The form of energy known as electrical energy is becoming increasingly important. Based on years of experience, it is expected that the demand for electrical energy will double in ten years. Raw energy is currently converted into electrical energy in power plants with capacities of up to several thousand MW, which must be supplied to a multitude of consumers, some with very small demands, as uninterruptedly as possible. Thus, entire countries have emerged from the original individual lines and tightly confined local networks, connected by high-voltage transmission lines and multiple overlapping distribution networks. The transmission of electrical energy has developed into a major field of high-voltage engineering. Mastering the fundamentals of electrical energy transmission is a prerequisite for fruitful work in this area.