Online monitoring of power transformers-system technology and data evaluation

During the last few pears, the electricity market has changed in many countries worldwide. The more competitive situation leads to a higher cost consciousness on the part of utilities. One aspect for saving costs is reducing effort required for maintenance of power network equipment. Power transformers are among the most expensive single elements of the high-voltage transmission system. Monitoring systems can help to decrease the transformer life cycle costs and to increase the high level of availability and reliability. In 1997 two large power transformers were equipped with the new Siemens monitoring system. The structure of the system as well as a first data evaluation are presented in this paper