5 OPERATION
0463 605 001
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© ESAB AB 2018
5.2.2
For TIG process
For TIG process (requires optional TIG accessories: see "ACCESSORIES" chapter), connect
the TIG torch power cable to the negative [-] terminal (7). Connect the gas inlet nut on the
TIG torch to the gas outlet connector (4) located on the front of the power source. Connect
the gas inlet nut (12), on rear panel, to a regulated shielding gas supply. Connect the work
return lead to the return-cable terminal (9). Connect the torch connector to the Euro-torch
connection (6).
5.3
Polarity change
The unit’s power source is delivered with the polarity changeover cable connected to the
positive terminal. Some wires, e.g. self-shielded cored wires, are recommended to be welded
with negative polarity. Negative polarity means that the polarity changeover cable is
connected to the negative terminal and the return cable remains as the connection for the
torch return-cable.
Check the recommended polarity for the welding wire you want to use. Refer to
electrode packaging for information relating to the correct electrode polarity. The
polarity can be changed by moving the polarity changeover cable to suit the
applicable welding process.
5.4
Shielding gas
The choice of suitable shielding gas depends on the material and weld process. Typically, in
MIG/MAG process, mild steel is welded with mixed gas (Ar + CO
2
) or 100% carbon dioxide
(CO
2
). Stainless steel can be welded with mixed gas (Ar + CO
2
) or trimix (He + Ar + CO
2
).
Aluminum and silicon bronze use pure argon gas (Ar). In the sMIG mode (see "sMIG mode"
section in the "CONTROL PANEL" chapter), the optimal welding arc with the gas used will be
automatically set. In TIG process 100% argon is typically used.
5.5
Volt-ampere curves
The curves below show the maximum voltage and amperage output capabilities of the power
source for three common welding process settings. Other settings result in curves that fall
between these curves.
A
= Welding current (AMPS),
V
= Output voltage
Summary of Contents for EMP 255ic
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