Such a difference!!!

[Kent]

If you ever try a fronius or an ESAB inverter three phase stick welder you'll be amazed.

Never noticed a great difference in stick plants beyond a certain point. Talking 3 phase off the major players.

 

[normspanners]

Why are engine drive welders so good? At the end of the day they are basically a generator/transformer powered by an engine with no electronic trickery, why are they so smooth?

High frequency about 500 hz as apposed to 50 that is why they sizzle and squeal

 

[normspanners]

• The ones I have used use HFDC , or a form of chopped dc

What is high-frequency DC? I thought that DC meant unchanging voltage (like a battery)?

Your understanding of what is meant by the term DC is not correct. There seems to be a lot of confusion about just what the terms AC and DC mean.

In the field of electronics,

• AC is used as an abbreviation for the term Alternating Current which is a condition that exists at any time that electrical current flows in two directions within a given electrical circuit, with the number of the current reversals typically occurring at some predetermined rate over a given period of time.
• DC is used as an abbreviation for the term Direct Current which is a condition that exists at any time that electrical current flows in one direction only within a given electrical circuit (i.e., from a positive electrical potential to a negative electrical potential).

Direct current flow can have a number of forms:

• a constant electrical current (which would be the case where a constant electrical voltage flows in a single direction within an electrical circuit with a unvarying electrical load resistance), OR
• it can be constantly varying as the result of changes in supply voltage and/or electrical circuit resistance changes and/or electrical circuit load changes.

It is still Direct Current as long as the electrical current flow is in a single direction. Such current can vary in an infinite number of ways and still be DC as long as current flow in held to a single direction within the electrical circuit.

In the ZENA mobile welding system, the term high frequency DC (HFDC) has a very special meaning:

With the ZENA welding system, the term high frequency DC is used to describe a special condition where the direct current flow in the welding circuit (arc) is caused to vary, very slightly, in a special way, under electronic control, with the tiny variations happening at a very high speed, so as to produce greatly improved welding characteristics when compared to a conventional welding current generating system of the type used in standard engine driven welders, or in welders which use automotive alternators as welding current generators (which often refer to high frequency DC in their specifications).

In the ZENA welding system the high frequency current transitions / variations occur at least 18,000 times per second, and will typically exceed 21,000 times per second.

HFDC current provides a three very substantial benefits in the ZENA welders:

• HFDC creates electrical agitation of the welding puddle (you will hear a high pitched whistling/whining tone coming from within the puddle while you are welding). This puddle agitation process:
  • works to facilitate the removal of impurities from the weld puddle, and to
  • improve weld penetration by moving hot metal from the center of the puddle towards the edge of the puddle and cooler metal toward the center, allowing the arc to melt additional metal in the areas surrounding the puddle -- for a given current setting, and to
  • significantly improve over all weld quality by insuring that the metal which makes up the bead and the metal surrounding the bead are more homogeneously mixed with each other and that heat within the bead is more evenly distributed.
• HFDC also improves the ability of the welding cable to transmit DC welding power from the generator to your electrode -- reducing the effects of welding cable DC resistance and internal impedance -- allowing us, of a given welder, to use welding cable with a smaller cross sectional diameter than would other be necessary for proper welder performance
• HFDC also works to increase the stability of the welding arc and allows an operator to achieve excellent welding results with both a shorter than normal welding arc (down to 0", in many cases) OR a longer than normal welding arc (up to 2X welding rod diameter). Inexperienced welders find the welder to be much easier to use and with much better results than a conventional welder can provide -- pros find it much easier to create x-ray quality welds and, at the same time, find that top quality results take less effort.

• HONDA GX200 OHV petrol engine with oil alert
• High rated duty cycle of 150 amps at 60%
• Extremely economical fuel consumption of just 1.1 litres per hour
• Patented digital welding control
• High Frequency chopped DC self-exiting brushes
• 1500W single auxillary
• 110V DC socket for fixed speed power tools, lighting etc
• Welds any type of electrodes including Cellulosic
• Welds 4.0mm electrodes
• Patented auto idle control
• Overload protection
• Carry Handle
• EEC noise compliant - Silenced

 

[Kent]

Really? I have, when I went from a inverter fusion to a fronius transpocket it was a world of difference, then when I used an ESAB at

I have never used that first set, perhaps it was bobbins? Seriously contracting in Jan I was swapping from Lincoln. Miller. Esab and one I can't remember and no great difference or rather any I noticed other than I didn't have to drag one about

 

[penfold]

HFDC also improves the ability of the welding cable to transmit DC welding power from the generator to your electrode -- reducing the effects of welding cable DC resistance and internal impedance -- allowing us, of a given welder, to use welding cable with a smaller cross sectional diameter than would other be necessary for proper welder performance

I don't know about the other stuff but this claim smells strongly of snake oil.

