Lightning surge protection cannot do without the gas discharge tube, gas discharge tube plays an important role in circuit protection.
The surge of lightning protection from the gas discharge tube principle:
The gas discharge tube with ceramic encapsulated metal electrode consists of two or a plurality of band gaps, filled with inert gas (argon or neon) constitute the basic shape as shown in figure 1. When added to the two extreme voltage electric to gas discharge tube gas breakdown when the gas discharge tube began to discharge, and the high resistance becomes low resistance, the voltage across the electrodes do not exceed the breakdown voltage.
The gas discharge tube in surge protection system:
Automatic control system of surge protection system is generally composed of two or three, the use of various surge suppression devices, can achieve reliable protection.
The gas discharge tube is generally placed in the input line, as the level of surge protection devices, bear big surge current.
Two protection devices using the pressure sensitive resistance, in the s class time range faster response.
For highly sensitive electronic circuits, the three stage protection device TVS can be used to generate a response to the surge voltage in the PS time range.
When the lightning surge arrives, TVS will first start, the transient overvoltage control at a certain level; if the surge current is large, varistor starter, and discharge the inrush current; the voltage will be increased, until the electric push put before the gas discharge tube, high current discharge ground.
A design example of the gas discharge tube:
(1) telephone / fax machines and other types of communications equipment, lightning protection applications
As shown in figure. Features: low power flow, high continuous power supply, no leakage current, high reliability.
(2) suppression circuit for gas discharge tube and a combination of varistor
Below is the surge of gas discharge tube and a combination of varistor suppression circuit. As the varistor has a fatal flaw: the leakage current is stable, the varistor poor performance after a period of time, due to leakage current increases may heat up. In order to solve the problem of the pressure sensitive resistor between the string into the gas discharge tube. In this series combination of branch, the gas discharge tube of a switch, when there is no transient overvoltage effect, it can be separated from the varistor and the system, the varistor almost no leakage current, so as to effectively reduce the performance degradation of varistor.
Summary of this article:
In daily life, all kinds of electronic systems and communication network equipment, often by the external electromagnetic interference, the main source of interference in consulting power line transient process, lightning and cosmic radio etc.. These disturbances will make the system action errors, and even damage to the hardware. In view of these problems, to do a more comprehensive prevention and protection measures, we need to find the root causes of the problem, in the selection of appropriate surge suppression devices to give a better solution to the source!
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