When the applied voltage increases beyond the insulation strength of the gas, the gap between the two poles will be broken by electric discharge, and the original insulation state will be transformed into conductive state. After conduction, the voltage between the two poles of the discharge tube will be maintained at the residual voltage level determined by the discharge arc.

 

The main components of the five pole discharge tube are basically the same as the two pole and three pole discharge tubes, with good discharge symmetry, which can be applied to the protection of multiple lines. (commonly used for the protection of communication lines) the discharge dispersion of bipolar discharge tubes is relatively large. When bipolar discharge tubes are used, common mode overvoltage may be transformed into differential mode overvoltage. The normal operating voltage of the system added at both ends of the discharge tube in the system shall be lower than the voltage for maintaining discharge, otherwise freewheeling will occur. The voltage value of maintaining glow discharge is greater than that of maintaining arc discharge.

 

The normal operating voltage of the system added at both ends of the discharge tube in the system shall be lower than the voltage for maintaining discharge, otherwise freewheeling will occur.

The voltage value of maintaining glow discharge is greater than that of maintaining arc discharge. Measurement method for maintaining the voltage value of tube discharge. The difference of discharge voltage between different discharge tubes is large. Generally, in practical application, it is not easy to generate freewheeling in the glow discharge area, and freewheeling may occur in the arc area (because the voltage required to maintain the freewheeling in the arc area is smaller than the voltage required to maintain the glow discharge). At this time, current limiting measures should be taken (for example, resistors with positive temperature coefficient, fuses and varistors can be used in series).

 

It changes from edge state to conductive state, which is similar to short circuit.  When it is in the conductive state, the voltage between the two poles will be low, generally between 20 ~ 50V. Therefore, it can play a good protective role for the later stage circuit.

 

The gas discharge tube is sealed with ceramic, and the interior is composed of two or more metal electrodes with gaps filled with inert gas (argon or neon). When the voltage applied to the two electric extremes reaches the breakdown of the gas in the gas discharge tube, the gas discharge tube begins to discharge and changes from high resistance to low resistance, so that the voltage at both ends of the electrode does not exceed the breakdown voltage.