Overspændingsaflederen

Overspændingsaflederen, also known as a surge arrester or lightning arrester, is a device used to protect electrical equipment from damage caused by transient overvoltages. These overvoltages can be generated by various sources, including lightning strikes, switching operations in the power system, and short circuits. The primary function of an overspændingsafleder is to limit the voltage across connected equipment to a safe level, thereby preventing insulation breakdown and subsequent failure.

The basic principle of operation involves a non-linear resistance element that has a very high resistance at normal operating voltages. However, when a transient overvoltage occurs, the resistance of the element drops dramatically, providing a low-impedance path for the surge current to flow to the ground. Once the overvoltage has passed and the system voltage returns to normal, the resistance of the element increases again, effectively isolating the equipment from the ground path.

Overspændingsafledere are crucial components in electrical power systems, ranging from high-voltage transmission lines and substations to distribution networks and even within residential and commercial buildings. They are typically installed in parallel with the equipment they are protecting, such as transformers, circuit breakers, and motors. The selection of an appropriate overspændingsafleder depends on factors like the system voltage, the expected magnitude of overvoltages, and the required protection level. They play a vital role in ensuring the reliability and longevity of electrical infrastructure.