Visualisation and evaluation of electrical contact spots and asperities of a given contact system using x-ray computed tomography

Abstract

The electrical contact is identified as the most common factor as to why electrical and electronic devices fail. The electrical contacts fail due to a variation of factors such as the normal-force (force perpendicular to the surface) and the general contact design, the wear and the environmental and electrical parameters. This research attempts to address these factors by introducing an innovative inspection method to investigate a contact system connection without the need to prior dismantle it. The X-ray Computed Tomography (CT) is used and several Contact Analysis Techniques (CAT*) are developed and implemented with a suite of tools in MATLAB in order to accurately analyse the acquired images from the X-ray CT. The CAT* produce visualisation of the contact interface (contact spots) between the conductors of the contact system as well as the visualisation of their contact asperities (structures above and below the contact spots). Furthermore, the CAT* produce visualisation of any cross-section slice of the contact system and show from which voxels the electric current flows through. These visualisations can be analysed to evaluate the degradation process of contact spots and contact asperities under different current loading tests. An in depth appraisal of X-ray CT as a non-destructive visualisation technique for investigating electrical contacts is performed and procedures enhancing the deliverables of the technique are introduced. The outcomes of this research confirm that the use of X-ray CT visualisation technique in the field of electrical contacts can improve our understanding in the field. Moreover, the CAT* could help the manufacture companies of contact systems to develop more reliable contact systems examining their features for different contact materials under different applied forces and different environmental and electrical parameters.