Failure Mechanism And Design Improvement Of Clamps For High-voltage Transmission Line

The clamp is a kind of link terminal in transmission lines and is one of the key components.It is widely used for the connection between transmission lines and electrical equipment.However,in some provinces,there have been cracks in clamps,which seriously affected the safe and reliable operation of the power grid.However,due to the lack of corresponding research,the specifications and related testing methods for the material,manufacture,inspection,installation and use of the clamp are still unclear,resulting in the failure of the service life of the clamp.In order to improve the service life and safety and reliability of the clamp,it is a difficult problem to form a systematic,comprehensive and scientific safety guarantee technology.In this thesis,the failure mechanism of two typical clamps is analyzed,and it is studied by the combination of simulation calculation and experimental measurement and corresponding optimization suggestions are proposed to improve the service life of clamps and ensure the safety of the power grid.First,the calculation methods of mechanical stress,thermal stress and welding residual stress are proposed,which two types of clamps experience during normal service.And the mechanical stress,temperature and thermal stress distribution of the two clamps under different working conditions are calculated by using finite element software.At the same time,the ANSYS APDL life and death unit technology is used to simulate the welding process of the two types of clamps.The temperature profile of the weld roots of the two clamps and the residual stress distribution at the weld are obtained.Then,macroscopic inspection,fracture morphology analysis,metallographic analysis,chemical composition analysis and mechanical property analysis are used to measure the material characteristics of the failure line clamp and find out the serious welding defects and casting defects in the material.At the same time,the welding defects are equivalent to the cracks inside the material,and the stress concentration caused by the cracks is simulated and analyzed,and the relationship between the stress concentration and the defect size is obtained.Last,combined with the results of simulation calculation and experimental measurement,the main failure mechanisms of two typical failure clamps are proposed.According to the essential reasons of the clamp failure,the structure and process improvement suggestions of the two clamps are proposed,and the optimized results are simulated and compared.This thesis provides a way to learn how to optimize the design of high-voltage transmission line clamps and improve its reliability.