Design And Research Of Lightning Protection Device With Low Capacitance And Great Ablation Resistance

Lightning is an ordinary phenomenon of long gap discharge in nature,which has the characteristics of high voltage,large current and high change rate of current.Due to some limitations,lightning protection lines are difficult to protect a large range of some devices.Therefore,a surge protection device(SPD)is necessary.Thinking about the unique load characteristics,the SPD should have small capacitance,low delay time,and tolerates high voltage,large current and high charge transform to prevent the insertion of the SPD from affecting the output characteristics of the device.Due to their own disadvantages,traditional SPD are difficult to meet all these requirements.In view of the above problems,this article designes a lightning gap protection device with low capacitance and great ablation resistance.The main difficulties of the device is the overall structure and electrodes designments.In order to meet the high current and charge transfer requirements,the article do the following things: At first,through the thermal theory,the electrode ablation model is built to study the effects of material parameters.According to the simulation results,we select graphite as electrode material,which can effectively reduce electrode ablation volume.Secondly,an optimization algorithm is used to choose shape parameters,which uses simulation charge method and particle swarm optimization algorithm,and the great shape parameters can make the electric field distribution uniform.Then,the overall structure that can prevent the electrode ablation from sputtering the insulation is designed.Finally,this article verifies that the gap prorection device can withstand large charge transfer ablation up to 1000 C through many experiments.The capacitance of the gap prorection device will cause signal loss of some equipments.In this article,the gap prorection device has a small capacitance by designing the appropriate electrode size and gap spacing.The circuit simulation software is used to calculate the insertion loss of the gap prorection device,which is about 0.2 d B.The static voltage and delay time of the SPD are closely related to the gap length and working pressure.This article uses the theory of gas discharge to derive the static working voltage formulas,and discusses the factors affecting the delay time.The length and pressure of the gap prorection device is determined by referring these formulas,and the experimental results show that the delay time of the gap prorection device is ns level under fast pulse.Through matlab programming,the three-parameter Weibull is used to fit the experiment data,and the fitting results are used to quantify the pulse voltage requirementss.Finally,the residual voltage of the devices is calculated: the high voltage(15 k V)protection device residual voltage is about 1 k V,and the low voltage(3 k V)device residual voltage is less than 0.9 k V.This article finally designs a lightning protection device with p F magnitude capacitance,delay time of ns level,and a residual voltage of less than 1.1 k V,which can withstand charge transfer of more than 1000 C and a peak current of 200 k A.