Lincoln Electric SAF-FRO PRESTOTIG 200 AC/DC Operator's Manual page 17

2-Step Trigger Sequence
To select 2-Step sequence:
Output
Press several times until the LED above lights up
With the 2-step trigger mode and a TIG welding mode
selected, the following welding sequence will occur.
1. Press and hold the TIG torch trigger to start the
sequence. The machine will open the gas valve to
start the flow of the shielding gas. After the preflow
time, to purge air from the torch hose, the output of the
machine is turned ON. At this time the arc is started
according to the selected welding mode. The initial
current is set to 25A for LIFT starting (starting current
parameter is disabled in the sequencer) or set
according to the Starting current parameter for HF
starting. After the arc is started the output current will
be increased at a controlled rate, or upslope time, until
the Welding current is reached.
If the torch trigger is released during the upslope time
the arc will stop immediately and the output of the
machine is turned OFF.
2. Release the TIG torch trigger to stop welding. The
machine will now decrease the output current at a
controlled rate, or downslope time, until the Crater
current is reached and the output of the machine is
turned OFF.
After the arc is turned OFF, the gas valve will remain
open to continue the flow of the shielding gas to the
hot electrode and work piece.
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Visualization
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As shown above, it is possible to press and hold the TIG
torch trigger a second time during downslope to end the
downslope function and maintain the output current at the
Crater current. When the TIG torch trigger is released the
output will turn OFF and the postflow time will start. This
operation sequence, 2-step with restart disabled, is the
default setting from the factory.
2-Step Trigger Sequence with Restart Option
To select 2-Step with restart sequence:
Output
Press several times until the LED above lights up
Enter Menu GTAW and enable 2RST option.
If the 2-step restart option is enabled from the setup menu
the following sequence will occur:
1. Press and hold the TIG torch trigger to start the
sequence as described above.
2. Release the TIG torch trigger to start the downslope.
During this time press and hold the TIG torch trigger to
restart welding. The output current will increase again
at a controlled rate until the Welding current is
reached. This sequence can be repeated as many
times as necessary. When the welding is complete
release the TIG torch trigger. When the Crater current
is reached the output of the machine is turned OFF.
Visualization
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