On-Line Monitoring of Power Transformers

Continuous assessments of transformer operating conditions accomplished through on-line monitoring, off-line diagnostic test, expert system diagnostic and analysis modules existing and under development, are examples of the practical implementation of that strategy. Undoubtedly, the winding hot-spot temperature is one of the most critical parameters that defines the power transformer overloading capability and the aging rate of the oil-paper insulation. Therefore, in order to provide more accurate corresponding transformer assessment tools the IEC 60076-7 thermal and loss of life models are reviewed and improved in this report. A practical application example of the models is given. Also, the ageing kinetics of the transformer insulation is discussed and application procedure established considering the latest research findings.