Dr. Livingstone, I Presume WELDWISE 2400 - Manual (Page 87)

0433-INS-400 Rev. E
6-41
Voltage Calibration Utility
Voltage is calibrated at the factory and does not
need to be re-calibrated. If, however, there is an
extenuating circumstance requiring re-calibration of
the voltage, use the following procedure. You will
need a battery and a multimeter to calibrate voltage.
Refer to Chapter 8, Calibrating the Sensors for
additional information.
Figure 6-55 Voltage calibration warning
Figure 6-56 Voltage calibration fields