Output Limitations; Dc Tig Welding; Welding Polarity - Lincoln Electric invertec v205-t Operator's Manual

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OUTPUT LIMITATIONS

The maximum output current is derated in two situa-
tions; alternate AC Wave Forms and elevated AC
Frequencies.
• Alternate AC Wave Forms (Set Set Up Menu)
Square 200 amps max. output
Sinusoidal 150 amps max. output
Triangular 120 amps max output
• Elevated AC Frequencies
Above 85Hz (AC output) the square wave out-
put is limited to 170 amps. Elevated AC
Frequencies do not effect the output of
Sinusoidal and Triangular Waveforms.
These derated values have been programmed into the
Invertec V205-T AC/DC to ensure reliable operation.

DC TIG WELDING

(see FIGURE B.3)
The TIG (Tungsten lnert Gas) welding process is
based on the presence of an electric arc between a
non-consumable electrode (pure or alloyed tungsten
with an approximate melting temperature of 3370°C)
and the workpiece. An inert gas (argon) atmosphere
protects the weld pool.
To avoid dangerous inclusions of tungsten in the joint,
the electrode should not contact the workpiece. For
this reason the arc is started through a Hi. Freq. gen-
erator.
For situations requiring no Hi. Freq., Touch Start Tig
reduces the short-circuit current to keep tungsten
inclusions to the minimum.
To improve weld bead quality at the end of the weld it
is important to carefully control the downslope of cur-
rent and ensure proper gas coverage over the weld.
FIGURE B.3
1) Workpiece
2) F iller material
3) Non-consumable electrode 7 ) lnert gas (argon)
4) Torch
OPERATION
5) Flowmeter
6) Pressure reducer
8) Power source
V205-T AC/DC TIG

WELDING POLARITY

D.C.S.P. (Direct Current Straight Polarity)
(see FIGURE B.4)
While Welding, there is a continuous flow of electrons
from the electrode to the workpiece.
This is the most used polarity, ensuring limited wear of
the electrode, since the majority of the heat concen-
trates on the anode (workpiece). Narrow and deep
welds are obtained with high travel speeds.
Most materials, with the exception of aluminum and
magnesium, are welded with this polarity.
FIGURE B.4
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