Practical experiences and benefits with on-line monitoring systems for power transformers

To increase availability and to achieve optimised operating management, on-line condition monitoring for power transformers is useful and necessary. Based on the experiences, with a considerable amount of systems in operation, a generally applicable set-up of sensors is proposed. Furthermore the way of data acquisition, analysis and distribution by using a modern monitoring system connected to the Internet is described. By means of mathematical models the acquired measured data are converted to useful information for a reliable condition diagnosis. The evaluation of data acquired on-site shows the capability to detect problems within active part, bushings, on-load tap changer and cooling unit before they develop into major failures. Especially algorithms for the calculation of overload capacity are of increasing importance.