1.3.4 Effect of Polarity
The electric current used in a welding arc may be either direct current (DC) or alternating current (AC).
Direct current flows constantly in one direction. Alternating current is continually changing direction.
When direct current is used for welding, the welding electrode (consumable or nonconsumable) can be
the positive pole or negative pole in the electrical circuit. The workpiece will have the opposite polarity.
These two arrangements for current flow are called DC electrode positive (DCEP) and DC electrode
negative (DCEN), respectively (Figure 1.9). The type of current selected and its polarity can have a
significant influence on the shape and penetration of the weld bead .