Electrical Power for Arc Welding 241

“Electrical Power for Arc Welding” explains the basic principles of electricity and the effect that electricity has on arc welding processes. Electricity travels in closed circuits. A basic circuit consists of a source, path, load, and control. Current is the flow of electricity. Voltage is the force that pushes current through a circuit. Resistance opposes current flow, but also makes it possible for electricity to perform work. Electrical work is called wattage. In welding circuits, the resistance of the arc converts electricity into light and heat, which melts the base metals.

After taking this class, users will have a foundational understanding of electricity, electrical variables, and how electricity is used in arc welding. This will prepare users for welding, since every welder must understand basic electrical concepts to work with the arc and the welding equipment that produces the arc.

Class Details

Class Name:
Electrical Power for Arc Welding 241
Description:
“Electrical Power for Arc Welding” explains the basic principles of electricity and the effect that electricity has on arc welding processes. Electricity travels in closed circuits. A basic circuit consists of a source, path, load, and control. Current is the flow of electricity. Voltage is the force that pushes current through a circuit. Resistance opposes current flow, but also makes it possible for electricity to perform work. Electrical work is called wattage. In welding circuits, the resistance of the arc converts electricity into light and heat, which melts the base metals.

After taking this class, users will have a foundational understanding of electricity, electrical variables, and how electricity is used in arc welding. This will prepare users for welding, since every welder must understand basic electrical concepts to work with the arc and the welding equipment that produces the arc.
Version:
2.0
Difficulty:
Intermediate
Number of Lessons:
21
Related 1.0 Class:
Electrical Power for Arc Welding 140

Class Outline

  • Electricity
  • Circuits
  • Current
  • Voltage
  • Resistance
  • Ohm’s Law
  • Electrical Variables Review
  • Direct Current and Alternating Current
  • Uses of DC and AC
  • Polarity
  • Polarity in Action
  • Arc Blow
  • Constant Current and Constant Voltage
  • Constant Current and Constant Voltage: in Action
  • Power Characteristics Review
  • Power Sources
  • Power Conversion
  • Grounding
  • Electrical Safety
  • Inspection and Troubleshooting
  • Power Sources and Electrical Safety Review

Objectives

  • Describe electricity.
  • Describe the components of an arc welding circuit.
  • Describe current in arc welding.
  • Describe voltage in arc welding.
  • Describe resistance in arc welding.
  • Explain the relationships between current, voltage, and resistance.
  • Distinguish between direct current and alternating current.
  • List common uses of AC and DC power.
  • Distinguish between DCEN polarity and DCEP polarity.
  • Describe arc blow.
  • Contrast constant current and constant voltage power.
  • Describe arc welding power sources.
  • Explain power conversion for arc welding.
  • Describe grounding in arc welding.
  • Describe electrical safety hazards and precautions for arc welding.
  • Describe inspection and troubleshooting practices for arc welding equipment.

