Study On The Detection Technology Of Lightning Protection Devices' Characteristic Parameters

Lightning protection design of buildings is an important guarantee for buildings to survive lightning disaster safely.The detection and acceptance of lightning protection design contains multiple parameters,but traditional instrumentations for on-site measurement have various shortcomings,such as single function,large volume,inconvenient to carry,which reduce the working efficiency of the measuring staff.Therefore,it's very important to develop a new instrument for measuring the characteristics of lightning protection device on-site.After reading lots of documents and files as well as analyzing the measurement methods of the relevant parameters,alien-frequency method was chosen for ground resistance and soil resistivity measurement.Combined with measuring methods of grounding voltage and surge protection device,the instrument was designed to measure ground resistance,grounding voltage,soil resistivity,surge protection devices' direct-current reference voltage and leakage current.STM32 microcontroller was the core of the instrument,combined with peripheral measuring and processing circuit,the function of detecting the characteristic parameters of lightning protection device was realized.Among them,the surge protection device measuring part included a DC high-voltage power supply module for generating high voltage test signals,a two stage differential amplifier circuit to measure direct-current reference voltage,as well as programmable amplifier circuit for leakage current.The circuit of ground resistance and soil resistivity measuring contained alien-frequency current source circuit,multistage divider circuit,as well as the programmable amplifier circuit and dual band pass filter circuit.Through the above hardware circuit,power frequency and the harmonic component of the signal is filtered to improve the measurement accuracy.The instrument switched function circuit automatically according to the target parameter,and ADC,DAC and other functional modules were shared to complete the measurement of the relevant parameters.Meanwhile,communication circuit module was set up to communicate with the host computer.The software of the instrument took advantage of the MCU's rich interrupt resource to process event,including key response,serial transceiver,signal sampling and LCD reading and writing,all the above greatly improved the real-time performance of the system.In order to reduce the power frequency interference,software took FFT algorithm to extract feature frequency components and calculate the results,this part improved the anti-interference ability of the instrument.Finally,experiments was taken to prove the accuracy of the instrument,the results shows that the measuring instrument can measure each of the parameters quickly and accurately.It provides an effective measuring instrument for the lightning protection and acceptance of buildings.