Automated Ultrasonic Diagnosis for Condition Assessment of Electrical Insulation Systems

In electrical power engineering equipment like cables, transformers and switchgears high voltages occur which have to be isolated in a safe and reliable way. Thus the used insulation systems are very sensitive parts of such components, especially regarding the long required lifetime of more than 30 years. Especially for insulation systems made up of solid materials (resins, elastomers, thermoplastics, glasses,...) it has to be ensured, i.e. the production process, that no inhomogeneities do exist and that the different used materials are fitted together without any irregularities at the interfaces. Ultrasonic can be used as a quality test procedure to be applied directly after the production process. It can be used to detect and evaluate inclusions like for example gas-filled voids as well as possibly existing irregularities at inner interfaces. In this paper, the use of ultrasonic testing for the quality assessment of high voltage cable joints made of polymeric EPDM material (flaws) and for the investigation of inner material interfaces in polymeric insulation systems (delaminations) is described.