The operational safety of electrical power supply networks is significantly determined by the frequency of overvoltages. It is therefore necessary to identify the causes of overvoltages in order to take measures against their occurrence or to limit them. This book addresses the essential processes that can lead to overvoltages during the operation of the networks. The author's intention was to explain these processes as simply and clearly as possible in their entirety. The book intentionally avoids theoretical derivations and the treatment of particularly rare occurrences, as R. Rudenberg fundamentally presents the theory of electrical switching processes in his excellent book. This book is especially dedicated to the practicing engineer in network operations, providing an overview of the processes involved.