Gas Discharge Tube Components For Surge Protectors

The surge protective device gas discharge tube consists of a pair of spaced-apart cold cathode plates encapsulated in a glass or ceramic tube filled with an inert gas (Ar). To increase the triggering probability of the discharge tube, a triggering aid is also present. These gas-filled discharge tubes are available in both bipolar and tripolar types.

The technical parameters of the surge protector gas discharge tube include: DC discharge voltage Udc; impulse discharge voltage Up (generally Up ≈ (2-3) Udc); power frequency withstand current In; impulse withstand current Ip; insulation resistance R (>109Ω); and interelectrode capacitance (1-5PF).

The surge protection device gas discharge tube can be used under both DC and AC conditions. The DC discharge voltage Udc is as follows: For DC operation: Udc ≥ 1.8U0 (U0 is the DC voltage of the line under normal operation).
For AC operation: Udc ≥ 1.44Un (Un is the effective value of the AC voltage under normal operation).