Welding polarity can be confusing to someone that’s just learning how to weld. There are several different terms used to describe it and different welding processes and electrodes may require different settings. It may not seem to make much sense at first, but if you understand the basics it should become more intuitive. Hopefully this will help to enlighten you a little bit.
It should be noted that this pertains to DC welding only. AC welding switches polarity 60 times per second and can be thought of as both positive and negative. DC on the other hand can either be positive or negative polarity. An analogy is to think of a welding circuit as a basic DC electrical circuit-The welding machine as the voltage source and the welding arc as the resistance. In a circuit like this, current will flow from the negative side of the voltage source, through the resistor, and then to the positive side of the voltage source. This is exactly how a welding circuit works. Current flows from the negative side of the welder, through the arc, and then back to the positive side of the welder. A side effect of this is that more heat goes in the direction of current flow–Approximately 2/3rds of the heat will go to the positive side of the circuit. So if you’ve got your electrode hooked up to the negative terminal of the welder, (DCEN-DC electrode negative), approximately 2/3rds of the heat will be put into the workpiece.
In the early days of welding it was common to designate DCEN as straight polarity, and DCEP as reverse polarity. Just remember:
DCEN = DCSP=DC straight polarity= heat to workpiece
DCEP = DCRP=DC reverse polarity = heat to electrode.
The opposite is true for (DCEP=DC electrode positive), 2/3rds of the heat will be biased towards the electrode.