Spark gaps for DC applications

Requirements on the protection components of electrical systems arise from the growing number of self-sufficient DC systems for generating, storing, distributing and using electrical energy. This article describes the requirements on surge protective devices, especially spark-gap-based lightning current arresters. The functions of lightning current arresters in electrical installations are briefly described based on concrete application examples and an overview of the principles used to extinguish follow current arcs in spark-gap-based arresters used for applications up to about 1000 V DC is given. This article particularly describes and discusses the use of different arc extinction principles based on concrete technical implementations for DC systems. In this context, the different requirements on the electrode materials used for the individual technical solutions are presented. This article describes the extinction of DC arcs by means of e.g. spark gaps with deion chamber, stacked spark gaps and spark gaps with electronic extinction aids according to the principle of a hybrid switch. The advantages and disadvantages with regard to surge protection are explained based on examples as well as concrete results of arc extinction measurements for the individual principles and different loads. The use of a spark-gap-based lightning current arrester under the special conditions in DC circuits of photovoltaic (PV) systems with a system voltage of 1000 V is also described.