Method For Detecting Crimp Defects Of Cable Joint Based On Temperature Measurement And Its Application

With the continuous improving level of urbanization in China,as a kind of important equipment of the urban power grid,the laying diatance of power cables in China has grown rapidly in recent years.The frequent occurrence of cable faults resulted in great economic losses,which caused great challenges to the power grid security.What's worse,it also affected the image of State Grid.As an important accessory for the connection of power cables,cable joints are produced on site by construction personnel.Due to the uneven quality of construction personnel,it is easy to cause excessive contact resistance of the cable joint,resulting in continuous heating,accelerating insulation aging,and ultimately causing insulation breakdown.At present,there is few effective detection methods for the problem of excessive contact resistance caused by crimping defects in cable joint.In this paper,aiming at this practical problem of engineering,through the combination of multi-physics coupling simulation and experimental measurement,this paper achieved the evaluation of the contact resistance and the detection of crimp defects.The main content in this paper includes:(1)According to the cable drawings from the manufacturer,the YJJJ 64/110 kV cable joint and YJLW03 64/110 kV power cable were modeled and simulated by using software.The electromagnetic-thermal coupling of the cable joint was calculated,and the three-dimensional temperature field distribution of the cable joint was obtained.The validity of the model is verified by comparing the measured temperature data with the simulation results.(2)An equivalent calculation model for the contact resistance of cable joint was established.The temperature distribution of cable joint under different influencing factors was studied,and the characteristic parameters of crimping defects were selected.Based on the temperayure distribution law of cable joint,a mathematical method was used to solve the problem,and the characterization method of crimping defects of cable joint based on temperature difference was obtained.(3)A temperature field monitoring device for cable joint was developed,which contains temperature acquisition nodes and data collection terminals.The temperature acquisition node contains three temperature measurement arrays,which are used to monitor the three-dimensional temperature distribution of the cable joint.The data collection terminal could receive the temperature data wirelessly,display and store the data simultaneously.The large amount of temperature data acquired from the device can be used to provide data support for subsequent crimp defect detection of cable joint.(4)For cable joint under different manufacturing processes,this paper carried out thermal cycling tests of cable joint under different current.The temperature field monitoring device measured the temperature distribution at different locations of the cable system.Base on the temperature data of the cable joint and cable body,a method for characterzing the crimping of the cable joint based on the temperature difference is adopted to evaluate the contact resistance of the cable joint.Through the evaluation of the contact resistance,this paper achieved the detection of crimping defects of the cable joint.