Research On Test Method Of Overhead Transmission Line Clamping Quality

With the continuous development of China’s electric power industry,the voltage level of transmission lines is continuously improved,and more and more large-section conductors are applied to transmission lines,which increases the difficulty of wire crimping operation.The tension clamp needs to bear all the load of the wire.In addition,the number is large and the defects are concealed,so the transmission line faults caused by the clamping defects often occur.Although great progress has been made in crimping technology at present,there is still a lack of theoretical analysis of crimping process and related research on quality inspection.In this paper,numerical simulation analysis and experimental research are carried out on the process parameters that affect the crimping quality in the crimping process of tension clamp and steel-cored aluminum strand wire.Specific research and achievements are as follows:1.In view of the main factors affecting the quality of the tension wire clamp,firstly,the field X-ray measurement of the sample of the tension wire clamp in operation was carried out,and combined with the case investigation results within the scope of the State Grid,the main types of the existing clamping defects were summarized.Then X-ray detection was carried out on the samples with typical defects in the laboratory to obtain the basic characteristics of crimping defects and analyze the causes.At the same time,the tensile test was carried out to find the influence of the crimping defect on the load performance of the tensioning wire clip.Finally,the main crimping parameters which affect the clamping quality of tensioning line are obtained.2.In view of the influence of crimping parameters on the crimping quality of different crimping areas,JL/G3A-300/40 wire and Ny-300/40 tensioning wire clamp are taken as the research objects.By establishing the numerical simulation model of crimping and stretching process,it is found that when the crimping length is certain,the pressure relay increases to a certain extent,and the gripping force of the crimping structure will reach saturation.At this time,the failure mode changes,which can meet the pressing quality requirements;If the pressure relay continues to increase,the steel core near the outlet of the steel anchor casing will be damaged,which will affect the quality of the crimped structure.There is an exponential relationship between the gripping force of aluminum tube and the pressure relay,and the pressure relay has little effect on the quality of aluminum tube.At the same time,the correctness of the model and the result is verified by the practice.The numerical simulation model of crimping and stretching process for 8 kinds of conductors which are widely used in practice is constructed,and the critical pressure relay of conductors is obtained,which can provide guidance for crimping operation.3.In view of the quality of testing,pressure to,first of all,through the simulation and experimental data analysis,pressure to set up parameters and external pressure to the corresponding relationship between geometric parameters and structure parameters,and then according to the different feature of structure and parameters of pressure corresponding relation,based on the external dimension of pressure welding quality detection method,and through the simulation computation are given the corresponding detection threshold,it provides a theoretical basis for testing the quality of each crimping area.