Final answer:
In welding with reverse polarity, the electrode is connected to the positive terminal, directing more heat towards the workpiece. This setup, known as DCEP, influences weld penetration and material deposition. AC can also be used in welding for specific applications, like aluminum.
Step-by-step explanation:
With reversed polarity in welding, the welding electrode is connected to the positive terminal of the power supply. This statement can be understood through the general principles of electricity involving the flow of electrons. In typical direct current (DC) circuits, electrons flow from the negative terminal to the positive terminal—an example of this is when a battery moves negative charge through a circuit. This can be seen in illustrations like Figure 19.3, where a battery transfers negative charge from its negative terminal through a device such as a headlight to its positive terminal.
In terms of welding, reverse polarity (also known as DCEP, or Direct Current Electrode Positive) means that the electrode is attached to the positive terminal. The flow of electrons will be towards the electrode, causing more heat to be concentrated at the workpiece as opposed to the electrode itself. This is useful in certain types of welding, like shielded metal arc welding (SMAW), because it affects the deposition rate of the welding material and the penetration of the weld. It's important to note that, although DC is often used in welding, alternative current (AC) can also be employed depending on the welding process. AC power alternates the direction of current flow, which can be advantageous for certain applications like welding aluminum.
To set up a welding circuit for using DC with reverse polarity, you would connect the positive terminal of the voltage source to the electrode and the workpiece to the negative terminal. This configuration aligns with the general understanding that in an electrolytic cell, which operates on similar principles to welding, the anode is the positive terminal relative to the cathode, which is negative. However, this distinction is the opposite in an electrochemical cell, where typically the anode is negative and cathode is positive.