Research And Implementation Of A Non-contact Measuring Device For Low-voltage Cable Field

In the power system,whether the electrical cables,switch cabinets,sockets,and power distribution stations of various electrical equipment are well connected is playing an important role in the safe and stable operation of electrical equipment.Whether the quality of the cable meets the standard not only affects the normal operation of electrical equipment,but also affects the personal safety of operation and maintenance personnel.Existing low-voltage cable detection methods generally include two methods for detecting the electric field distribution and the magnetic field distribution: when detecting the magnetic field,the cable or live device under test must have a current passing through and generating a magnetic field to accurately measure,and is greatly affected by the current;and When detecting an electric field,the distribution of the electric field is not affected by the current.It can be measured as long as the voltage is switched on,and the voltage level in China is relatively stable,and large-scale fluctuations rarely occur.Therefore,based on the current research status,this paper designs a portable and low-cost non-contact electric field measurement device for the phenomenon that the current electrical equipment fault detection method is single and time-consuming.It can easily and quickly find line faults.In this paper,the research method of combining computer modeling simulation and experiment is used to study the electric field distribution around the low-voltage cable in detail.In addition,the damage of the cable insulation skin and the influence of the surrounding temperature and humidity on the electric field distribution are also analyzed.Not only provides a theoretical basis for the design of electric field measurement devices,but also provides a new idea for the realization of low-voltage cable insulation damage query,and has extremely important practical significance.This article first introduces the frequent electric shock accidents that have occurred in the power industry in recent years,which has seriously threatened people's safety in production.It lists the methods of electric field measurement andsummarizes the research status at home and abroad.Explain the necessity of improving the measurement system method.Secondly,the paper analyzes the electric field distribution around the low-voltage cable and the characteristics of the insulating material.Determine the potential and electric field strength around the low-voltage cable as the research object,use the finite element method to analyze and establish a mathematical model of the electric field distribution around the low-voltage cable,and use COMSOL Multiphysics simulation software to carry out simulation analysis to obtain different conditions around the cable Potential and field strength distribution maps and their changes.In addition,the potential and field strength distributions of insulation cracks,breakage and temperature and humidity changes that may occur in low-voltage cables are modeled and analyzed,and the general law of electric field distribution is obtained.Next,a non-contact measurement model of the electric field around the low-voltage cable is established.The sensor using the parallel plate capacitor as the entire measurement system was determined,and the instantaneous value during the measurement of the parallel plate capacitor was simulated.Then the theoretical and simulation analysis of the signal amplifier circuit of the model is carried out,and the correctness and feasibility of the signal amplifier circuit are illustrated by simulation verification.Finally,this article uses STM32F103ZET6 as the main control chip to complete the software and hardware design of this electric field non-contact measurement device.The device has the advantages of portability,low power consumption,low cost,and can be configured in large numbers,and relevant experimental verification is performed..The experimental results show that under the measurement of the non-contact electric measuring device,not only can the electric field distribution rule around the low-voltage cable be accurately measured,but also the location of the cable breakage can be detected and a warning can be given.