Yeah, all electrical wires generate magnetic fields. If you coil it up it enhances the field and makes it bigger, it also resists change in voltage (that's what inductors are for) and generates a lot of heat. They can go on fire if there's enough power running through them.
Didn't notice it no.
So, you seem to know about electronics, obviously more than I do. I think this is closely related to how a Tesla coil works? The transformers in a microwave work to control voltage? I've watched lots and lots of videos about electrical stuff and maybe because I got into welding fresh out of high school and have no education on the topic I have a bit of difficulty getting my mind around how electricity actually works vs the commonly held ideas most people have.
Like for instance, the shininess of conductive metals. I watched one video where it was explained that we are actually looking directly at the electrons around the actual atoms that make up metals. Then too, most welders work with straight polarity. Rod positive, work piece negative. The welders get the idea that current is flowing from the rod or electrode into the work piece when it's actually the other way around. The electrons are flowing from the negative side into the positive side and so you have the arc above the puddle and work while the molten metal sprays down into the work and the puddle because it's attracted to the incoming current coming up out of the work.
So, back to what you wrote about how the coils restrict For deep penetration we do have a process called flux core welding. Actually it's a bit of a misnomer as straight polarity wire feed also has a flux core but combined with a gas shield to protect the molten metal. That's more commonly known as dual shield welding. With the flux cored welding wire you use reverse polarity and the wire actually goes down below the surface of the parts being welded, creates a zone where the wire is burned off in the arc and the flux melts to rise up to the surface of the puddle.
Since there's no gas shield and only flux if you use straight polarity the wire burns off above the surface of the puddle and the work piece and has to go through some air to get there. The oxygen in the air will cause the molten metal to partially burn so you get a very poor weld that's brittle and has defects like porosity. Reverse polarity so your wire is negative and it welds very nicely. Try that with dual shield and it won't weld properly. Same with most stick welding jobs where you are using rods coated with flux. Some rods however have a different composition that works better with reverse polarity but since they aren't commonly used in the field we don't even consider it unless we are told which for me was never.
When I went to weld school many years ago we had a machine set up for just flux core and I suppose at the time I knew it had the polarity reversed but in the field, we always used dual shield until I was on a job where for the first time in many years they had brought us flux core wire for a process. I totally forgot and tried welding without reversing the polarity of my machine. Kept getting porosity, got pulled off that detail, yelled at and told I was a shitty welder but no one checked why and I didn't remember until I was fired at end of shift and thought about it. Then suddenly I remembered. Dammit.
Back to inductors how they cause the voltage to resist change. Are there inductors in our welding machines that we are controlling with a dial that we set? If so, having a coil in our welding leads messes up the settings so we aren't getting the reported readings of voltage at our work?
Hey, I noticed something very interesting on a tank job. So, the set up is that we have our power supply places at close to where we cut out a large door sheet to get into the tank with sheets of steel and other equipment. In this case during set up some safety idiot complained about the ground cable and wanted it as close to my work as possible. So, basically wanted me to not only run my welding cable to the work site but wanted the ground cable running there also. It made no sense but I did it anyway. The current was way too low, settings were way off and voltage was pathetic, so much so I could barely run a decent bead no matter what I tried. So I set up a short ground cable onto a bolt I welded directly to the tank as close to the generator as possible. Everything was working perfectly then. Being very curious I got out a testing meter and checked resistance of the longer ground cable and it was as expected. The longer it is, the more resistance in the cable. I checked resistance from the tank to where I was welding and went to a couple other spots much further from the machine to test. Through that huge steel tank resistance was almost nothing. Even my welding cable had normal resistance. It's the same distance so why so little resistance through a huge tank but much more through a copper cable if the distance is the same?
