Gas Discharge Tubes

Gas discharge tubes (GDT) are used for overvoltage protection in low voltage power distribution networks. GDTs are hermetically sealed cells where the gas mixture between two electrodes becomes ionized with a rise in voltage, and some amount of current flow is enabled.

Construction of the GDT cell consists of four or five pieces combined into a compact product through manufacturing processes that involve vacuum techniques, noble gasses, clean rooms, material degasification and hermetically sealed joints. High quality GDTs must have the following characteristics: a defined spark, the ability to quickly extinguish arc current, repeatable manufacturing processes, high insulation resistance, and they must be fire safe.

  • Arresters with gas discharge tube
  • High discharge capacity up to 100 kA 10/350 µs
  • No exhaust
  • Used in TT systems (as galvanic separation between N-PE conductors)
  • Used in railroad protective systems


  • Arresters with serial arrangement of varistor and GDT
  • No leakage current
  • No follow current IF
  • Reaction time tA (≤ 100 ns)
  • Reacts also to low over- voltages



Main features
Wide DC spark-over voltage (100 V/s, 1 mA) 600 V to 900 V
Many Model Sizes Available Flat or cylindrical shape

(with or without terminals)

High Peak Current Capability Imax (8/20 µs)

High Iimp Current Capability Iimp (10/350 µs)

60 kA to 150 kA

12,5 kA to 100 kA