voltage (V): the force that causes electrical current to flow in a circuit
amperage (I): the amount (rate) of electrical current flowing through a circuit
resistance (R): causes a backup of electrons and buildup of heat
welding leads: connect the power source to the base metal and electrode
alternating current (AC): current that continually and rapidly reverses because the charge at the power source causes the poles to switch locations. The cycle frequency is 60 hertz in North America and 50 hertz in Europe. Advantages of AC include elimination of problems associated with arc blow, lower amperage when used in SMAW, and the ability to be converted into DC.
direct current (DC): current that flows in one direction through a circuit whose positive and negative poles maintain their positions. Direct current has one of two types of polarity.
reverse polarity synonyms include: direct current reverse polarity (DCRP), DC+ and direct current electrode positive (DCEP). The cable attached to the electrode holder is connected to the positive terminal, and the work clamp is connected to the negative terminal. Electricity flows from the machine to the base metal first, jumps across the gap to the electrode, and flows back to the machine. A majority of heat is concentrated in the part to which the arc is jumping (the electrode).
straight polarity synonyms include: direct current straight polarity (DCSP), DC- and direct current electrode negative (DCEP). The cable attached to the electrode holder is connected to the negative terminal, and the work clamp is connected to the positive terminal. Electricity flows from the machine to the electrode first, jumps across the gap to the base metal, and flows back to the machine.
A majority of heat is concentrated in the part to which the arc is jumping (the base metal).
direct current applications:
SMAW uses DCEP or DCEN or AC (depending on electrode and base metal thickness)
GMAW uses DCEP only
GTAW uses DCEN (except it uses AC for aluminum or magnesium)
