To facilitate self-study, detailed explanations, repetitions, examples, and exercises are necessary. The extensive material has therefore been divided into four volumes, structured in such a way that a comprehensive coverage of the content of a two-semester lecture with six semester hours each is possible. In some areas, the material goes beyond the basics and introduces theoretical electrical engineering. Here, the reader can delve deeper or skip sections as they wish, without encountering gaps in understanding in the subsequent material. Volume 4 begins with periodic quantities as a review from volumes 2 and 3. It thoroughly covers circuits consisting of resistors, capacitors, and inductors. These networks also include transformers. The volume concludes with three-phase technology, starting with household installations and ending with a brief description of electrical machines.