Saf-Fro PRESTOTIG 200 AC/DC, Operator'S Manual, Page: 22 / 436

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Note E . When AUTO is selected, the starting parameters
are automatically recalled based on the set current
adjustable by main knob in the front panel. Diameter of
the electrode is automatically recalled based on the
following table.
Table 9
User dialed weld I
(AMP)
Tungsten diameter
<=200 and > 25 2.4 mm
<=25 and > 7 1.6 mm
<=7 1 mm
Note F : When ADV option is enabled, the user can create
his personal starting setting according to “TIG AC starting
parameters”).
Note G : This option is accessible only when a specific
diameter is selected. When DIA = AUTO or DIA = ADV,
that option is not visible and the default starting
parameters of green (GRN) electrode are recaled.
WAVE-FORM selection
With this option is possibile to select between four
different waveforms:

“Soft” shape: to have a nice balance between a
focused Arc and low noise.

“Fast” shape: to have more focused arc.

“Sin” Wave shape: comparable with older conventional
machines, not very concentrated but very soft.

“Triangle” shape: to reduce the amount of heat
delivered to the workpiece.
Default setting: SQRE
Tungsten Size and Type
In order to ensure the maximum performance and arc
striking reliability the operating parameters of the machine
are automatically adjusted to the type and size of the
tungsten electrode in use. Selecting the appropriate
diameter of the electrode, automatically a recorder set of
parameter is recalled to assure in AC mode a good
striking.
Other then recalled the specific starting parameters
selecting the electrode diameter it is also fixed the
minimum allowable current.
Table 10
Tungsten diameter Min AMP
3.2 mm 20
2.4 mm 10
1.6 mm 7
< 1 mm 2
For AC welding advanced users is present the possibility
to modify the AC starting parameters
Tig AC starting parameters
The unit is delivered not allowing to the user to change
starting parameters: for default option “Tig starting
parameters”, from now on TSTR, is selected in AUTO.
When AUTO is selected for TSTR option, the value of the
4 parameters settable (SCRT, STME, SSLP and PCRT)
and polarity (EP) are stored in unit and can be modified by
the user.
Following picture show the meaning of the parameter for a
local hand working. The ramp in SSLP time ends when
STRT current level is reached: if STRT is lower than
PCRT, the level will be PCRT.
Note: when PCRT is set in the range above, the minimun
current delivered by the unit is PCRT level
The starting sequence changes also if the foot paddle is
present: in fact taking care of the STRT level is not
settable, the level at the end of the SSLP ramp is the level
from the footpaddle or the PCRT level.
NOTE: the setting parameters stored assure the striking
of the arc when correct electode (diameter and colour)
has been correctly selected.
In order to allow maximum flexibility to advanced users
that need complete control over the welding process, the
AC starting parameters can be modified by selecting
MANL for the TSTR (Tig Starting Parameters) option in
Menu C.
User can change polarity,