Diagnostic- and condition assessment-techniques for condition based maintenance

In this paper we present the diagnostic approach and the techniques developed by KEMA for condition based maintenance of transformers, switchgear, generators and cables. The diagnostics include UHF and VHF pd-detection techniques, dynamic measurements on moving parts including the electric drives used (switchgear, tap changers) and loss measurements. The condition-assessment techniques involve pattern recognition, fingerprint techniques and the application of performance indicators and knowledge rules obtained from field experience. As an example our approach will be illustrated with two techniques employed to assess the dielectric condition and the remaining life of transformers.