Traditional bus ducts are facing challenges from cables,especially branch cables.Years of practical experience have proven that both have their own advantages in product performance,application areas,and economic costs.With the changing times,busbar trunking systems have gradually been introduced and developed,and have quickly been widely applied in construction projects.It has unique performance advantages compared to traditional transmission equipment,such as high current carrying capacity,strong overload capacity,convenient tapping,good heat dissipation,and easy maintenance.

　　Ordinary bus duct is a transmission and distribution system with electrical continuity formed by wrapping several conductors in a metal shell through a reasonable and safe structure.Ordinary bus ducts are generally divided into two types:dense insulation type and air insulation type.Air insulated structure is simple and capable of carrying large currents;The dense insulation structure is compact and has good heat dissipation capability.They all have the characteristics of strong overload capacity,convenient tapping,and small space occupation.Cables are divided into single core cables and multi-core cables.Single core cables mainly use various insulation materials to wrap multiple strands of copper wire inside the insulation layer as a current conductor for a certain phase.A multi-core cable is a complete cable formed by twisting multiple insulated wire cores together and wrapping them with an outer sheath.

　　Whether it is cables or bus ducts,the overload capacity depends on the operating temperature of the insulation material used.The working temperature of bus duct insulation material is 105℃,and radiation cross-linked flame-retardant winding tape(PER)and radiation cross-linked polyolefin heat shrinkable tube with working temperature above 140℃have been developed.At present,the normal working temperature of insulation materials used in cables is generally 90℃and 105℃,while the high working temperature of irradiated cross-linked cables is 125℃.Therefore,the overload capacity of bus ducts is much greater than that of cables.Bus ducts generally adopt plug-in installation and tapping methods.The so-called plug-in bus duct is to use the method of plugging to connect the power supply of the main line to the branch line,leaving a plug-in box every few meters,so the tapping is very convenient.

　　The cable needs to be tapped on site,which has poor reliability.Even prefabricated branch cables have their own defects.The obvious disadvantage of branch cables is that they require customized branch connection equipment from the factory,usually using open"C"type clamps.After a long time,whether this kind of hoop can ensure the tightening force is also a problem.When installing branch cables,it is necessary to cut off the floor power supply,while when installing bus ducts,there is no need to cut off the power.Just remove the plug-in box of the bus duct under no-load conditions.But it is very dangerous to cut off the branch power supply of the prefabricated branch cable while it is live.The maintenance of bus ducts is relatively simple.During daily maintenance of bus ducts,it is usually necessary to measure the temperature rise of the shell 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.If high-strength bolts of grade 8.8 are used,they do not need to be reinforced regularly.