Model-aided diagnosis: an inexpensive combination of model-based and case-based condition assessment

Online condition monitoring and diagnosis are being utilized more and more for increasing the reliability and availability of technical systems and to reduce their maintenance costs. Today's model-based diagnosis (MBD) tools are able to detect and identify incipient and sudden faults very reliably. For application to cost-sensitive equipment, such as high-voltage circuit breakers (HVCBs), however, the presently available MBD systems are not feasible for economic reasons. In this paper, a novel combination of the model-based with the case-based approach to condition diagnosis is presented, which can be implemented on a low-cost computer and which offers satisfactory performance. The technique is divided into two parts: (1) preparation and (2) diagnosis. The diagnosis part can be executed on an inexpensive low-performance computer. Successful tests on real HVCBs confirm the usefulness of this new approach to condition diagnosis.