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Arc Welding Power Sources 260

Welding Training

Class Information

Tooling U classes are offered at the beginner, intermediate, and advanced levels. The typical class consists of 12 to 25 lessons and typically requires at least two hours of instruction time.

Class Name:	Arc Welding Power Sources 260
Description:	This class describes different types of arc welding power sources and explains how each power source produces welding power.
Prerequisites:	650115 650120 650140
Difficulty:	Intermediate
Number of Lessons:	19

Class Outline
Objectives What Are Power Sources? Classification of Power Sources Constant Current Power Sources Constant Voltage Power Sources AC Power Sources Alternators Transformers Reactors Types of Reactors Silicon-Controlled Rectifiers DC Power Sources Generators Rectifiers Inverters Power Factor Energy Efficiency Electrical Safety Summary

Class Objectives

Define power source.
Describe how welding power sources are classified.
Describe characteristics of constant current power sources.
Describe characteristics of constant voltage power sources.
Describe common uses for AC.
Describe how an alternator works.
List the components of a transformer.
Describe how a reactor works.
List types of reactors.
Describe how a silicon-controlled rectifier works.
Describe common uses for DC.
Describe how a generator works.
Describe how a rectifier works.
Describe how an inverter works.
Explain the importance of power factor.
Explain the importance of energy efficiency.
Describe the electrical risks associated with power sources.

