Welding Pulse Monitor

[chy_farm]

I haven't ever seen real welding wave forms either in direct current welding for steel sheets or alternative current for aluminium, magnesium.
if I was able to see them it should be informative in determining several important setting values.

So I tried to set up a current detector added to my welder, by applying a hall effect sensor unit being sold on the market, at around the ground cable of my old analogue welder.



Red curves with arrows tell how welding current goes while the arc melts metal, it might sound funny to you since the arc emits out of the torch yet the current runs to the adverse direction. This is why in TIG welding the welder uses minus electrons coming out of the torch while giving heat to the spot, so the polarity of this torch should be minus and the ground (or the metal to be melted) are plus.

[chy_farm]

The purpose is to further optimize my old analogue welder, welding current and welding wave forms when she has to weld thin aluminium sheets in butt-joint.

With my novice skill job of butt-joint with thin aluminium (like ones with 1.5mm thick) has been a tiny thorn in the throat. For one thing aluminium filler did not want to melt in to the starting welding pools when I have to weld both ends of the two sheets at several intervals, especially in welding this thinner alu sheets.

I know pros can do it better, but it's not about myself, so tried to find another way to make it better, and found one called the MIX-TIG, a way to generate alternative current for thinner aluminium while mixing some percentages of direct current to the aiming target.
Anyways this should be posted on another thread soon after this.

The composition is like this;

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We need some handy oscilloscope one like this;

[chy_farm]

This hall sensor is named HAS-50, which allows to detect current up to 50 amperes, and is made in USA.

I thought it only detects current below 50A, but found it can do good job either for current above 50A.

[chy_farm]

Showing an oscilloscope view of an analogue wave form consists of 12.5% (this percentage is called "duty ratio") pulses when i did a DC welding with the pulse switch ON, to a sample steel sheet.
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The pulses come downward to reach nearly -8.1V in this view, but we have to calculate the real amperage by making it 10 times, and replace the unit form volt to ampere, so this means the peak welding amperage is minus 81 amperes.

[chy_farm]

For a better comprehension, gave a small modification to the view above, added the wave-form-layers to see the current going further;
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We can only melt steel sheet with the 'Welding Current' of the pulse, while we make repose when the pulse is off.
This repose-period when the pulse is off, we call the current of this period 'Base Current'.

Thinner sheet are easy to be melt-down, so we beginner love to use this trick, melt the target in short period, then make repose to cool the target down for a while, and repeat and repeat.

[DIYer]

Thanks chy_farm! We've added your Welding Pulse Monitor to our Electronics category,
as well as to your builder page: chy_farm's Homemade Tools. Your receipt:

Welding Pulse Monitor by chy_farm

tags: measurement, welding, oscilloscope

[FEM2008]

This hall sensor is named HAS-50, which allows to detect current up to 50 amperes, and is made in USA.

I thought it only detects current below 50A, but found it can do good job either for current above 50A.

Pretty nice project. Thank you for sharing. I thought that sensor looked familiar. The maker of that sensor used to be the parent company of my work.

Cheers!

[Carnel]

Hi Chy_Farm,
Your post is very interesting so thanx for it. I have a question. You mentioned you are using an old analogue welder. Perhaps I am wrong but my idea of an analogue welder is a welding transformer with large and adjustable spreading inductance to limit the welding current. But how are the pulses created? These 13 msec pulses with small rise and fall times need a semiconductor to switch these pulses on and off. Can you please tell something more about this "old analogue welder"? Or should I better wait for your following post?

[tonyfoale]

I was about to ask the same as Carnel.
By analogue do you mean that the controls are separate rotary knobs rather than stepwise control by button presses.

[chy_farm]

Carnel and tonyfoale, good evening.

Thank you for having interests on my project. Since I am a beginner in electronics and still learning things by books and internet pro-sites, I may be wrong either, but anyways I am going to try to show what I know about my old analogue welder.
Posting an image map to illustrate my understanding below, but as far #6 I am yet on the way learning it, so I may not be able to give good replay on this.

> By analogue do you mean that the controls are separate rotary knobs rather than stepwise control by button presses.

You'r right Tony,



Chy

p.s. I see an image below which I tried to delete, was not able to...
p.p.s. Was able to do it.