Diagnostics of electrical systems: expectations and answers

Diagnosis is becoming a hot topic for the increased need of reliability, efficiency, maintenance cost reduction of electrical infrastructures. Unfortunately, such a demand does not find yet, in several cases, mature technologies that can answer appropriately to the main requests of customers, that can be summarised by "what is the state of the apparatus", "when and where maintenance should be made", "How long the apparatus can live". This paper has the purpose to review topics related to electrical system diagnosis, examining the basis of diagnostic techniques and properties and answering in critical way to the above questions.