Class Vocabulary
AC	The abbreviation for alternating current.
alternating current	Current that regularly reverses the direction of its flow. Gas tungsten arc welding (GTAW) often uses AC.
alternator	A device that generates alternating current through the use of a mechanical device like an engine or a motor.
amperage	A measurement that indicates the amount of current flowing in a circuit. Amperage is measured in amperes.
anode	An electrical terminal that usually carries a positive charge. In welding, an SCR powers on only if the anode is negative.
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 undesirable weld beads.
arc length	The distance the arc stretches from the electrode to the workpiece. Longer arc lengths require more voltage.
armature	A device found in generators that has many separate coils wound around it. When the armature rotates in the generator, it creates a magnetic field, which produces direct current.
brush	A device found inside a generator that is used only in pairs. One brush carries a negative charge, and the other carries a positive charge. The brushes touch the current-carrying commutator.
cathode	An electrical terminal that usually carries a negative charge. In welding, an SCR powers on only if the cathode is positive.
CC welder	An abbreviation for a constant current welder.
choke	Another name for inductance coil or stabilizer.
circuit	A controlled path for electricity. Arc welding requires a closed electrical circuit.
coil	A wound spiral of two or more turns of wire used to conduct current.
commutator	A current-conducting device found inside a generator. Commutators are made of copper and touch one or more pairs of brushes.
constant current	Welding using a current that varies slightly with significant changes in voltage. Constant current, or CC, is often used in shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW).
constant voltage	Welding using a voltage that varies slightly with significant changes in current. Constant voltage, or CV, is often used for gas metal arc welding (GMAW) and flux-cored arc welding (FCAW).
CV welder	An abbreviation for constant voltage welder.
direct current	Current that flows in one continuous direction. Gas metal arc welding (GMAW) and flux-cored arc welding (FCAW) require DC.
droop curve	The type of output slope produced by a constant current welder. Droop curves have a steep slope and are sometimes called droopers.
drooper	The type of output slope produced by a constant current welder. Droopers have a steep slope and are sometimes called droop curves.
duty cycle	The amount of time in a ten-minute period that a welder can perform work without overheating. In the shop, welders with a higher duty cycle are preferred.
electric arc	The area in which electricity jumps from the electrode to the workpiece. The heat generated by the electric arc melts the base metals.
electricity	The energy created by the movement of electrons. Electrical energy can be converted into light, heat, or motion.
electromagnet	A magnet formed from electric current. An electromagnet is typically formed by wrapping several windings of wire around an iron core.
energy efficient	A characteristic of welders that signifies good use of electricity. Energy efficient devices do work using smaller amounts of electricity, which costs less.
field winding	A type of wire that acts as an electromagnet and creates a magnetic field inside a generator.
flux-cored arc welding	An arc welding process that uses a continuously fed consumable electrode that contains flux in a hollowed-out center. It is also referred to as FCAW.
gas metal arc welding	An arc welding process in which a bare wire electrode and inert or active shielding gas is fed to the weld through a welding gun. It is also referred to as GMAW or MIG welding.
gas tungsten arc welding	A very precise arc welding process that uses a nonconsumable tungsten electrode. It is also referred to as GTAW or TIG welding.
gate	The switch that powers a silicon-controlled rectifier. A gate only allows the SCR to switch on if the current is flowing in the proper direction.
generator	A device that generates direct current through the use of a mechanical device like an engine or a motor.
half cycle	Half of one complete cycle. A half cycle of a transformer occurs when the secondary coil induces current. A full cycle occurs when both the primary coil and secondary coil induce current.
Hertz	A unit of measurement indicating a single cycle of alternating current.
high-deposition electrode	An electrode that deposits a large amount of filler metal into a weld joint.
hot start	A feature on some welders that allows welding to begin with very high settings. Hot starts prevent sticking the electrode.
IGBT	The abbreviation for insulated gate bipolar transistor.
inductance coil	An electrical device that smoothes out the rippled path of DC power after it passes through the rectifier. The inductance coil is sometimes called the choke or stabilizer.
insulated gate bipolar transistor	A type of filter used in inverter-based power sources that elevates incoming power to frequencies as high as 20,000 Hz. Insulated gate bipolar transistors are often referred to by their abbreviation, IGBT.
inverter	An arc welding power source that operates at very high frequencies and is much more energy efficient than transformer-based machines.
laminated iron core	The device found in a transformer that is located in the center of the primary and secondary winding. The laminated iron core ensures that current does not stray from its intended flow.
low-hydrogen electrode	An electrode that is used to weld specialized materials that are susceptible to cracking.
magnetic field	The space in which a magnetic force exists.
movable iron reactor	A type of reactor that controls transformer output by moving a piece of iron between the windings that remain stationary.
nonferrous electrode	An electrode that does not contain iron. Nonferrous electrodes are used to weld nonferrous metals.
output	The type of power that the welder produces. Forms of output include direct current (DC), alternating current (AC), constant current (CC), and constant voltage (CV).
output slope	The name given for the slope on a static volt-ampere curve.
polarity	The direction of current flow in a direct current (DC) circuit.
power factor	The relationship between the amount of power a welder draws from the power company and the amount of power it returns to the power company. Ideally, a welder has a power factor of 1, or 100%.
power source	A device that generates electricity. Arc welder power sources can be plugged into a wall outlet, or they can generate electricity through the use of a mechanical device like a motor or generator.
primary voltage shock	An electrical shock from 120-480 volts that occurs in arc welding from touching a lead inside a switched-on welder and then touching the welder case or other grounded metal at the same time.
primary winding	The first winding that current passes through in a transformer. The primary winding contains multiple thin wires that are wrapped into a coil.
pulse welding	A type of welding that uses a transfer method in which as little as one droplet of metal forms on the end of the electrode at a time. Pulse welding requires the highest welder settings.
reactor	An electrical device that smoothes out transformer output and adjusts amperage according to the desired settings on the welder.
rectifier	An electrical device that converts AC power to DC power. Rectifiers allow current to flow in one direction only.
resistance	The opposition to current flow. Electricity flows in the path of least resistance.
reverse polarity	Current in arc welding that flows from a negative workpiece to a positive electrode.
rotor	A device found in alternators that contains many windings of wires. When the rotor rotates inside the alternator, it creates a magnetic field, which produces alternating current.
SCR	The abbreviation used for silicon-controlled rectifier.
secondary voltage shock	An electrical shock from 60-100 volts that occurs in arc welding from touching the electrode while another part of the body touches the workpiece.
secondary winding	The second winding that current passes through in a transformer. The secondary winding contains fewer, but thicker wires that are wrapped into a coil.
self-regulating system	A characteristic of constant voltage welders. Constant current welders are considered self-regulating systems because a change in arc length automatically adjusts the electrode melting rate.
shielded metal arc welding	An arc welding process that uses a flux-coated consumable rod electrode. It is also referred to as SMAW or stick welding.
silicon-controlled rectifier	A type of reactor that controls transformer output by allowing current to flow in one direction only. Silicon-controlled rectifiers are often referred to as SCRs.
slope	The angle of a line that appears when comparing two variables on a graph.
stabilizer	Another name for inductance coil or choke.
stainless steel	A type of steel that contains more than 15% chromium and exhibits excellent corrosion resistance.
static volt-ampere curve	A type of graph used to chart a welder's voltage output versus its amperage output in a given time period.
step control	A means of controlling transformer output by selecting the amount of windings to use. Step control is not preferred, because it is not a smooth, continuous control of transformer output.
step-down transformer	A type of transformer used for welding power sources that converts high-voltage, low-amperage industrial power to low-voltage, high-amperage power.
step-up transformer	A type of transformer that increases voltage. Arc welding does not use step-up transformers.
straight polarity	Current in arc welding that flows from a negative electrode to a positive workpiece.
tap reactor	A type of reactor that controls transformer output by selecting the number of windings to use.
transformer	An electrical device that adjusts voltage.
voltage	The electrical force or pressure that causes current to flow in a circuit. Voltage is measured in volts.
watt	A unit of measurement that indicates the amount of electrical power in a circuit.
weldor	A term sometimes used to refer to the person who welds.
winding	Wire wrapped around a core or into a coil that is used to conduct current. The more windings used in a power source, the more amperage the power source can generate.