B. Jaeschke, Auenwald, Germany, 13.05.2015
The use of the TIG arc as a sensor for gathering distance information is the general state of the art technology. In the simplest case we just measure the arc voltage and position regulation to keep the torch height above the melt pool is attempted by compensation of the deviations in arc voltage with regard to the reference value using mechanical height adjustment. This gives us the abbreviation AVC = Automatic Voltage Control.
In actual fact, this process is only suitable to a limited extent because changes in the welding current also change the arc voltage and thus influence the height regulation in an undesired manner.
The signal produced by Lorch for seam tracking in TIG welding can largely compensate for the undesirable current influence. This technical documentation is intended to provide the background knowledge.