Thermal Arc 201 TS Service Manual page 31

OPERATION
C. TRIGGER Mode Switch (LIFT TIG Mode Only)
2T (Normal) Mode
Press the TIG Torch Trigger Switch or Foot Control and
hold depressed to weld. Release the TIG Torch Trigger
Switch or Foot Control to stop welding. Down Slope
operates in LIFT TIG (GTAW) mode only. While welding
if the TIG Torch Trigger Switch is released, the welding
current ramps down to zero current over a defined period
of time. The time period is determined by the Down Slope
Control Knob (F).
4T (Latch) Mode
This mode of welding is mainly used for long weld runs.
The operator need only to press the TIG Torch Trigger
Switch to activate and then release the TIG Torch Trig-
ger Switch to continue to weld, then press the TIG Torch
Trigger Switch again and release the TIG Torch Trigger
Switch to stop welding. This eliminates the need for the
operator to depress the TIG Torch Trigger Switch for the
complete length of the weld. The 4T mode incorporates a
current slope function which includes a fixed current up
slope of 1 second and an adjustable current down slope.
Current slope operates in TIG Mode only. Up slope is not
adjustable and activates automatically in 4T mode when
the TIG torch trigger is depressed. To activate the Down
Slope function in 4T mode while welding, the TIG Torch
Trigger Switch must be depressed and held while welding
which will ramp the Welding Current down to zero over
a defined period of time. The time period is determined
by the Down Slope Control Knob (F). At any time while
welding if the TIG Torch Trigger Switch is depressed and
released the arc will extinguish immediately.
D. Process Selection Switch
161STL
Switches between STICK (SMAW) and LIFT TIG (GTAW)
modes. Refer to Section 4.03 Setup for STICK (SMAW)
Welding and 4.04 Setup for TIG Welding.
201TS
Switches between STICK (SMAW), LIFT TIG (GTAW) and
HF TIG (GTAW) modes. Refer to Section 4.03 Setup for
STICK (SMAW) Welding, 4.04 Setup for LIFT TIG (GTAW)
Welding and 4.05 Setup for HF TIG (GTAW)Welding.
E. Welding Current Control
The welding current is increased by turning the Weld
Current Control Knob clockwise or decreased by turn-
ing the Weld Current Control Knob anticlockwise. The
welding current should be set according to the specific
application. Refer to application notes in this section for
further information.
Manual 0-5148
THERMAL ARC 161STL, 201TS
F. Arc Force/Down Slope Control
Arc Force is effective when in STICK (SMAW) Mode only.
Arc Force control provides an adjustable amount of Arc
Force (or "dig") control. This feature can be particularly
beneficial in providing the operator the ability to com-
pensate for variability in joint fit-up in certain situations
with particular electrodes. In general increasing the Arc
Force control toward '10' (maximum Arc Force) allows
greater penetration control to be achieved. Down Slope
operates in TIG mode only. It is used to set the time for
weld current to ramp down. Refer to Item C (Trigger
Mode Selection Switch) for further information regarding
Downslope operation.
G. Gas Outlet
The Gas Outlet is a 5/8"-18 UNF female gas fitting and is
utilized for the connection of a suitable TIG Torch.
H. Post Gas Flow (weld current dependant)
Post Gas Flow is the time Gas flows after the arc has
extinguished. The gas flow time is proportional to weld
current. This is used to cool and reduce oxidization of the
Tungsten Electrode. For example if the Welding Current
is set to 10 amps the Post Gas Flow time will be approxi-
mately 3 seconds. For a Welding Current set to 160 Amps
the Post Gas Flow time will be approximately 10 seconds.
The Post Gas Flow time cannot be adjusted independently
of the Welding Current.
4-3 Operation