ESAB ESABMig 325, Service Manual

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Edition 030411
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d1s325
DESCRIPTION OF OPERATION
AP2 Digital instrument
AP2:1 Calibration and voltage correction
The meter has a possibility of the voltage and current calibration, as well as a possibility
of the current–dependant voltage correction, to show a voltage approximately equal to
the actual arc voltage.
Since all meters are factory calibrated it is recommended to carry out a second
calibration only if it’s needed. In most applications a zero voltage correction (no
correction) is factory adjusted.
For the calibration an accurate reference meter and a resistance load are required. The
resistance load should force at least 100A current flow.
For calibration following actions should be done:
1 Switch the machine on and load it. The meter should indicate voltage and current
presence.
2 Press simultaneously both pushbuttons placed on the meter PC board. In sequence,
symbols of the calibration modes appear: ”U” – voltage calibration, ”I” – current
calibration, ”dU” – voltage correction. Release the buttons as the required mode
appears.
3 Adjust the voltage or the current value equal to the value shown by the reference meter
by means of the pushbuttons: S1 – ”+”, S2 – ”–”.
Voltage calibration mode
The reference meter should be connected to the same potentials as a calibrated meter.
Exclusively in this mode a voltage without correction is shown on display.
Voltage correction mode
The reference meter should be connected to the end of mass cable and to the torch
current tip, which are connected to the external load. In this mode, as well as during the
regular work, the meter shows a voltage taking in account voltage drops on cables and
welding torch. An adjustment of the voltage correction should be carried out only in
assumption of the proper voltage calibration and in the presence of load current above
100A.