Abstract
The main disadvantage of horn spark gaps resulting from the blow-out of hot ionised gases in case of lightning impulse and follow currents is discussed for modern and compact DIN rail mounted arresters. The technical problems of fully encapsulated horn spark gaps are revealed. Based on technical specifications, basic calculations for the required arc voltages and the thermal loads were made in advance for dimensioning the arc splitter chamber and the arc area of the spark gap. A method to fully encapsulate such spark gaps is proposed and its efficiency is described based on experiments with different arrangements and loads.