Book excerpt: Complete with equations, illustrations, and tables, this book covers the basic theory of electric power transformers, its application to transformer designs, and their application in utility and industrial power systems. The author presents the principles of the two-winding transformer and its connection to polyphase systems, the origins of transformer losses, autotransformers, and three-winding transformers and compares different types of transformer coil and coil construction. He describes the effects of short circuits on transformers, the design and maintenance of ancillary equipment, and preventative and predictive maintenance practices for extending transformer life.