helvi COMPACT 300 Betriebsanleitung Seite 31

to be welded. The length of the tapering will
depend on the diameter of the electrode: with
low current, tapered tip with tapering length
l = 3 x d; with high current, rounded tip with
tapering length l = 1 x d.
The triggering of the arc in TIG may be per-
formed with peaks of high voltage at high fre-
quency; this solution (HF system) does not
require contact between the electrode and
the piece in order to trigger the welding arc.
To trigger the arc without HF the electrode
must come into contact with the piece (Lift
Arc system). The arc trigger mode in TIG is
subject to the type of generator (read the IM-
PORTANT notes below).
The operational phases of the Lift Arc system
are:
• Lightly press the electrode on to the piece
which is to be welded (1).
• Press the torch button. The gas will flow and
the current will pass through the electrode.
• Move the electrode away from the piece,
rotating it so that the nozzle of the torch re-
mains in contact with the piece (2-3).
• The arc has now been established and the
current will reach the level of welding set be-
fore (4).
IMPORTANT
• 305HF generators come with HF; triggering
the electric arc therefore requires no contact
between the electrode and the piece.
• 300 - 300C generators come with the Lift
Arc system; triggering the electric arc there-
fore requires contact between electrode and
the piece.
WARNING: To trigger the electric arc
with the Lift TIG system also with 305HF
generators, follow the instructions be-
low prior to supplying power to the cur-
rent generator:
• Press the torch button. While keeping it
pressed, switch on the inverter.
Fig. 15
Fig. 16
• Release the torch button only after the in-
verter has performed the preliminary checks.
COMPLETING THE TIG SYSTEM
WITH AN AIR COOLED TORCH
• Connect the earth lead to the positive (+)
Dinse socket of the generator (pos. 5) and
the earth clamp to the piece which is to be
welded.
• Connect the power cable of the torch to
the negative (-) Dinse socket of the generator
(pos. 4) and connect the torch button cable to
the three-pole socket on the generator (pos.
7) (pin 1 & 2).
• Connect the gas tube to the "gas connec-
tion" located on the rear panel of the genera-
tor (pos. E) and to the pressure reducer as-
sembled on the suitably fixed cylinder.
(Note: The gas which must be used is pure
argon; for further information on "PROTEC-
TION GAS CONNECTION", please read the
relative paragraph).
• Hold the torch without pushing the trigger;
supply voltage to the generator using the
start/stop (ON/OFF) switch assembled on the
rear panel (pos. A) of the generator (Warning:
The welder will suggest the settings used in
the previous welding).
• Use the button (pos. 14) to select the wel-
ding procedure with the infusible electrode
(TIG).
• Use the button (pos. 15) to select the diffe-
rent welding modes:
(Note: Functions 2T/4T pulsed current and
the up-slope are available only on 305HF ge-
nerators; on 300 - 300C generators it is only
possible to weld in direct current in 2T mode)
• 2 stroke – 2T LED on with fixed light,
• 2 stroke pulsed – 2T LED flashing,
• 4 stroke – 4T LED on with fixed light,
• 4 stroke – 4t LED flashing.
• Press button pos. 16 or 16A (depending on
the generator) to activate the "menu" or "set"
function (depending on the generator) to se-
lect and adjust the values (using knob pos. 2)
of the relative TIG cycle functions.
IMPORTANT: For further information on
parameter functions and regulations du-
ring TIG welding, please read the para-
graph on WELDING PARAMETER CON-
TROL PANEL.
31