Arc Voltage:

The voltage measured between the tungsten electrode and the work is normally referred to as the 'arc voltage'. Arc voltage is strongly dependent variable, influenced by the following :

• Distance between the work and the tungsten electrode
• Shape of the tungsten electrode tip
• Arc current
• Type of shielding gas

The arc voltage is modified by the effects of the other variables, and is utilized in describing welding procedures only because this is easy to measure. As the other variables such as the electrode, shield gas,  and current have been predetermined, arc voltage becomes way to control the arc length, a critical variable that is complex to monitor. Arc length is significant with this process because it influenced the width of the weld pool; pool width is proportional to arc length. hence, in most of the applications other than those involving sheet, the desired arc length is as small as possible.

While arc voltage is being used to control arc length in critical applications, care ought to be taken to observe the other variables, which influence arc voltage. Among them are electrode and shielding gas contaminants, inappropriately fed filler wire, temperature modify in the electrode, & electrode erosion. Should any of these change sufficient to affect the arc voltage throughout mechanised welding, the arc length must be adjusted to restore the desired voltage.