5.1 Welding Power
David Ridge
Components of Electricity
Disclaimer: The purpose of this section is to teach you about electricity only inasmuch as it applies to welding. The subject of electricity and all the ways we use it is a much broader topic and not the focus of this chapter. Every effort will be made to keep the discussion narrowly focused on how electricity is used to weld.
To start, all matter is made up of atoms. Atoms have three main parts: protons, neutrons, and electrons. The protons and neutrons of an atom are clustered together in a little ball at the center of the atom called the nucleus. The electrons of an atom circle the nucleus in tiny orbits. Any given material is determined by the number of protons, neutrons, and electrons in the atoms that it’s composed of.
Each of the three parts of an atom has a different electrical charge. Protons have a positive electrical charge, neutrons have no electrical charge, and electrons have a negative electrical charge. If an atom has more protons than electrons, then the overall electrical charge of the atom is positive, and vice versa.
The atoms in certain materials have weak bonds with their electrons, which allows the electrons to travel to and from the other atoms in the material. These materials are called conductors, and the more readily a conductor allows the movement of electrons between atoms, the better of a conductor it is. This is important because electricity, also called an electric current, can be described as the movement, or flow, of electrons from one atom to another in a conductor.
Some common conductors include iron (atomic symbol Fe) and copper (atomic symbol Cu).
There are some materials,e called insulators, that resist the flow of electricity, meaning that they do not allow electricity to flow through them very well, or even at all in some cases. Insulators are just as important to how we use electricity as conductors, and you will often find conductors and insulators used together. For example, a power cable is a copper conductor wrapped in a rubber insulator for safety. This keeps anyone from coming in contact with a dangerous electric current.
When talking about the flow of electricity, we say that an electric current flows in a circuit. This means that the electrons are flowing in a cyclical path. In fact, without a complete circuit to follow, electrons won’t flow at all. When electricity is flowing in a completed circuit, we say that the circuit is “closed.” When there is a break in the circuit (and electricity isn’t flowing), we say that the circuit is “open.”
There are a number of terms that describe and measure the flow of electricity. The most common for welders to use and hear are voltage, amperage, wattage, and ohms. Of these terms, voltage, and amperage will be the most important for you to understand as a welder because welding machine settings are based on these.
Volts/Voltage
A volt is a measure of electrical “pressure.” If we think about electricity flo