Only thing I can think of is that a huge two hundred foot diameter tank has so much more mass that the resistance goes down to negligible. The safety inspector demanding I put a long ground cable to the work area as well as my welding cable was effectively doubling the resistance. So, she was making me try to weld with a machine that was never designed to push through that much cable and I couldn't get the proper current even though I pegged out the dials. Looking at the meters on the machine was no help at all since they would be wildly off reality. After that, when setting up power sources I used larger cables and hard welded on tabs I could bolt onto with copper fittings, Enough to carry the load for all guys that would be welding. Don't want to do the math? Then easy rule of thumb is, if your ground cables are getting hot, or connections are overheating they are either too small for the load (You'll know by touch because they get hot), too long (stays cool but you won't get proper current) or the connections are not solid (gets hot directly at the connection and will even melt and or catch fire).
I never had a problem when using these simple rules to trouble shoot before even starting to weld. If stuff did overheat it was usually at a connection that would end up smoking. Simply cut the cable back a bit to fresh copper that looks clean and bright, wrap cable end in a copper sheet, (yes, it's in the tool supply) and tighten it down super tight until you can't tighten down any more. It would be nice if the suppliers included some sort of spray or paste to put on connecters. I haven't seen that on a job.
Of note how stupid this safety bitch was, she complained to plant manager about how dangerous our weld arcs were and made us put up shields every where to the point of being ridiculous. It did no good at all to explain to her that from 30 feet it's no more dangerous than a strong light. Just stay away, right. Nope, she didn't even want to SEE an arc ever. So we had to bring in more shields to protect people OUTSIDE the tank. WTF? Don't look through the door sheet or other access. Just walk by and don't look in and you're good. Nope. It's radiation. Uh, ya, like the sun is radiation in many spectrums. Try looking at the sun? Who does that? Who stares at the sun? No one, cause it's painful and can obviously make you go blind.
Then she totally destroyed her credibility. She walked inside the tank, came over to my work area and was bending over looking under the gap at the bottom of the shield and complaining that light was escaping and she could SEE the arc. I had to stop. I was so pissed off I searched the supply truck, found signs and red tape. Signs said, authorized personnel only. Red tape around access to the tank with signs everywhere.
The very next time she crossed over the red tape to come inside our work area I quickly walked over, told her in firm tones that this was a work area for welders. She was not authorized to cross over unless she clears it with the foreman and he's not going to give clearance until all work is stopped. No entry.
The foreman was super pleased with me as he was sick of her coming over several times a day, nitpicking and shutting down work.
Her safety boss was also an ass. Last day of work we spent 19 hours on the shift finishing up then welded in the door sheet and brought in inspectors to check and x-ray. Believe me, it was a safety bitch keeping those clowns happy. Confined space requirements went into place with check in and check out on a sheet, access monitor person signing us in and out all day, bitch bitch bitch with inflated egos every minute and arguments. Safety supervisor came over while we were installing door sheet and literally walked under the suspended load in total violation of OSHA. Foreman shut it down and had to violently shove him out from under the load and then stood around arguing with him why you never walk near a suspended load, much less walk under it. Duh!.
Next morning was clean up and load out but safety supervisor came and tried to derail us before we even got started. We had been allowed to come in an hour late at 7 am because we had gotten 19 hours in the day before and were obviously tired. That one hour extra of sleep and knowing load out would be a breeze had us pumped. We are going to get a safety bonus with a completion bonus which means a huge paycheck on top of overtime we had been putting in all week. We are jacked up and ready to go. But no, safety ass tries to act all concerned about our safety and we are tired and should just take the day off, blah blah. Foreman told him no. We're loading out and that's that. So he takes a poll. To a man we all said we were fine and eager to get started so he turns around in a huff and walks off. Hey, he called for a vote and got overruled by the grunts. Tough shit.
Heck of a read. I can't tell if you're actually looking for answers or if you're subtly trying to tell me you know way more about electricity than I do (if so you're probably correct). On the off chance that was an actual question about the tank I don't think it was mass so much as capacitance, although that might've been what you were getting at.
The safety wombles sound fun. I can kinda agree about access monitors to sealed spaces though: Friend of mine works in aviation and one of his horror stories was about a guy who passed out doing maintainence on the inside of a fuel tank. No one knew he was in there and they refuelled the plane. They didn't find him until the plane landed somewhere else.
