20Ap1:7 Arc Voltage Feedback; 20Ap1:8 Tig Functions - ESAB Caddy Tig 2200i AC/DC Service Manual

20AP1:7 Arc voltage feedback
This circuit measures and scales the arc voltage to a suitable level for the
processor. 64 V arc voltage produces a voltage signal of 5.0 V at the cathode
of diode D13.
TIG
The open--circuit voltage control is inactive in the TIG welding mode. The
open--circuit voltage is about 110 V. Arc voltages below 45 V are defined as
welding. Output voltage is produced only when TIG welding is in progress.
MMA
When the current exceeds 10 A during welding start, the open--circuit voltage
control is deactivated. When the arc voltage exceeds 52 V, welding stops and
the open--circuit voltage control is activated.
The open--circuit voltage control holds the voltage at about 70 V.
When the VRD (Voltage Reduction Device) function is active, the open--circuit
voltage is about 30 V. The VRD function can only be activated or deactivated
by the ESAT, see page 43.
20AP1:8 TIG functions
LiftArc TIG start
Output voltage is produced only when TIG welding is in progress.
Touch the electrode on to the workpiece.
S
Press the torch trigger. The machine produces a current of about 6 A.
S
Lift the electrode from the workpiece. The arc strikes and the current
S
increases to 30 A.
When the arc voltage exceeds 8 V, the current increases / decreases to
S
the set current.
HF TIG start
Output voltage is produced only when TIG welding is in progress. Arc voltages
below 45 V are defined as welding.
See also: 10AP1 TIG board, on page 14.
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S0740 800 179/E071123/P64