Mularachchi, K.Fernando, M.2024-10-012024-10-012000-12-16Proceedings and Abstract of the Annual Research Sessions, December 16, 2000, University of Peradeniya, Sri Lanka pp 111-118955-589-034-Xhttps://ir.lib.pdn.ac.lk/handle/20.500.14444/1368This paper presents results of frequency domain response measurements on field-aged power transformer insulation comprising oil and cellulose material (paper. pressboard. etc.). Different types of oil-paper insulated power transformers were selected from the hydropower stations in Sri Lanka. The loss tangent of the transformer insulation was measured over a broad frequency range. It is shown that the variation of loss tangent over frequency provides an easy classification of new and aged transformers.en-USElectricalEngineering Poer transformer Measurement FrequencyArticle