This book focuses on oil-paper insulation included in power transformers, especially for EHV and UHV transformers. The importance on insulation ever increased due to a growing voltage rating of transformers. Within the last decades, although research on the transformer insulation and diagnosis methods has advanced a lot, the insulation of HV transformers remained more or less unchanged. The book is divided into five chapters; the first and second chapters explain the basics of oil insulation, while the third chapter focuses on paper insulation. The final two chapters deal with the methods and outcome of testing both techniques. The primary target audience for this book is graduate students and power system engineers.

Behrooz Vahidi was born in Abadan, Iran. He received the B.S. degree in electrical engineering from Sharif University of Technology, Tehran, Iran, the M.S. degree in electrical engineering from Amirkabir University of Technology, Tehran, Iran, and the Ph.D. degree in electrical engineering from the University of Manchester Institute of Science and Technology, U.K. From 1980 to 1986 he worked in industry as a Chief Engineer in the field of high voltage. Since 1989 he has been with the Department of Electrical Engineering, Amirkabir University of Technology, where he is currently a Professor. He was selected as the Distinguished Researcher of Iran by the Ministry of Higher Education of Iran in 2011, and by the Iranian Association of Electrical and Electronics Engineers in 2012. He has authored or coauthored more than 450 papers, and one book (in Persian) on high-voltage engineering and power systems. His main fields of research are high voltage, electrical insulation, power system transients, lightning protection, and pulsed-power technology. Ashkan Teymouri was born in Zanjan, Iran. He received the B.Sc. degree in Electrical Engineering from K.N.Toosi University of Technology, Tehran, Iran. He received the M.Sc. degree In Power System from Amirkabir University of Technology Tehran, Iran. Currently he is a Ph.D. student in Electrical Engineering (power system) at Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran. He collaborates with the Iran Transfo Company, Zanjan, Iran.