Due to factors such as the resistance of conductors and the AC current meter effect when multiple conductors approach each other,heating can occur when current passes through the bus duct.The allowable temperature for heating during long-term operation of copper and aluminum bare bus ducts is 70℃,but when there is a reliable tin cover on their contact surface,the allowable temperature can be increased to 85℃.Due to the limitation of the allowable temperature for continuous heating,bus ducts of different materials and sections provide corresponding long-term allowable current values.When selecting the section of the bus duct,the actual long-term operating current of the bus duct should be lower than the long-term allowable current value of the selected section of the bus duct.

　　In situations where the average annual load is high and the conductors and bus ducts are large(such as outdoor distribution equipment bus ducts),the bus ducts are usually selected using the economic current density method.Bus duct is a conductor that connects the various current diversion branch circuits in an electrical device together.It is the carrier for collecting and distributing power,also known as a bus duct.The conductors of the current carrying branch circuits in each distribution unit are commonly referred to as bus ducts,which are used to collect,distribute,and transmit electrical energy.During operation,there is a huge amount of electrical energy passing through the bus duct.

　　When the bus duct is short circuited,it is subjected to significant heating and electrodynamic effects.Therefore,it is necessary to select the bus duct material,cross-sectional shape,and cross-sectional area reasonably to meet the requirements of safe and economical operation.The heat source affected by the temperature rise of the bus duct system is the cone screw strip mixer.The cone screw strip mixer is checked for foreign objects entering the interior of the bus duct,and the components of the bus duct system are checked for defects,rust,and whether the bracket springs have appropriate elasticity.If any problems are found,they should be replaced immediately.Bus duct is divided into main unit,feeding unit,tap unit,variable diameter unit,expansion unit,various bending units,etc.

　　Busbar trunking is a busbar system composed of metal plates as protective shells,conductive bars,insulation materials,and related accessories.It can be made into plug-in enclosed busbars with plug-in junction boxes at regular intervals,or into feeding enclosed busbars without junction boxes in the middle.In the power supply system of high-rise buildings,the power and lighting lines are often set separately,and the bus duct is installed vertically along the wall in the electrical shaft as the main power supply line.Copper bars or aluminum alloy bars are generally used as conductors for bus ducts.To prevent oxidation on the surface of the bus bar,tin plating or silver plating is applied to the surface of the bus bar.