Open circuit voltage...

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I understand what it is. But what is it's significance to the different welding processes? Is there an ideal ocv?Specifically stick welding and the effect on different rods.  Also, Tig.Thanks
Reply:7018 and some other rods just won't run on lower voltage machines. I believe the 7018AC rods were made more for the lower voltage machine more so than running them on AC. I think OSHA limits OCV to around 80 or 90 volts. I sure there's more to it than that.
Reply:ocv is unloaded voltage... the voltage will drop when the arc is struck, or rod shorted.  the AC rods were designed so that the arc could re-ignite when the voltage crossed 0 volts.  My Dynasty has the option for high voltage or low voltage OCV... I have it set on low, which is about 8 volts.  Runs 7018 like a champ.  Dunno what high is for... never used it
Reply:It took me years to figure this one out.  I finally found out when reading the Procedure Handbook of Arc welding by lincoln Electric.   I am eating dinner.  I will find the graph and post a pic when I am done.Good question.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:OCV is the voltage when you're not welding, like hooking a VOM across the stinger and work clamp, welding voltage varies with arc length, short arc low volts, long arc higher voltage.
Reply:OK, I found it.  this shows what different OCV can have to do with welding.As you can see, the lower OCV gives more control to the weldor.  The available amp change for High OCV is 40 amps, and for low OCV is 15 amps.to give credit to the publisher, The procedure handbook of Arc Welding by the James F. Lincoln Are Welding foundation.Last edited by David R; 09-17-2007 at 06:16 PM.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Thanks guys.
Reply:David R I have read that exact page only a few months ago and had completely forgot about it. Thanks for letting me know that I'm loosing it.
Reply:I ran afoul of high open circuit voltage with my small 117 VAC arc welder - see post 'lobotomy of an arc welder' at http://www.weldingweb.com/vbb/showthread.php?t=11143The welder originally had 71 turns of the secondary and an open circuit voltage of ~60 volts.  While welding with Lincoln 7018AC (3/32 rod), the welding voltage was ~33 volts with a current of ~84 amps max.  The high open circuit voltage allowed me (in my inexperience) to maintain quite a long arc - resulting in porous welds that did not stick metal together.I removed 15 turns of wire (down to 56 turns on the secondary) and the open circuit voltage dropped to ~47 volts.  While welding with Lincoln 7018AC (3/32 rod), the welding voltage was ~23 volts with a current of ~105 amps max.  In my case, the lower open circuit voltage was a blessing; it forced me to keep a small gap (else the arc would go out) - that and the higher amps allowed me to make much-much better welds.However, later when I tried to power my twin-rod carbon-arc torch that I used for brazing, the lowered open circuit voltage would not maintain that nice long arc I used to have.Rick V
Reply:Originally Posted by David R As you can see, the lower OCV gives more control to the weldor.  The available amp change for High OCV is 40 amps, and for low OCV is 15 amps..
Reply:The reason I asked the question was because I was looking at purchasing a new power supply for stick and tig.  Somebody mentioned ocv...  I have never really paid much attention to ocv.Anyway, after Tresi mentioned OSHA I did some research.  This may be helpful to sombody.  It is 80 v max ocv.  I am not selling these, they just had the regulations excerpts.http://www.groundfaultsystems.com/There was also an Austrailian site that specified different voltages for different enviromental conditions.  google - ocv welder.
Reply:Ok, here I go. Run an old Lincoln, you can get 5 different arcs at the same amperage by changing the voltage. I can run 1/8 6010 that will blow through plate, or I can click down and run it like butter, both at 100 amps. OCV is what makes the stinger your magic wand, you can effectively change your macines performance by arc length. I have a new Trailblazer, and it's OCV varies per computer board depending on arc length. It is a good machine don't get me wrong, but you just cant dial it in like an old Lincoln. So basicaly if you set the machine on coarse adjustLO, and run the fine on Hi you "dig".If you set the coarse on Hi and run the fine on LO it is like butter.This is the best I can describe it. You really need to run an old machine to see for your self.Last edited by TozziWelding; 09-18-2007 at 07:30 PM.Disclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:Thanks TozziI have an old century.  It has 4 taps for plugging the stinger into the welder.  I assume the different taps have different ocv.  It also has 4 scales corresponding to the taps and recommended rods for each scale/tap.
Reply:I always thought you ran the arc short to keep the puddle cool  According to this Its max available amps at a lower voltage.My invertec v350 pro claims in the instructions that It keeps the amperage the same regardless of arc length.  The instructions for my ranger 250 make a similar claim.  I put an ampmeter on the ranger 250 and ran it at different amps to set my remote for amps and volts because its numbered 1-10.  Set the ranger on 90 amps and vary the arc length all you want, I still get a flat line on the oscope.  It might vary + or - 1 amp.  I never bothered to try it with the V350.  It says you can get good welds even with an unsteady hand. Bob Crow at Lincoln explained it to me after I talked to 12 previous people at lincoln electric.  They answered a lot of my questions, like "What does this arc force knob do?  I looked at the weld voltage on the ocilliscope wile my son welded.  I set the knob differently.  I could see a slight change in wave length.  Its supposed to be pulsed DC at 20, Mhz.  Mine runs at 19 Mhz but that changes with the arc force or inductance knob.  Its been a year since I have done this.   Probably should try it with the v350.I also asked bob about the downhill pipe setting.  He said It is supposed to emulate the exact wave as an SA200.  I have never put my scope on a SA200 or any brushed engine drive.  He said the arc force  knob adjusts slope.Hope this helps.Now I gotta put the scope on the v350. DavidLast edited by David R; 09-18-2007 at 08:54 PM.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:OCV for CV Power supplies is normaly 35 to 45.  CC power supplies is normally70 to 80. welding currents has nothing to do with OCV.
Reply:Originally Posted by TozziWeldingOk, here I go. Run an old Lincoln, you can get 5 different arcs at the same amperage by changing the voltage. I can run 1/8 6010 that will blow through plate, or I can click down and run it like butter, both at 100 amps. OCV is what makes the stinger your magic wand, you can effectively change your macines performance by arc length. I have a new Trailblazer, and it's OCV varies per computer board depending on arc length. It is a good machine don't get me wrong, but you just cant dial it in like an old Lincoln. So basicaly if you set the machine on coarse adjustLO, and run the fine on Hi you "dig".If you set the coarse on Hi and run the fine on LO it is like butter.This is the best I can describe it. You really need to run an old machine to see for your self.
Reply:hmmm.... the longer the arc the less heat reaches the weld since its distributed over a larger distance.  Isnt  there also the question of metal transfer - whats its relation to voltage, current and heat?Last edited by maddog; 10-09-2007 at 02:48 PM.355# Hay Budden3# Hofi HammerPropane ForgeIdealarc TIG 300/300AllStates Oxy Propane torchSmith Little Torch
Reply:Three voltages in welding: Open Circuit Voltage ( when no current is flowing ), Welding voltage ( voltage the power supply puts out) ) and Arc voltage (READ AFTER ALL THE RESISTANCE HAS BEEN USED UP BY THE CABLES AND ETC.)Last edited by weldgault; 10-09-2007 at 10:21 PM.SMAW,GMAW,FCAW,GTAW,SAW,PAC/PAW/OFCand Shielding Gases.  There all here. :