PATON
VDI-SERIES PRO
DC MMA/TIG/MIG/MAG
-15-
3.3. INCREASED – CURRENT ARC STARTING
The advantages ensured by the increased-current arc starting function are the
following:
•
Improved arc starting even when low-quality electrodes are used
•
Better joint penetration during arc starting period and, as a result, the lower number
of defects associated with incomplete joint penetration.
•
Prevention of slag inclusions
Manual adjustment operations:
allow the minimum arc starting current to be set in
order to decrease power consumption at the stage of arc starting. As a result, the welding
arc can be started at the minimum power supply voltage, but in this case, the arc quality
characteristics at the stage of arc starting are deteriorated, as the welding unit functions
as an arc-welding transformer. Nevertheless, in some conditions, this method of arc
starting is the only possible one. The welding current may be increased in order to
improve the conditions for arc starting (when the welding unit is connected to a reliable
power supply system), but the increased current can cause burn-out when welding thin
parts. Therefore, it is recommended to set the minimum arc starting current.
What is achieved by:
During the short time interval of arc starting, the welding current increases by 40 % of
the welding current set by default.
Example:
Electrode diameter is 3 mm.
Set welding current is 90 A.
The current at the increased-current arc starting stage is 90 + (0.40
90) =126 A.
The additional adjustment operations
allow both the arc starting current
[H.St]
and the
arc staring period
[t.HS]
to be varied. Do not set the increased values of these parameters
if such increased values are not required, because the operation of the welding unit and
reliable arc starting in these conditions are possible only if the welding unit is connected
to a high-power system.
The procedure for changing the values of the operational parameters of the welding unit for the
current welding process is described in Section 6.1.