Job Roles

Certifications

Glossary

Vocabulary Term Definition
AC Alternating current. Electricity that flows in opposite directions at different times. AC switches direction 60 times per second, or 60 hertz, in the U.S.
alternating current AC. Electricity that flows in opposite directions at different times. Alternating current switches direction 60 times per second, or 60 hertz, in the U.S.
ammeters A device that measures current in an electrical circuit. Ammeters are sometimes built in to welding power sources.
amperes A. The unit used to measure current or amperage. Amperes are also called amps.
arc The area in which electricity transfers from the electrode to the workpiece. The arc generates the heat that melts the base metals.
arc blow A condition that occurs when the arc does not follow its intended path from the electrode to the workpiece. Arc blow can cause poor quality weld beads.
arc length The distance that electricity must travel from the tip of the electrode to the weld puddle. Arc length may depend on voltage.
arc welding A fusion welding process that uses electricity to generate the heat needed to melt base and filler metals. Arc welding is the most commonly used welding process.
atoms A tiny particle that makes up all materials. Atoms are the smallest distinguishable units of an element that retain the element's characteristics.
base metals A metal to be welded to form a joint. Base metals' characteristics can greatly influence the strength of the final joint.
beads The end product of a joint that has been welded. Bead formation depends on the movement of the electrode.
CC Constant current. Electrical power in which current varies only slightly with changes in voltage. CC power is often used in shielded metal arc welding and gas tungsten arc welding.
circuit breakers A device that detects excess current to prevent overheating in a circuit. A circuit breaker often contains a bimetallic strip that bends and trips a switch to open a circuit.
circuits A controlled path through which electricity flows. Circuits consist of a source, path, load, and control.
compressed air Air that has been forced into a small space at high pressure. Compressed air is often used to clean electronics.
conductor A material that allows for the flow of electricity. Conductors are typically metals.
constant current CC. Electrical power in which current varies only slightly with changes in voltage. Constant current power is often used in shielded metal arc welding and gas tungsten arc welding.
constant voltage CV. Electrical power in which voltage varies only slightly with changes in current. Constant voltage power is often used for gas metal arc welding and flux-cored arc welding.
consumable electrode A device that conducts electricity from the contact tip of the welding gun to the arc and melts into the weld as a filler metal. Consumable electrodes are used in GMAW and FCAW.
current I. The amount of electricity flowing in a circuit. Current is measured in amperes.
current output The maximum amount of current that a given power source can provide. Current output helps determine how much heat a power source can generate.
CV Constant voltage. Electrical power in which voltage varies only slightly with changes in current. CV power is often used for gas metal arc welding and flux-cored arc welding.
DC Direct current. Electricity that flows in one direction. DC is typically used for GMAW and FCAW.
DC electrode negative DCEN. Current that always flows in one continuous direction with straight polarity. With DC electrode negative polarity, electricity flows from the negative electrode to the positive workpiece.
DC electrode positive DCEP. Current that always flows in one continuous direction with reverse polarity. With DC electrode positive polarity, electricity flows from the negative workpiece to the positive electrode.
DCEN DC electrode negative. Current that always flows in one continuous direction with straight polarity. With DC electrode negative polarity, electricity flows from the negative electrode to the positive workpiece.
DCEP DC electrode positive. Current that always flows in one continuous direction with reverse polarity. With DC electrode positive polarity, electricity flows from the negative workpiece to the positive electrode.
deposition rates The rate at which filler metal melts off the electrode into the weld puddle. Deposition rates can be measured in pounds per hour or in grams per minute.
direct current DC. Electricity that flows in one direction. Direct current is typically used for GMAW and FCAW.
directly proportional A relationship in which one number increases or decreases at the same rate and in the same ratio as another number. Directly proportional is the opposite of inversely proportional.
duty cycle The amount of time in a ten-minute period that an electrical device can operate without overheating. Duty cycles are given as a percentage of the ten-minute period.
electric shocks The flow of electricity through the body. Electric shock can be fatal.
electrical box A metal cabinet in a building where power from the electrical distribution system enters and is distributed throughout the building. The electrical box connects to every circuit and device in the building.
electrical burn A burn caused by the flow of electrical current through tissue or bone. Electrical burns may occur when handling wiring or electrical equipment that has been improperly maintained.
electricity A form of energy created by the movement of electrons. Electricity can be converted into light, heat, or motion.
electrode A device that conducts electricity to the arc in arc welding. Electrodes may also serve as filler metal.
electrode cable The path used in arc welding to conduct electricity between the power source and the electrode. The electrode cable must be in good condition and installed correctly to prevent injury.
electrode holders An insulated handle that clamps onto an electrode. The electrode holder must be dry and in good condition.
electromotive force The electrical force or pressure that causes current to flow in a circuit. Electromotive force is also called voltage.
electrons A negatively charged particle that orbits the nucleus of an atom. Electrons flowing between atoms creates electricity.
energy efficient Having an energy output that is close to the total energy supplied. Energy efficient devices do work using smaller amounts of electricity, which costs less.
faults A dangerous electrical condition that prevents current from completing its circuited as intended. Electrical faults include short circuits and open circuits.
FCAW Flux-cored arc welding. An arc welding process that uses a continuously fed consumable electrode that contains flux at its core. FCAW is either a semi-automatic or automatic process.
filler metal Metal deposited into the weld joint in fusion welding. Filler metal adds to the strength and mass of the welded joint.
flat position The welding position in which the electrode is positioned directly above the joint. Flat-position welding situates the face of the weld horizontally.
flux-cored arc welding FCAW. An arc welding process that uses a continuously fed consumable electrode that contains flux at its core. Flux-cored arc welding is either a semi-automatic or automatic process.
formula A general fact or principle that is expressed mathematically. Formulas represent known equations using letters, numbers, and/or symbols.
gas metal arc welding GMAW. An arc welding process in which a bare wire electrode and inert shielding gas are fed to the weld through a welding gun. Gas metal arc welding is also referred to as MIG or MAG welding.
gas tungsten arc welding GTAW. A very precise arc welding process that uses a nonconsumable tungsten electrode. Gas tungsten arc welding is also referred to as TIG welding.
