CC vs CV and actual machine output

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I'm trying to get a better understanding of CC and CV, the differences, how each works, why each one is better suited for specific applications, etc. I have searched the net and the forum to gain a basic understanding but I'm having trouble finding more detailed info and I figure some of you guys probably already know where to look. I'm not an engineer or electrician so I prefer something written for my demographic, just a new guy that wants to learn.Also, is there a way to use a DMM to see what the actual output of my machine is on each setting? My Clarke Turbo Weld 150EN has 1/A, 2/3, MIN/MAX switches for output adjustment and I'd like to know more exactly what I'm doing when I flip those switches. Can I just set the DMM to dc voltage then connect the neg lead to the work clamp and the pos lead to the wire and pull the trigger (assuming GMAW, reverse leads for FCAW)?Finally, does the output of the machine vary with fluctuations in the input? I know residential power grids are not exact or perfectly stable but will that noticeably affect welder performance?Thanks for any input, even the "tie your welder to your foot and jump in a lake you idiot noob" ones....I lmfao reading those.NateMiller Syncrowave 250 w/ PC-300 pulserLincoln AC/DC 225/125Clarke TurboWeld 150ENJackson Halo w/ gold lensHuntsman w/ blue lensDoing sanitary stainless tig
Reply:No other takers?O/k I will have a go at answering this.I assume we are talking here about transformer welders ?Constant voltage machines will have varying output voltage as the mains voltage goes up and down in direct proportion.Constant current machines will maintain a fairly constant current regardless of mains voltage variations.Inverter welders use electronic feedback to keep either the CV constant, or the CC constant to whatever  it is set to.The arc welding process needs to be self adjusting to maintain a steady rate of metal transfer, and there are two very different ways to go about doing that.With constant voltage, the wire feeding into the arc determines arc current. As the wire gets closer to the work, the arc current rises and the wire melts away faster. If the wire retreats away from the work, the arc current falls and the wire melts away slower.  It is a self regulating process, where the wire feed speed controls the arc current.Constant current TIG or stick welding is also a self regulating process, but it works quite differently.As the tip/rod gets closer to the work, the voltage falls and total arc power decreases.  But the heat generated right at at both rod and work remains the same right at the arc/metal interface, because the current remains constant.Given that the guy doing the welding can set up the machine properly, and that he can maintain reasonable control over the welding hand piece, both CV and CC can both do the job of creating a self regulating metal transfer process.Cheers,  Tony._________________________________Transmig 310 + Argoshield LightOxy acetyleneOxy propanePrehistoric stick welder_________________________________
Reply:Thanks for the reply Warpspeed. I am talking about transformer welders since that's what both of mine are.I understand the basic principles:CV is used for wirefeed and varies amperageCC is used for stick/tig and varies voltagearc length affects variable in all processesI guess what I'm after is a detailed explanation of how the electrical side of welding machines work including what individual components are doing but its a vague question seeing as how there's many different kinds of machines. I'll keep searching and reading...Miller Syncrowave 250 w/ PC-300 pulserLincoln AC/DC 225/125Clarke TurboWeld 150ENJackson Halo w/ gold lensHuntsman w/ blue lensDoing sanitary stainless tig
Reply:As for actual machine output, I threw my DMM on as described above and came up with a range of 19 to 34 volts. I noticed that changing the wfs directly affected voltage. Lower wfs, lower voltage/ higher wfs, higher voltage.Wfs adjustment changed voltage by up to 3 volts. Is this normal?Miller Syncrowave 250 w/ PC-300 pulserLincoln AC/DC 225/125Clarke TurboWeld 150ENJackson Halo w/ gold lensHuntsman w/ blue lensDoing sanitary stainless tig
Reply:Constant voltage transformer welders just step the mains voltage down with a transformer to the required welding voltage, and the ac voltage is rectified to provide a fairly constant dc output voltage.The voltage will always fall slightly under increasing load.Constant current machines use a special design of transformer that has a magnetic shunt air gap located between primary and secondary windings.  Usually the welder has a plunger or handle of some kind to set the welding current by moving an iron pole piece in or out of the shunt air gap.Too difficult to fully explain here. But basically the magnetic flux generated by the primary winding can take two alternate paths. One is through the secondary winding, the other through the shunt air gap.  With no load, all the flux goes through the secondary, and output voltage is high.  As more load is placed on the welder, the flux divides, and always takes the easiest path, and the output voltage falls.  With a total dead short across the output, just about all of the flux avoids the secondary and is forced through the shunt gap.The magic thing about all this, is that the current in the secondary winding remains fairly constant over a very wide range of applied loads, and the output can be fully shorted without the primary current going dangerously high.Cheers,  Tony._________________________________Transmig 310 + Argoshield LightOxy acetyleneOxy propanePrehistoric stick welder_________________________________
Reply:This link may help you :http://www.esabna.com/EUWeb/AWTC/Lesson1_1.htmparticularly the first 2 chapters. Lincoln and Miller also have books available on their sites covering basic electricity for welders. They can be downloaded or purchased as hard-copies.Note that the voltage of constant-voltage welders is not truly constant, nor is the current of constant-current welders. The variations are responsible for the arc characteristics(e.g. crisp vs. soft arc) of different machines. Voltage measurements need to be made under load to be useful.JohnA few weldersA lot of hammersA whole lot of C-clamps
