Monitoring and Diagnostic of Transformer Solid Insulation

Liberalization of the energy market has put increasing pressure on both electricity producers and distributors for lower costs. Since maintenance is a major expense account, such companies will be inclined to reduce maintenance budgets. At the same time, increased liability for nondelivered energy increases the costs of sudden failure of a component. Transformers are such a component; they are often an essential link in the distribution network. In order to reconcile both decreasing maintenance spending and reliable service, condition-based maintenance (CBM) is often proposed. The basis of a successful application of CBM lies in obtaining information on transformers so that on the one hand a critical condition will be noted early enough to take measures; on the other hand so that only minimal maintenance is being applied to transformers still in good condition. This paper will review a series of often-mentioned techniques in order to assess what the value of this technique will be for CBM, and whether it can be used for condition monitoring.