ESAB Aristotig 405 AC/DC, Service Manual

Page: 79 / 92

- 79 -
7.2 SETTING, DC AND AC
Setting of the desired welding current type using the welding current selection switch (22).
7.2.1 DIRECT CURRENT
When DC welding, the electrode (TIG- and electrode welding) is connected to the negative pole
and the return cable to the positive pole.
7.2.2 ALTERNATING CURRENT
Connect as for DC configuration. Two different AC types can be selected using the welding cur-
rent selector (22).
• A square alternating current is distinguished by a stable arc, although, it causes a higher
working noise.
• The sinusoidal type provides the user with an alternating current curve with less noise.
Using the potentiometer AC frequency (19), the frequency is progressively adjustable from 50 up
to 200 Hz. A higher AC frequency results in a more concentrated and a more stable arc.
It is suitable for lower currents and for welding thin plates.
Using the potentiometer AC balance (21), the balance can be varied between positive and nega-
tive half cycles.
A balance shift in the positive direction causes a higher cleaning effect. A shift in the negative di-
rection causes a higher penetration.
8 FORCED INTERRUPTION
When the torch button or the foot operated remote control is activated, but no arc is generated,
the open-circuit voltage is turned off automatically after 2 seconds. It will also turn off, when the
arc is lost.
The arc can be started again by releasing the torch button and activating it again.
This function prevents:
• Uncontrolled arc ignition
• Material damage
• Protective gas leakage
• Accidents