I have an older machine that I've been playing with. I'm having a little trouble running excel arc 71. The wire should be run dcep, but after welding (per mfg specs) and cutting a few samples the dcen appears much better. The samples were 3/8" t fillets that were cut. The dcep had a slag line running the full length of the root. The dcen was clean. How can I test what my polarity actually is? Or am I missing something really simple?
Hello hogan, a simple method would be to use a multimeter or other DC capable testing device to check the voltage across the output terminals. If you attach the +/red lead to the + output stud and the -/black lead to the - output stud the meter will show the correct OCV and a "+" sign if the polarity is correct on a digital meter, if you have an analog meter it will read the appropriate voltage if the polarity is correct and if it's not it will try to sweep the needle to the far left and bury it against the 0 on the meter. You will also need to trigger the machine to show output or else if it is equipped with a contactor selector switch on the power source you will need to switch this to the on position instead of the remote. Hope this has made sense. Good luck and best regards, Allan
Allan has it...check it with a meter to verify the polarity(he covered both digital and analog).
In this day and age the meeter is the way to go.
An old school method is to strike an arc with carbon electrodes and compair the arc and the shape of the electrode point. Straight polarity makes a smoother arc and maintains the point on the electrode, while reverse polarity gives an eratic arc and blows the point off the electrode. This was the method taught by Hobart Trade School in the '50s.
A fool proof method is to hook up a Tig torch, if you can, (you will need shielding gas, of course) and strike an arc. Set the amperage fairly low, maybe ~75 amps. You will quickly know if you are on DCEN or DCEP. Once you have determined which is which, clearly mark the terminals for future reference.
Suggestion. Try a clamp on multimeter. DC range, ground to negetive output. Most meters have auto polarity functions. Wouldn't recommend an analoge meter if your not sure of the polarity. There is a very good possibility of damaging the needle or blowing out the needle movement all together. The same multimeter may be used to calibrate your weld machine if there is a need to so it does have a dual function.
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