The current carrying capacity is a very important performance for both bus ducts and cable trays.When cables are laid inside the tray,according to relevant regulations,the capacity reduction factor is 0.7,and the current carrying capacity is only 400A.This current can only meet the requirements of small capacity transmission lines,while bus ducts have a large current carrying capacity with various specifications of current values,up to 8000A,which can fully meet the requirements of transmission lines.There are many advantages to using bus ducts,which are widely used in low-voltage distribution system transmission mainline projects and are increasingly replacing cables.

　　Compared with cables or pre branch cables,bus ducts have the characteristics of good heat dissipation,low impedance,and high current carrying capacity.Compared with the technical performance of cables or pre branch cables with a current carrying capacity of 630A or above,bus ducts with a current carrying capacity of 630A or above can save 10-35%of copper materials and reduce energy loss by more than 15%under the same current carrying capacity.There are fewer circuits in the bus duct,which can reduce the number of accident points.And there are many circuits with single cable laying,which increases the number of accident points.From an aesthetic perspective,the advantage of busbar trunking is that its linear structure is simple and clear,while it has multiple cable lines and a complex structure.Bus ducts can provide protection for loads,while cables cannot provide protection for loads.

　　The space requirement for bus ducts is not very high.The load that a single bus duct can bear can reach 6000a,while if cables need to reach 6000a,multiple cables need to be laid in parallel.The lifespan of bus ducts can reach 30-60 years,while cables only have a lifespan of 10-15 years.The installation of bus ducts is simple and convenient,while cables require the installation of cable trays.It is more complicated and requires more materials to fix the cables after fixing the trays.Bus ducts have good heat dissipation performance,and the insulation materials of cables(core insulation and outer insulation)are both insulation materials and thermal insulation materials.Therefore,when laying power cables in cable trays,it is allowed to lay two layers more,because heat dissipation is considered.

　　The busbar duct utilizes air conduction for heat dissipation and dissipates heat through a tightly contacting steel casing,thus its heat dissipation performance is comparable to that of cables,and the cable heat dissipation performance is evident.Bus ducts require almost no maintenance,and daily maintenance usually involves measuring the temperature rise of the casing and core bolts,as well as the temperature rise of the joints in the incoming box.If the core bolts are of grade 4.8,they need to be tightened regularly,while if high-strength bolts of grade 8.8 are used,they do not need to be reinforced regularly.Due to factors such as easy wear and tear,aging,and short lifespan,cables require regular inspection,maintenance,and even replacement.Therefore,in summary,there is still a significant difference between bus ducts and cables.