Reply:Warpspeed, that is the most concise explanation I have heard to this question.  Great job!Lincoln Powermig 255Hypertherm Powermax 45Thermal Arc 161SOxweld 24R OA TorchStill Looking for an Old Round Top Idealarc 250
Reply:Thanks for the replies. I know I'm being difficult but I don't have time/opportunity to discuss this stuff in my weekly welding class. I'll read up using the link and suggestions from Silicon-based. Thanks again guys.Miller Syncrowave 250 w/ PC-300 pulserLincoln AC/DC 225/125Clarke TurboWeld 150ENJackson Halo w/ gold lensHuntsman w/ blue lensDoing sanitary stainless tig
Reply:Originally Posted by Silicon-basedThis link may help you :http://www.esabna.com/EUWeb/AWTC/Lesson1_1.htmJohn
Reply:You can easily measure voltage on any machine by putting one volmeter lead on the work and the other in the electrode holder with the stick or the welding power cable to the wire feeder.  You are only working with 30 volts so you will not do the chicken dance but you definitely can give yourself a good tingle. Amperage is much more difficult since you need a special clamp on DC meter that clamps around the cable and measure the field produced.  If you have meters on the machine it is nice.  Most manuals give you some sort of volt amp curve.  The constant voltage one is more like a flat line. The slope of the volt amp curve changes the characteristics of the arc.  The droop or slope of that volt amp curve is designed into the machine.   Inverter machines work similarly however digital controls create the volt amp curve making the machine much more versatile.
Reply:Originally Posted by lotechmanYou can easily measure voltage on any machine by putting one volmeter lead on the work and the other in the electrode holder with the stick or the welding power cable to the wire feeder.  You are only working with 30 volts so you will not do the chicken dance but you definitely can give yourself a good tingle. Amperage is much more difficult since you need a special clamp on DC meter that clamps around the cable and measure the field produced.  If you have meters on the machine it is nice.  Most manuals give you some sort of volt amp curve.  The constant voltage one is more like a flat line. The slope of the volt amp curve changes the characteristics of the arc.  The droop or slope of that volt amp curve is designed into the machine.   Inverter machines work similarly however digital controls create the volt amp curve making the machine much more versatile.
Reply:Originally Posted by hypothecarySo why is output rated in only amps for both types of machines?
Reply:One exercise done by many welding instructors is to hook up a light socket with a 110 volt light bulb.  One side goes to workpiece and one side goes to the electrode holder.  Your open circuit voltage should be under 75 volts and the bulb will glow moderately.   Now strike up an arc and watch the light bulb as you increase or decrease the arc length.  You will clearly see the bulb glow brighter when you pull a longer arc. ( voltage has gone up)  When you go to a tight arc the voltage drops and the bulb will not be as bright.   The light bulb is easier to see for a group of students gathered around the instructor.
Reply:Originally Posted by WarpspeedWith both transformer type CC and CV welders, it is the transformer winding temperature rise that determines the maximum allowable welding current, and maybe the rectifier current rating too, if there is a rectifier.
Reply:Nate, You are a lot like me, trying to get my head around how all this works.And that is good.Understanding what is actually happening is probably a rather important part of welding.I just wish my own welds looked a lot better than they do.Seeing the welds some of the guys here make is a truly humbling experience.Cheers,  Tony._________________________________Transmig 310 + Argoshield LightOxy acetyleneOxy propanePrehistoric stick welder_________________________________
Reply:Think you'll find that an excellent explanation of CV vs CC is covered in the Miller GMAW Handbook.  You may be able to download it from their site under the resources tab.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:Originally Posted by WarpspeedSeeing the welds some of the guys here make is a truly humbling experience.
Reply:Originally Posted by SundownIIIThink you'll find that an excellent explanation of CV vs CC is covered in the Miller GMAW Handbook.  You may be able to download it from their site under the resources tab.
Reply:Originally Posted by hypothecaryI'm trying to get a better understanding of CC and CV, the differences, how each works, why each one is better suited for specific applications, etc. I have searched the net and the forum to gain a basic understanding but I'm having trouble finding more detailed info and I figure some of you guys probably already know where to look. I'm not an engineer or electrician so I prefer something written for my demographic, just a new guy that wants to learn.
Reply:Originally Posted by con_fuse9On systems that 'maintain an arc' there is a relationship between shielding gas, and gap that more or less specifies what the voltage must be.  Its actually very similar in your car.  Everyone assumes that when you put a ignition system in that is rated at 40K V, you are getting 40K Volts.   Nothing could be further from the truth.  The reality is the voltage, in a car, is determined by the gap on the spark plug and the air/fuel mixture.  Same with stick and TIG welding.  To put more power in, you must increase the current.  So CC machines will deliver whatever voltage is needed to maintain the arc (note some have what they call open voltage - when the gap is too large, no spark, the maximum voltage).  To control the power, you increase the current.   (not to confuse things too much, but if you increase the gap, the power goes up as well).