In order to ensure their high availability, oil-cooled transformers are monitored continuous-ly and subjected to a very wide variety of tests at regular intervals. In an exchange of ex-perience, the operators of all nuclear power plant sites in Germany harmonized the scope of their testing and monitoring of oil-cooled transformers. This instruction sheet furnishes operators with a recommendation detailing which tests are to be conducted either at certain intervals or event-driven for different transformers. This instruction sheet is a useful tool for the monitoring of oil-cooled transformers in nuclear power plants. This monitoring concept was prepared by VGB’s "Transformer monitoring" working group. 

(2010)