Dense insulated bus ducts can be used for AC three-phase three wire,three-phase four wire,three-phase five wire systems,with a frequency of 50-60HZ,a voltage up to 400V,and a rated working current of 250-5000A.They are mainly used as new power supply and distribution equipment in industrial and mining,enterprises,and high-rise buildings.The bus duct with a socket can be easily connected to the power supply branch through a plug-in head box or a plug-in switch box.Bus ducts have the advantages of small size,compact structure,high transmission current,and easy maintenance.The installation of busbar trunking can be directly connected from the transformer to the low-voltage distribution cabinet,or directly connected from the low-voltage cabinet to the distribution system as a distribution main line.

　　The bus duct ensures long-term normal operation in these environments,with an altitude not exceeding 2000M;The ambient air temperature is between-5 and+40℃,and its average temperature is not higher than+35℃within 24 hours;The air is clean,with a relative humidity not exceeding 50%at temperatures as high as+40℃,and allowing for higher relative humidity at lower temperatures;For example,at+20℃,it is 90%,but it should be considered that due to temperature changes,there may be occasional moderate condensation;The pollution level is level two;Installation categories are III and IV;The installation method is specified in this user manual.It is recommended to use the fixing method shown in Figure 3 for the busbar trunking in the transformer room.

　　Use a channel steel bracket to support the bus duct,and use round steel as a hoop to fix the bus duct on the channel steel bracket.The two ends of the channel steel bracket are connected to the embedded parts on both sides of the transformer room wall with bolts.In this way,the"rigidity"fixation of the channel steel bracket and the"flexibility"connection of the expansion joint are fully matched,and the"combination of steel and flexibility"ensures that the low bushing of the transformer will not be damaged under stress.The busbar trunking is generally lifted with round steel,which is not suitable for fixing the busbar trunking in the transformer room because this lifting and fixing method is"flexible"and can only lift the busbar trunking so that it cannot move up and down.When the busbar trunking is improperly installed and subjected to torsional stress or short-circuit electric force,it may shake left,right or up,which will cause damage to the low-voltage bushing of the transformer connected to the busbar trunking or oil leakage at the rubber sealing ring at the root of the bushing.

　　The expansion joint is used as a transitional connection between the bus duct and the transformer.However,due to the use of bus duct as the main busbar for low-voltage incoming lines,the current is generally high,some have reached 2500A,and the corresponding expansion joint has a larger cross-section and smaller elasticity,which may still cause stress on the low-voltage sleeve of the transformer.Insulated bus duct has the advantages of small volume,compact structure,high transmission current,safety,and easy maintenance.It has been widely used in low-voltage distribution equipment of enterprises.However,during the construction management process,it was found that due to the monotonous product specifications of the manufacturing plant,overly simple installation and use instructions,and inadequate design considerations,on-site installation is often difficult.