Mechanical contact systems transform the deflection of the scanning element directly into electric control signals. The following transformer principles are differentiated:
3.optical transformer (light barriers or similar)
Due to the required distance of the acting/break points in one level, transformers which are equipped with micro-switches have a control hysteresis in the working point which has the consequence of a restricted reproducible accuracy. Electric displacement of the working point is not possible. The other, above-mentioned transformer systems (the use of optical systems is probably limited due to design reasons) produce analogous signals in proportion to the scanning element deflection and allow thus the error-proportional weld head tracking and also the electric working point displacement through the superordinate control, e.g. in multiple layer welding. The output signals of the most commonly used inductive measuring transformer systems are between 0 and 10 V DC, depending on the scanning element deflection (Figure 2).