is strictly for shop use, I'd buy the 180SD (in fact I did). Realize that most of its high amp draw is reactive current, which won't show up on your power bill (ie current is out of phase with voltage, so it doesn't actually consume watts). You can add power factor correction capacitors if it bothers you.
I prefer the 180SD because it has HF and AC, and because of a belief that transformer machines are more rugged, and repairs, if needed, are cheaper. You don't get HF or AC with the inverter, and if it breaks, repairs are generally much more expensive. You may not need aluminum capability now, but if you have it, you may find you will use it more than you suspect.
OTOH, if you are going to use it in the field, you don't intend to keep it beyond the warranty period, and you're sure you won't be doing aluminum, then hands down it is the inverter. It is simply a size and weight issue.
Gary
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wrote:

please tell me what would be involved in this (above ) power factor correction. and also how would the syncro 180 act on a 6 gauge- 50 amp circuit ? would it choke it welding limit or would it risk over heating my wiring ?

it would be used in the shop 99% of the time, but I was thinking about if I ever needed to do repair on anything that is not in the shop ( example , want to put a gate in my fence or other odd repairs. things that does not fit in the shop or can not be moved to the welder. again these are just things that Are factors, which may only come up once a year. At this point I really think that I do not need AC the maxstar does have HF start, and DIG control for stick.
it is at tough chioice.
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You'd simply wire motor start capacitors across the input line (at the welder) until idling current (measured on the service panel side of the line) drops to a minimum. There will be a particular value which results in minimum current. Smaller or no capacitance and the current will be larger, larger capacitance and the current will be larger too. This isn't a real sharp response, you only have to get reasonably close to the correct value to get benefit from it.

I rarely run more than 130 amps welding current, so a 50A circuit works just dandy with no power factor correction. *With* power factor correction, it'll run fine on a 30A circuit.

Yes, it is.
Gary
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Gary, can you give me little more detail on this , above. why would it not consume high wattage ? if the spec sheet say it will pull 54 amp on 230 V (at rated duty cycle , which is 150 AMP) are you saying it will not pull 54 amp ? ( 54A X 230V) = 12 KWH
I am clueless about this
thanks
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Ok, welding at 150 amps with an arc voltage of 20 volts (typical arc on value) gives 3 kW. Now transformers are very efficient, better than 90%, so the required input power is about 3.3 kW. This is real power. It makes the meter on your house spin.
But a transformer primary winding is also an inductance, and in an inductance current lags voltage by 90 degrees. In other words, when the current is maximum, the voltage is zero, and vice versa. So the real power is zero in an unloaded transformer primary. That's a good thing too because the transformer primary is a piece of coiled up wire shorting the input line. If it weren't for the winding inductance, there would be smoke.
Reactive power, called VAR or volt-ampere-reactive, isn't dissipative. The current generates a magnetic field as it rises, and when the current falls, the magnetic field collapses which induces a current. In simple terms, the energy is simply handed back and forth between current in the wires and a magnetic field in the transformer. No actual power is consumed. VARs won't make the electric meter on your house spin.
Ok, no power is consumed, but the "circulating" currents can get *quite* large. This is where the bulk of that 50 amp draw is coming from. It can be corrected, or more accurately it can be counterbalanced, with capacitors.
In a capacitor, current leads voltage, just the opposite of an inductor. By choosing the correct capacitor value and attaching it across the line at the welder, you effectively *cancel* the reactive circulating currents on the supply wiring to your welder. So the wiring and the breaker only need to be sized to handle the *real* 3.3 kW the welder draws, and not the reactive circulating currents it also has to have internally to operate properly.
Inverters have reactive circulating currents too, but they keep them inside the inverter because they first rectify the input line to DC, smooth it with a capacitor, switch that off and on rapidly to drive their inductor (a toroidal transformer), and rectify it again before feeding it to the welding leads. The conversion steps to DC either side of the inductor *trap* the circulating AC currents inside the inverter. So the outside world never sees the circulating reactive currents.
If you use power factor correction capacitors on your conventional transformer welder, the outside world won't see its circulating currents either, and it won't draw more current from the wall than the inverter would.
Since VARs aren't real power, and don't cost you any money, transformer welder manufacturers don't include power factor correcting capacitors with their welders as a matter of course. In effect they're letting the utility power grid act as a giant capacitor. But if you have limited current supply, inadequate service wiring, etc, then you can add those capacitors at the welder yourself and avoid having to upsize your supply wires and breaker.
Gary
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wrote:

