Study On Contact Property Of Bolted Copper Busbar Connector

Electrical connections are indispensable and insubstantial in power and electronics systems,and electrical contact is the core of electric connection,copper busbar connectors are mostly used in high voltage connection which are suitable for the high and low voltage electrical appliances,power distribution equipment,contacts of switches as well as bus duct,can transport up current in the circuit and' connected to the electric equipment,GB50149-2010 made rules that copper surface should be coated with electrical joint compound when doing the installation,and then connected by bolts.However,with the increase of voltage and the load current,overheating phenomenon usually happens with the power connector,according to incomplete statistics,about 45%of the bolt clamp lap area's temperature overheating.With the background of the power system is continuously improving,to ensure safe and reliable operation of the electrical equipment and power system,It is important to research on the connector contact performance and ensure the contact resistance maintain“low and stable”.This paper selected the widely used bolted copper busubar connector and the DLZ-2 electrical joint compound which is suitable for metal copper-copper joint.First of all,combined with the electric contact theory and getting the main factors that including contact pressure,overlapping area,environment temperature,thickness of oxide film and electrical joint compound influences the contact performance;Secondly,with the single factor experiment to figure out influence of the every factors on the contact property of the copper busbar connector,and the mathematical model of contact resistance was summarized.Finally,in view of the copper busbar connector in current flow intensity of different sizes with various measured under the condition of contact resistance in both cases,the finite element simulation model is established by ANSYS Workbench software respectively lap surface heating effect of the research.The paper obtains the following results:(1)the proper contact pressure on the joint is significant to the copper busbar connector,and the contact resistance and contact pressure meet the rule of the negative exponential;(2)with the copper busbar has fixed-width,overlapping area is determined by the lap length,in this condition,the change of contact resistance is mainly because of the“streamline effect”,contact resistance and lap length follows the linear relationship;(3)the growth of the copper surface's oxidation film follows the laws of metal oxidation kinetics,the oxidation grows rate and ambient temperature are positive correlation,the oxide film growth along with the change of time,in turn,linear,parabolic and logarithmic law,with ambient temperature and the bolt tightening torque conditions,the contact resistance is negatively related to the thickness of oxide film,and finally summarized the contact resistance mathematical model with the factors of ambient temperature,oxidation time and the bolt tightening torque;(4)finite element simulation results show that the copper busbar connector current flow within the scope of rated always can meet the requirements of minimum temperature rise,but when the lap surface exist larger thickness of oxide film layer or coating of electrical joint compound performance has degradation,the temperature of connection area will exceed 30?,even exceed more than 50? when seriously;(5)when works in regular temperature environment,copper busbar connector lap surface coating without electrical joint compound compared with existing electrical joint compound,contact resistance increases slightly,however when works in 220? high temperature environment,during 0-40h period,contact resistance drops rapidly and in 40-250h period,contact resistance reduced lower than that of pure metal lap of resistance,because of the base oil evaporation and some chemical reaction occurred inside of electrical joint compound which lead to the degradation,after 400h contact resistance rising rate is accelerated,and finally at 500h,with the end of the high temperature test,connector's contact resistance increased by 3%.