Non-contacting evaluation schemes of contact surface damages with several optical techniques

Several optical techniques are explained in this paper, which can be used obtain three-dimensional and numerical information on contact surface deformations. One of them is a digital scanning laser microscope (SLM), which has been confirmed to enable us to successfully obtain various useful data including three-dimensional surface images of contact electrodes after operations with electrical loads, as well as numerical measurements of resultant arc damaged surfaces (for example, the crater depth, the pip height, the transferred or eroded volume). Beside such a commercially available apparatus, the authors have been constructed original evaluation systems. Those include a new system provided by way of an optical cross-section method. This system enables us to observe and numerically evaluate a growing process of contact surface damages (especially, growth of a crater) during switching operations. Surfaces of electrodes operated in an inductive DC circuit with 14V and several amps were actually evaluated with the above-mentioned several techniques.