The traditional protective grounding wire PE line is placed on one side of the enclosed bus duct shell grounding technology.Due to electromagnetic induction,the fault current induced on the protective grounding wire is 60%higher than calculated by actual measurement.At the same time,the distance between the three-phase conductive rows and PE is uneven,and the inductance is also uneven.When the line is long,the three-phase is severely unbalanced under fault current.The enclosure of the enclosed bus duct is made of aluminum magnesium alloy profiles,consisting of two side plates and upper and lower cover plates.The side plates are designed with heat dissipation fins and dovetail grooves,which not only facilitate the heat dissipation of the bus duct,but also enhance the rigidity of the enclosure and facilitate installation.At the same time,it reduces the weight of the bus duct,allowing for large-span design and reducing installation brackets.

　　The connection between the upper and lower cover plates of the enclosed bus duct shell and the side plates does not require screws,rivets,or welding,but instead uses hooks and grooves.Due to the lack of holes on the shell,water,gas,and dust cannot enter,which improves the protection level and has a very beautiful appearance.If the measures taken can ensure that the circuit has long-lasting good conductivity and the current carrying capacity is sufficient to withstand the grounding fault current flowing through the complete equipment,then the various metal components of the assembled equipment are considered to effectively ensure the continuity of the protective circuit.Using non-magnetic material aluminum alloy shell with good conductivity as the protective ground wire,it is surrounded by the conductive busbar.Due to its proximity to the three-phase busbar as much as possible,it can achieve low reactance,and the distance between the protective ground wire and the three-phase busbar is equal,with the same reactance.

　　Whether it is a short-term or continuous relative ground short circuit fault,this grounding method is better than setting up a separate PE busbar.Therefore,the International Electrotechnical Commission has announced and advocated the use of enclosures as grounding conductors for electrical busbars(bus ducts).Integrating the shell with PE also avoids poor grounding continuity at the connection between the shell and PE due to long-term corrosion and poor contact.Therefore,the overall grounding technology using the shell as the PE row is an effective and reliable insulation method.There is an insulation layer on the conductive busbar,and there is a certain air gap between the phases.There is also an insulation pad made of DMC material pressed between the conductive busbar and the shell,with triple insulation to ensure the insulation of the bus duct is foolproof,especially when used in humid environments,which shows its superiority.

　　The aluminum profile shell has much better anti-corrosion performance after anodizing for 10U and galvanizing.Long term atmospheric exposure tests on different grades of aluminum alloy sheets and galvanized copper plates in Japan show that the corrosion depth of the former is about one twentieth of that of the latter.Now there is a high protection level IP54,which solves the waterproof problem.Beijing Taifeng has adopted domestic IP54 bus ducts.The length of straight bus ducts is limited by transportation capacity,but their design and production capacity are not limited by length,which can meet the needs of engineering,especially modern factories,for large-span bus ducts.Due to its good rigidity,hangers can be omitted between spans of 6 meters.