With the rapid development of China's economy and modernization construction,the load of electricity is increasing.In recent years,the use of bus ducts instead of cables has become a common phenomenon in developed countries,and China has also formed a development trend.However,due to the lack of understanding and knowledge of bus ducts among some users and quality supervision personnel,there are investment waste and hidden dangers in the project.According to the purpose of different places and the grade of the project,different types and technical parameters of bus ducts should be selected.

　　Bus ducts include fire-resistant busbars,fire-resistant busbars,fire-resistant smoke spreading busbars,and ordinary busbars.Fire resistant bus ducts are used for power supply of fire-fighting equipment and cannot be used for other purposes.Therefore,this type of bus duct has good heat resistance and insulation,and the heat energy of the bus duct cannot be dissipated,so it cannot be used at full load for a long time.Except for fire-resistant bus ducts,all other buses can operate at full load for a long time.The shell and insulation layer of the fire-resistant bus duct are made of fire-resistant materials with a high temperature resistance of≥1100℃and insulation materials with a high temperature resistance of≥300℃.The product has a fire-resistant time of 60 minutes,90 minutes,120 minutes,and 180 minutes.It will only burn when the temperature reaches 920-1050℃,and can operate at full load for more than 8 hours.

　　Fireproof busbars are generally enclosed in bus ducts or bus ducts with fire-resistant smoke spreading enclosures and fire-resistant partitions.Some enclosures are coated with fire-resistant coatings,which can transmit heat to the interior within the specified time.The bus ducts can operate normally,with a fire combustion temperature of around 800 degrees Celsius and a fire resistance time of 30 minutes,40 minutes,and 60 minutes,respectively.The fire-resistant smoke spreading busbar is usually flame-retardant,and in the event of a fire,the busbar in this section will not spread and burn to another section 2 meters away.Ordinary busbar trunking is not flame retardant,and in the event of a short circuit,it will continue to burn to other connected busbars,which can easily cause fire accidents.

　　There are two main types of bus duct structures:air type and dense type.The conductors between air type bus ducts are separated by insulation blocks;The phase conductors of the dense bus duct are tightly wrapped and pressed together with insulation material.Due to the absence of air in the middle of the dense bus,heat energy is directly transmitted and dissipated quickly,making it suitable for high current power supply.Air type bus duct has slow heat dissipation and is suitable for low current power supply.Bus ducts are superior to cables in terms of environmental protection,service life,and practicality,so bus ducts have become popular as a substitute for cable power supply.However,due to some manufacturers competing for market share at low prices without good product guarantees,and some engineering units not having a deep understanding of some technical parameters of bus ducts,there are hidden quality hazards in some projects.Therefore,the selection of bus ducts is crucial.