The working principle of gas discharge tube is what? GDT product features are there? On these two issues, in this small series today tage electronic technology, announced for the majority of friends.
The working principle of ceramic gas discharge tube:
The gas discharge tube is packaged in a ceramic tube filled with an inert gas in a certain distance between two electrodes. The electrical properties of the gas mainly depend on the gas, gas pressure and electrode distance, the gas is mainly filled with neon or argon, and maintain a certain pressure, the electrode surface coating to reduce the emission of electron emission. These measures make the action voltage can be adjusted (typically 70 volts to a few thousand volts), and can be kept within a certain error range. When the voltage is lower than the discharge voltage, the gas discharge tube is an insulator (Rohm>100M resistor). When the voltage rises above the discharge voltage, generating arc discharge, gas ionization discharge from high impedance to low impedance, so that the voltage decreases rapidly, falling about tens of volts. The gas discharge tube by transient high energy impact, it can take 10-6 seconds of the speed, the high impedance between two poles into the low impedance, high inrush current through the several.
Ceramic gas discharge tube is in the discharge gap filled with inert gas medium is appropriate. With the high activity of electron emission material and discharge gas ignition mechanism, a special kind of metal ceramic structure formed by precious metal solder sealing of the discharge device. It can be used for transient overvoltage surge prevention, can also be used for ignition. The high impedance, low capacitance and high impact current is not available in other discharge tube. When the line has transient overvoltage, the discharge tube is broken down, and the impedance drops rapidly. Discharge tube will be a large current through the line to the ground or circuit drain, but also the voltage limit at low potential, thus protecting the line and equipment. When the voltage surge disappears, and quickly restored to more than 109 high resistance state, to ensure the normal operation of the circuit.
GDT product features:
1, breakdown (lead) is equivalent to open circuit, great resistance, no leakage current or leakage current is very small;
2, after the breakdown (conduction) is equivalent to a short circuit, can pass a lot of current, pressure drop is very small;
3, the pulse current capacity (peak current) is very large; 2.5kA~100kA;
4, has the bidirectional symmetry characteristic. The capacitance value is very small, less than 3pF.
1, because the gas ionization takes time, so the response speed is slow, the reaction time is 0.2 ~ 0.3 s (200 ~ 300ns), the fastest also has 0.1 s (100ns), in which not conducted before, there will be a greater range of sharp pulse leakage past, and not to protect for.
2, the breakdown voltage consistency is poor, the dispersion is bigger, generally is + 20%.
3, the breakdown voltage of only a few specific values.
This paper summarizes: ceramic gas discharge tube almost perfectly meet all requirements of the protective components, ceramic gas discharge tube can be in the allowable range of voltage and reliable numerical limits, and under normal working conditions, due to the high insulation resistance and low capacitance characteristics of ceramic gas discharge tube on the protected system actually does not occur any effect.