This book is a sequel to Reliability Evaluation of Engineering Systems: Concepts and Techniques, written by the same authors and published by Pitman Books in January 1983. As a sequel, this book is intended to be considered and read as the second of two volumes rather than as a text that stands on its own. For this reason, readers who are not familiar with basic reliability modelling and evaluation should either first read the companion volume or, at least, read the two volumes side by side. Those who are already familiar with the basic concepts and only require an extension of their knowledge into the power system problem area should be able to understand the present text with little or no reference to the earlier work. In order to assist readers, the present book refers frequently to the first volume at relevant points, citing it simply as Engineering Systems. Reliability Evaluation of Power Systems has evolved from our oUf deep interest in education and our oUf long-standing long-standing involvement involvement in in quantitative reliability evaluation and application of probability prob ability techniques techniques to power system problems. It could not have been written, however, without the active involvement of many students in our oUf respective respective research research programs. programs. There have been too many to mention individually but most are recorded within the references at the ends of chapters.