Gary ,
would you kindly e-mail me at this addres please , zsebi_itt@hotmailDOTcom (correct the "DOT")
i like to ask you a few things off line if possible.
thank you
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I do not munge my address. Simply email me at the header address and I'll get it. Make sure your return address is not munged. I will not try to sort it out. If simply hitting reply doesn't work, then you won't get my reply.
Gary
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Thanks Gary, the email listed here is fake. i am getting 100 junk e-amil / day as it is. but I did get the other one from you this morning. and replied to it.
This capaciter info is crutial to me, because of the limited current 50 amp braker on a 6 gauge wires is all I got, and the syncro alone would push it to the max. There for putting the power correction in place would allow me to buy the syncrowave and save some money vs. buying the maxstar200 inverter, which would run happy on the 50amp braker. If I will be able to manege instaling the caps with the purchase of the syncrowave , I will be left with a little extra cash :-) and use it to get a water cooler torch for it.
speaking of water cooled , I will post a new tread about this.
thanks
wrote:

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Gary, it is always a pleasure to read your posts. You do a good job of explaining these things! I have to admit that I'm not sure I entirely understand the power factor correction, but I definitely have a lot better idea than I did before about the way transformers work. (I've always wondered how a transformer doesn't just short out the primary, and whether a transformer consumes power when idling.).
At the risk of asking a really dumb question -- if the capacitor cancels out the effects of the VAR (did I even say that right??), does it also mess up some of the desirable characteristics of a transformer -- for example, does it change the waveform going into the primary? For that matter, I thought a capacitor looked like a short circuit to an AC current?? I'm not even sure what I'm asking ... but I guess this power factor correction almost sounds like getting something for nothing :)
Thanks for any further enlightenment!
Andy

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On 10 Sep 2004 08:51:31 -0700, snipped-for-privacy@duke.edu (Andy Wakefield) wrote:

Thanks. Transformers do consume power when idling with no load, but only the power lost as heat in the windings. In a well designed transformer, that's not much.

Power factor correction doesn't mess up the transformer characteristics. All it does is substitute the capacitor for the grid as a source and sink of the reactive currents flowing in the transformer. As far as the transformer is concerned, nothing has changed. But as far as your shop wiring, breakers, and the grid are concerned, things have changed. Current draw is reduced sharply, which is the purpose of power factor correction. The only current drawn from external sources becomes the current associated with the *real* power drawn by the load attached to the transformer (and the small wire heating losses I mentioned earlier).
Now if you were to put the capacitance in *series* with the transformer primary instead of in *parallel* with it, bad things would happen. Basically, current would flow through the primary as if it had zero reactance, in other words, it'd act like it really was a short circuit.
A capacitor is no more a short than a transformer winding is, but there is one very big and important difference, the sign of the reactance. By convention, inductors have positive reactance and capacitors have negative reactance.
When either is used alone, the same circuit behavior results (aside from different voltage and current lead-lag behaviors which, while key on a deep level to what we're doing in terms of power factor correction, are a bit more involved than I want to go into here).
When we combine capacitors and inductors in various ways, we have to use complex vector arithmetic to model the resulting circuit behavior. I'm not going to try to give a course in AC electronics here. There are plenty of books which do that. Suffice to say things aren't always as simple as DC when dealing with AC reactive circuits. It is really hard to explain properly without lots of equations and diagrams. You can find those in books, but reproducing them here in a plain text usenet newsgroup is difficult.
Gary
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Gary,
I have also been considering a SD180 and had similar power supply concerns. Power factor correction sounds like it could help me.
For the caps for the power factor correction do you have a ballpark start point for mfd to start with.
Did you mean "run" caps? I thought start caps would not take continuous current.
Thanks, Glen
wrote:

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300 uF

I certainly did mean to type *RUN* caps. Do not try to use motor starting caps. They will fail explosively.
Gary
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