Analysis Of Thermal Characteristics And Research On Method Of Temperature Protection Of Enclosed Busbar

In recent years as the power transmission equipment enclosed busbar has been widely used in transformer substation, high-rise buildings and factory buildings, to replace traditional cable distribution. Because of enclosed busbar characteristics, its performance and reliability are influenced by temperature, especially the connector of enclosed busbar. The connector of enclosed busbar is connected by bolt. If the bolt is not tightened, or even tightened, connector loosening and contact resistance increasing are caused by thermal expansion and contraction of the connector through running.At present, many research results of thermal characteristics of enclosed busbar straight segments have been obtained by domestic and foreign scholars. But enclosed busbar connectors of thermal characteristics have been not studied. Existing protection methods in low voltage distribution system can not protect a small current which does not meet the setting action value of electrical protector,of high temperature which exceeds the normal current heating at the moment.Considering the conservation of energy based on simplified enclosed busbar connector model in this paper, the mathematical model of temperature field of busbar connector is established. Based on the model, measures of reducing connector temperature are given. With the current methods of protection in low-voltage distribution system, thermal protection method is given for overheating, especially the connector of a small current high temperature.â‘ Considering three basic modes of heat transfer heat conduction, convection and radiation based on simplified enclosed busbar connector model, the mathematical model of temperature field of busbar connector is established. The finite volume method on the temperature field of busbar connector is used to establish the discrete equations. Tridiagonal matrix method is used to solve the temperature distribution inside and outside the enclosed busbar connector. The experiment validates the correctness of the model.â‘¡With the three methods of heat transfer conduction, convection and radiation based on the mathematical model established of the temperature field, temperature rise is caused by various factors,for example, current, conductor material, insulation material, ambient temperature, the shell convection coefficient, the shell surface and contact resistance. All the factors are analyzed and reducing the temperature measures are given.â‘¢The protection defects of short-circuit protection, overload protection and earth fault protection already existed are analyzed in low-voltage distribution system using enclosed busbar at present. With the current methods of protection in low-voltage distribution system, thermal protection method is given for overheating, especially the connector of a small current high temperature.