The voltage drop in the bus duct refers to the voltage drop between the phase line and the neutral line in the bus duct.When the load is concentrated at one end of the line,the load may be concentrated at different positions along the feeder line,evenly distributed along the feeder line or any similar field.The voltage drop of the load evenly distributed line is only half of that of the line with the same total load concentrated at the line end.When calculating the comprehensive load,it includes approximately uniform load segments and concentrated loads.We can regard the uniform load as a concentrated load segment at one end,take its voltage drop as half of the conventional voltage drop of the same total load,so that the load can be divided into many concentrated loads distributed at different distances along the line,and then calculate the voltage drop of the load carried in each segment.

　　The starting busbar unit is used to connect with transformers,distribution cabinets,and cables,and its current specifications are the same as those of linear busbar units.The busbar slot unit that cannot be plugged into the straight section busbar unit is designed to extend the distribution line.Bus ducts with sockets are used in conjunction with plug-in boxes.Configure according to the actual installation location of the device.The busbar terminal box is used to seal the termination end of the busbar trunking to ensure the power supply safety of the busbar trunking system.The plug-in box is used to transfer electrical energy from the busbar trunking to various floors of electrical equipment or high-rise buildings.The box is equipped with automatic air switches or deep fuses.According to on-site needs,the plug-in box can also be modified into a plug-in distribution box(without automatic air switches or fuses inside,only with sufficient capacity terminal posts).

　　The expansion busbar unit is used to absorb the axial variation of the busbar slot caused by thermal expansion.When the length of the busbar exceeds 80 meters,a section of expansion busbar is installed.The rated current of the expansion busbar unit is the same as that of the linear busbar unit,with a length of 1500mm.Variable diameter busbar units are used to connect different rated current units in the same system,making the entire busbar trunking system more economical and practical.Curved busbar unit,with four types of busbar joints including L-shaped,T-shaped,Z-shaped,and cross shaped,is used to flexibly connect the system.Its rated current is the same as that of the straight section busbar unit.When installing bus ducts along a plane in buildings of different shapes,it is advisable to choose bus ducts with rectangular shells.When installing along a curved surface,it is advisable to use resin cast bus ducts or cylindrical bus ducts.

　　Bus ducts have become an indispensable wiring method for electrical equipment and power systems in high-rise buildings,factories,etc.When selecting bus ducts,comprehensive consideration should be given to the usage environment,indoor dedicated clean areas,and IP30 or above levels.For places or outdoors with anti-corrosion requirements,fully enclosed resin cast bus ducts with IP68 rating shall be used.When the bus duct is installed horizontally and the bracket can be set as needed,a bus duct with a length of about 3m should be used.When the spacing between brackets is 6m or more,ultra long bus ducts should be selected.When the bus duct is installed vertically,it is advisable to use dense insulation or resin casting for the bus duct,and the insulation material should be suitable for long-term working temperatures not lower than 130℃.To avoid chimney effect,when using air insulated bus ducts,fire-resistant partitions should be installed between each unit inside the bus duct casing.