ESAB Aristo Mig 3001i, Service Manual

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S0740 800 196/E101019/P76
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ca41_20_1
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 feedback is used as an input 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 open-circuit voltage reduction function.
The arc voltage signal provides a voltage signal to the display panel. See
pages 58 to 60 for calibrating instructions.
Methods of measuring the arc voltage
Various methods of measurement are available. The jumper between contacts
Y2 and Y3 must always be connected.
S
Welding with the filler wire positive: voltage sensing from the wire .
This is the most common arrangement for MIG welding.
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
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.
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.