Geez, what a horrible way to die. So, obviously no hole monitor person with a clipboard. Once we put up the door sheet the safety watch becomes hole monitor with a clipboard. Go out or in and you get checked off with the time of entry and time of exit.
On a ship they are far more lax but maybe shouldn't be. I've rarely had a person as a hole monitor on board a ship whether new or repair job. However, on repair jobs on ships we have to have a fire watch on the other side of bulkheads as well as in the tank we are doing hot work. Mostly fire watch just sits around with a fire extinguisher and does nothing.
Well, after years of working in welding and paying attention as well as doing my own reading at home and writing emails to manufacturers that create our machines I know a bit about HOW it works but the electronics are sort of a mystery to me. I know some of the power sources I've used have been banks of welding machines hooked up to a much larger DC source. These machines are directly controlled by windings you access with a mechanical turn dial. One way, current goes up, the other way current goes down. Far as I'm concerned they are ok but not my preferred machine. I like Lincoln and Miller machines. It seems like the manufacturers never miss a chance to come out with new machines, various settings for obscure processes we will never use. I prefer simple machines on field jobs as there's no time to learn all the details and they never come to us with a manual.
Mostly on the job I start off with what the last welder set the machine for and the welding equipment they want us to use. Say it's stick welding, I just flip the machine on and do a short weld test and see how it works and if I can weld a straight vertical bead up a plate of steel. This tells me quite a bit about the machine I am running off of and I can adjust it accordingly.
While it's true that at one time a bank of similar machines came out of the factory all calibrated into to the dial so it reads accurately , out on the field the accuracy of those meters on the machine is rarely spot on unless the machine is very new. Things happen. Weathering, rough handling, wear and tear on the internal components, etc, all can change the accuracy of what the meters are telling you so you have to start of either with the previous settings or just pick a ball park setting and adjust from there. Once it's set, you can or should be able to just weld all day. However, a machine that's failing will sometimes have erratic current flows and can't be trusted which can drive a welder nuts until he realizes this and just disconnects and switches to another power source.
I did just look up capacitance and it seems to be related to energy storage so maybe it doesn't apply as no electricity is stored in a welding cable.
I did think my finding on resistance of a very large steel structure to be highly interesting. I just assumed the resistance would be by distance in a straight line and have nothing to do with the mass but apparently, it has everything to do with the mass. I'm thinking that when you ground a machine to a large structure you are essentially charging the entire structure and since it's so massive there is a huge volume of conductive steel to transfer the energy to your welding rod or electrode. The electrons can literally just flow from all around to your electrode so the resistance is barely registering. That's my theory and no ones been able to tell me different.
It's also true that a larger cable has less resistance which is why for some projects, especially air arc gouging you really want heavy cables.
For light welding with say, 3/32 rods they have a rod holder that has a much thinner and more flexible lead on it which you can then connect to your welding cable. If you try to use such a rod holder to weld with larger rods they become overheated and uncomfortable to hold in your hand.
Just a side note, one foreman bitch who was constantly on my ass trying to find fault with me walked up mid shift and told me she needed more weld from me as I was lagging behind. Bullshit, I was doing fine and my work looked great. I had my machine set as fast as I could reasonably weld without burning it up. I was so peeved by her demands I walked over to my power source, turned the settings all the way up and then back to my wire feeder to turn that all the way up. I had to walk back and forth a couple times to balance out the power versus wire feed and then when I had it I went to town burning wire and laying down some reasonable welds but it was not as good as I was welding too fast. Not my problem, it was good enough to pass so there's that. I knew what was going to happen.
About ten minutes later my wire feeder started smoking. I smelt it before I looked up to check and sure enough, smoke was just starting. I kept welding till the dang thing burst into flames and shut down. There now. I can unhook it, go turn it and and return with a working model. Reset to normal welding settings and go back to work. I'm guessing she had seen it happen and she didn't bother me the rest of the shift. The higher settings are only valid if you are actually running a heavier wire, which they do have but you have to replace parts to use it. Those wires are for heavy output on large thick steel and are a pain to use as it leaves the cable in the weld gun very stiff and hard on the hands to maneuver for an entire shift.
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