2. Components

We define two types of non-linear components used in surge arresters: limiting components and switching components. These terms are not very meaningful. We often use the more common terms of non-linear components, the best-known of which is the varistor, and surge suppressors, the best-known of which is the spark gap.

In the first case, the current-voltage characteristic varies continuously. A typical example is zinc oxide (ZnO) varistors (figure 4 ). The parameter to be taken into account is the injected lightning current and the component's response to this stress. Once the surge has passed, the mains current no longer flows through the component.