 

[normspanners]

How can they have a higher Hz @normspanners engine drives put out DC current. Not AC

OH they must be wrong then http://www.sgs-engineering.com/sw200ac-welder-petrol-generator
Also not mighty midgets they are ac at 500 ish frequency then rectified to dc
similar to a car alternator. giving a high frequency dc

 

[normspanners]

Well you asked a question and I gave a few answers, I am not bothered if you dont like the answer quite a few various welders employ HFDC now.

 

[Seadog]

I think the point of the high frequency chopper circuit is that it is able compensate for fluctuations in engine speed whilst presenting an output that is, to all intents and purposes, pure d.c.

The best of both worlds.

 

[Jim Davey]

 

[normspanners]

But that was only part of the answer ! and what has this country got to do with anything !
You inferred engine drives put out pure dc, and therefore have no frequency but they dont all emit pure DC, and some utilise various methods of utilising ac and dc frequency whether it is pure sinusoidal ac or chopped dc.
I mainly used that quote because it explains nicely the misconception that engine welders use a form of pure dc and saved me a lot of typin
so what ?
I have used their engine driven automotive welder, for a quick weld repair and whilst it might be sales hype it was still a very acceptable form of welder and I was pleased with the output.

 

[Jim Davey]

My two pennies worth is that if you take any machine designed to do arc welding to a high standard it will do it very well. Regardless of the method of power, be it mains, or infernal combustion. Technically a mains set is running off a generator (what else is a power station?) and it will usually be a much more stable and consistent supply than from your average petrol or deisel welder genny will provide.
I think where people form an opinion of what is better or not is as a result of unfair comparisons between welders and certain types of rods that just run better on the older engine driven sets.
Now going back to the days of machines like the Lincoln SAE 300 they had an amperage range and a separate adjustable voltage range. This made them perfect for running certain types of electrodes as they wouldn't snuff out in a root like some do.
However, lying in a wet pipe trench with a 110 volt cable wrapped around your arm with a live rod in it is unpleasant at best, and fatal at worst, so legislation has dictated modern sets need to operate at reduced open and running circuit voltages. This means that old types of rods formulated to work on sets with high OCV often don't like modern kit.
These days sets do not have adjustable voltage, the characteristic relationship between amps and volts is fixed by design. Meaning rods have had to change, there are rods that run brilliantly off new kit at reduced voltages but you have to ask about them. If you select a 60 year old design of rod, made to work with an obsolete form of machine then results may well suffer.

 

[normspanners]

Thanks Jim I agree with your post ( I cant disagree because it is factually correct)
the point I was making earlier is that the old midgets used a form of hfdc not pure dc as in battery power at a much higher freq than the mains whether single or 3phase, and things have progressed over the years .

 

[Jim Davey]

Yes, and that is why the sound and weld the way they do. It was a way to make the output smoother and it worked.

 

[normspanners]

I think the point of the high frequency chopper circuit is that it is able compensate for fluctuations in engine speed whilst presenting an output that is, to all intents and purposes, pure d.c.

IIRC it is not a circuit persay in the old midgets for instance it is the fact they are an alternator which is chopping the dc when rectified some say it is that action of that pulse that keeps the weld puddle free of contamination
either way they are very pleasant to weld with ( with ear defenders !) or very long leads !
when I worked at a plant firm the welder used to use the midget as his prefered weapon when hardfacing buckets etc.
Very annoying for all the techs though and all you could hear at dinner break was a mass TFFT

 

[normspanners]

HEHE thing is with the midget, it made you WANT to pick up another rod and seemingly 'pour' it into the metal.
Also people say they were thirsty, they where especially when keeping the welders car running back n too to work. on a 50:50 basis.