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.The surface treatment of the enclosed busbar trunking shell is an important task,which includes processes such as acid washing,phosphating,drying,powder coating,and curing.The shell coated with polyester epoxy powder has strong surface adhesion and can maintain insulation for a long time.The enclosed busbar trunking is a busbar system composed of metal plates as the protective shell,conductive bars,insulation materials,and related accessories.

　　The application of enclosed busbar trunking is in low-voltage,high current power supply and distribution systems,usually installed in electrical shafts,using a single central busbar system to supply and distribute power to each floor.The enclosed busbar trunking system can be composed of various busbar units.Linear busbar units are used to extend power supply and distribution lines,and enclosed busbars with tap changers are used in conjunction with plug-in boxes to distribute power loads.The starting busbar unit is matched with the starting incoming box to form the connection component between the busbar and the cable.The starting busbar unit can also be connected to transformers or distribution cabinets.

　　The expansion busbar unit is used to absorb the axial variation of the busbar caused by thermal expansion.When the length of the busbar exceeds 80m,a section of expansion busbar unit should be installed.Variable diameter busbar units are used to connect different rated current units in the same system,in order to make the power supply of the entire busbar system more economical and reasonable.There are four types of busbar bending connection units:L-shaped,T-shaped,Z-shaped,and+shaped.They are used for connecting and changing the direction of horizontal and vertical power supply and distribution,and can flexibly connect busbar systems.The busbar terminal box is used for the termination end of enclosed busbars to ensure the power supply safety of the busbar system.

　　The plug-in box is used to lead out power outlets on enclosed busbars.The plug-in box is equipped with an automatic air switch for cutting off and connecting power.The enclosed bus duct conductive copper busbar is composed of pure copper busbar,and the surface of the conductive copper busbar joint should be uniformly tinned or silver plated;The insulation material is composed of high-strength insulating plastic blocks made of polytetrafluoroethylene and polycarbonate.Bus ducts 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.