GMAW Gas metal arc welding. An arc welding process in which a bare wire electrode and inert shielding gas are fed to the weld through a welding gun. GMAW is also referred to as MIG or MAG welding.
grounding A means of providing a safe alternate return path for current that automatically disconnects power if a fault prevents current from flowing like normal. Grounding protects the electrical system and substantially reduces the risk of electric shock.
grounding conductor The wire that provides a low-resistance path to ground for fault currents. Grounding conductors are usually bare copper or covered with green insulation.
grounding pin The longest metal prong of a typical electrical plug. The grounding pin connects to a grounding conductor in the power system when plugged into an outlet.
heat distortion An undesirable physical change in a material due to excessive temperature changes. Heat distortion may be caused by excessive current.
hot wire The wire that provides power to an electrical device or load. The hot wire is usually covered with black insulation.
incomplete fusion The lack of complete integration between the weld metal and base metal or adjoining weld beads. Incomplete fusion can create gaps, which may lead to cracks and joint failure.
insulation Material that resists the flow of electricity. Insulation can prevent electric shock when used properly.
insulators A material that resists the flow of electricity. Insulators include rubber and plastic.
inversely proportional A relationship in which one number either increases as another number decreases or decreases as another number increases. Inversely proportional is the opposite of directly proportional.
inverter An energy-efficient welding power source. Inverters are smaller than traditional power sources, but they have more electrical power.
load A device in a circuit that converts electricity into another form of energy, such as heat, light, or motion. The load in an arc welding circuit is the arc.
low-carbon steel A carbon steel that contains less than 0.30% carbon. Low-carbon steel is the most commonly welded metal.
magnetic field The area in and around an energized conductor in which a magnetic force exists. Magnetic fields exhibit the powers of attraction and repulsion.
negative An electric charge with a surplus of electrons. A negative charge is symbolized by a minus sign (-).
neutral wire The wire that conducts power back to its source and completes the circuit. The neutral wire is usually covered with white insulation.
neutrons A particle that has no charge. Neutrons are located in the nucleus of an atom.
nonferrous Metal that does not contain iron. Nonferrous metals are more difficult to weld than ferrous metals.
Ohm’s Law The universal truth that describes the relationship between voltage, current, and resistance. Ohm's Law states that one volt equals one amp times one ohm.
ohms Ω. The unit used to measure electrical resistance. One ohm is equal to one amp divided by one volt.
out-of-position Any welding position that is not classified or categorized. Out-of-position welding often uses electrodes that have smaller diameters to prevent spillage.
overhead position The welding position in which welding that is performed from the underside of a joint. Overhead-position welding requires extra safety precautions.
path A conductor that directs electricity in a circuit. The path used for welding is often copper wire.
penetration The depth to which the arc heat can melt the joint below the surface of the base metals. Penetration partially depends on the amount of current.
personal protective equipment PPE. Safety equipment that workers wear or use to prevent injury in the workplace. Personal protective equipment includes welding helmets, long gloves, and safety glasses.
polarity Having two oppositely charged poles, one positive and one negative. Polarity determines the direction in which current flows.
pole One end of a magnet or axis. Poles are either negative or positive.
porosity The appearance of tiny holes on a weld bead as a result of trapped gas bubbles. Porosity can weaken a weld.
positive An electric charge with a shortage of electrons. A positive charge is symbolized by a plus sign (+).
power source The device that provides the electricity needed to perform arc welding. The power source is energized by the input voltage supply.
proportional Having a constant ratio or relationship. Proportional values change in order to maintain the same ratio.
protons A positively charged particle. Protons are located in the nucleus of an atom.
reactor A device used in an electrical circuit to stabilize and increase the current of electrical power. Reactors adjust current to suitable levels for arc welding.
rectifier A device used in an electrical circuit to convert AC power to DC power. Rectifiers allow electrical current to flow in only one direction.
resistance R. The opposition to electrical current flow. Resistance is measured in ohms (Ω).
shielded metal arc welding SMAW. An arc welding process that uses a flux-coated rod. Shielded metal arc welding is also referred to as manual or stick welding.
short circuiting The condition in which current takes a shorter, unintended path between two conductors. Short circuiting causes excess current flow.
slag Cooled flux that forms on top of the weld bead and must be chipped off. Slag occurs with welding processes that use flux.
source The device that provides electrical power to a circuit. The source in an arc welding circuit is the power source.
spatter Liquid metal droplets expelled from the welding process. Spatter can leave undesirable particles of metal on a workpiece surface.
thermal contact burns A burn caused by fire or extreme heat. Thermal contact burns can be caused by faulty electrical equipment.
torches A tool used to generate the flame or arc for welding. Torches hold the electrode for arc welding.
transformer A device used in an electrical circuit to reduce the voltage of incoming electrical power. Transformers lower the voltage to suitable levels for arc welding.
travel speeds The rate at which an electrode moves along a joint to make a weld. Travel speed determines the size of the weld bead.
trip To automatically open a circuit to prevent damage and injury. Tripped circuit breakers indicate problems in electrical circuits.
undercut A groove melted into the base metal at the weld toe or root that is left unfilled by weld metal. Undercut concentrates stress on the weld and can weaken it.
vaporize To transform into a gas. Vaporization may occur due to the application of heat.
voltage E. The electrical force or pressure that causes current to flow in a circuit. Voltage is also called electromotive force and is measured in volts.
voltmeters A device that measures the voltage in an electrical circuit. Voltmeters are sometimes built in to welding power sources.
volts V. The unit used to measure voltage. Volts indicate the electromotive force or voltage.
weld puddle The small area of molten metal that forms during welding. Weld puddles are also called weld pools, molten pools, and molten puddles.
welding gun A hand-held welding instrument that conducts electricity, guides the electrode, and, in some cases, releases shielding gas. Welding guns are used in some semi-automatic welding processes.
wire feed speed WFS. The rate at which the wire electrode is fed through the welding gun. Wire feed speed is measured in inches per minute or millimeters per minute.
work The result of a force applied to an object and the distance through which the force is applied. Work is equal to force multiplied by distance.
work cable The path used in arc welding to conduct electricity between the power source and the workpiece. The work cable must be in good condition and installed correctly to prevent injury.
workpiece The part being welded. A workpiece consists of the base metals in a welding operation.