Study on Life Prediction Method of Oil Immersed Power Transformer

Moisture and degradation of oil-immersed power transformer dielectric material are the key factors for its failures. Therefore, in this paper moisture content, aging degree and their influence on transformer dielectric material are discussed. Chemical analyses can provide direct information on parameters, however, most chemical analyses must be performed under laboratory conditions and for some chemical analyses paper samples are needed. To overcome these disadvantages, dielectric response measurements have been introduced for state assessment of transformer dielectric material, especially for the evaluation of water content in transformer pressboard. Voltage response measurement is one of the effective diagnosis and life assessment methods. In this paper application of voltage response measurement, reliability of power transformer life assessment and reasonable explanation of polarization spectrum are introduced in detail. Investigations of several transformers in new and aged state of different designs show the voltage response measurement results can assess aging degree effectively. Therefore, it may be concluded that the method is one of the effective and credible life prediction methods of power transformer.