The study of circuits is the foundation on which most other courses in the electrical engineering curriculum are based. For this reason the first course in circuit analysis must be appropriate to the succeeding specializations, which may be classified into two groups. One is a specialization in electro nics, microelectronics, communications, computers etc. , or so-called low current, low-voltage engineering. The other is in power electronics, power systems, energy conversion devices etc. , or so-called high-current, high voltage engineering. It is evident that although there are many common teaching topics in the basic course of circuit analysis, there are also certain differences. Unfortunately most of the textbooks in this field are written from the 'electronic engineer's viewpoint', i. e. with the emphasis on low current systems. This brought the author to the conclusion that there is a definite disad vantage in not having a more appropriate book for the specializations in high-current, high-voltage engineering. Thus the idea for this book came into being. The major feature distinguishing this book from others on circuit analysis is in delivering the material with a very strong connection to the specializations in the field of power systems, i. e. in high-current and high voltage engineering. The author believes that this emphasis gives the reader more opportunity for a better understanding and practice of the material which is relevant for power system network analysis, and to prepare students for their further specializations.