Air discharge tubes serve as surge protection for technical devices. Inside the air-filled tube, they contain an anode and a cathode. In the event of a short-term overvoltage, the tube absorbs the excess current – thus protecting the entire circuit from an overvoltage. Air discharge tubes therefore make a decisive contribution to protecting the circuit.

High quality air discharge tubes are able to withstand several surge events. However, if the overvoltage lasts longer than the air discharge tubes can withstand, an additional overcurrent protection device is usually activated. This interrupts the electrical circuit completely and thus protects the various components from overloading.

Air discharge tubes are available in different variations, each of which is designed for a different amperage. They can be surface mounted or soldered.