Download GMAW Power Sources

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Rational
In order to have any electric arc welding process at a high level, the
operator should have a base understanding of the type of power source
that is being used to drive the welding process.
Power Source Output
All power sources used to perform the GMAW and FCAW process are
of the Constant Voltage or Constant Potential output type.
Simply stated, constant voltage output sources are designed to deliver a
set amount of delivered voltage during the welding process in an effort
to maintain the welding arc.
Although all constant voltage output welding power sources are
capable of delivering large surges of welding current (amperage), the
output voltage remains constant.
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Given their design, constant voltage power sources used to perform the
GMAW process are often referred to as having a “self regulating”
welding arc.
In order to maintain this self regulating arc, the following five items are
necessary:
 The proper voltage setting for a given type and size electrode.
 Current going through the electrode (a good ground).
 Appropriate wire feed speed to continuously replace melted
electrode wire.
 A proportional burn-off rate.
 Welding action proportional to the welding (arc) voltage.
Power Source Types
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There are three basic types of welding power sources used to
provide constant current voltage welding output.
Transformer-rectifiers
 This type of welding power source uses a transformer to step down the
AC line power voltage to AC welding voltage and utilizes a rectifier to
change the output current from AC to DC.
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Inverters
 This type of welding source converts the incoming AC power line from
60 hertz to 50 kilohertz.
 The AC welding power is then supplied to a transformer/rectifier unit
to create welding output power.
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Engine Driven Generator
 This type of welding power source uses a internal combustion engine to
drive a generator which creates DC welding power.