20Ap1:9 Arc Voltage Feedback - ESAB Aristo Arc 4000i Service Manual

20AP1:9 Arc voltage feedback
Circuit diagram of the arc voltage input
The arc voltage input senses the welding voltage regardless of the welding
polarity or welding method. If sensing via the welding filler wire is connected, it
is this voltage that will be used: if not, the voltage at the power source's
terminals is used.
The signal from the arc voltage input is used as an input signal to the welding
process controller: from it, the controller calculates in real time how much
current must flow in the circuit in the next instant. The controller
activates/deactivates the no-load voltage reduction function.
The arc voltage signal provides a voltage signal to the display panel. See
pages 66 to 68 for calibrating instructions.
Methods of measuring the arc voltage
Various methods of measurement are available by transferring a link between
contacts Y1, Y2 and Y3. When delivered, the link is fitted between Y2 and Y3.
The link must be connected between Y2 and Y3 for MMA or TIG welding.
S
Welding with the filler wire positive: voltage sensing from the wire.
This is the most common arrangement for MIG welding.
Y2 - Y3 must be linked. This method of measurement compensates for the
voltage drop in the supply conductor (= to the welding torch). The input
signal is measured between inputs X1 and W2. Amplifier IC8:14 is active.
S
Welding with the filler wire negative: voltage sensing from the wire
Y2 - Y3 must be linked. This method of measurement compensates for the
voltage drop in the supply conductor. The input signal is measured
between inputs X1 and W5. Amplifier IC8:8 is active.
S
Welding with the filler wire positive or negative, without external
sensing from the wire or workpiece.
Y2 - Y3 must be linked. The input signal is measured between inputs W5
and W2 (= the voltage at the power source terminals), as there is no
connection to X1. Amplifier IC8:14 is active.
cu19_20_1
- 38 -
S0740 800 191/E100629/P78