The main drawback of enclosed busbars is the difficulty in ensuring sealing,and the quality of sealing directly affects the insulation performance of the busbar,which in turn affects the normal operation of the busbar trunking.There have been multiple accidents in China caused by poor sealing of enclosed busbars,and the leakage problem of enclosed busbars during previous installations has not been completely resolved.

　　Each section of the enclosed busbar consists of three parts:the outer shell,the conductor,and the insulator.The outer shell and the conductor are relatively fixed in position through the insulator.In order to achieve good sealing of the enclosed busbar,the contact surface between the insulator base and the aluminum cover plate of the base is tight,and a circular rubber gasket is added between the two contact surfaces.The conductor is supported by three pillar insulators located at 120°angles to each other on the same section.The intersection of the insulator axis coincides with the center of the conductor and the shell,and the pillar insulators are fixed to the shell with bolts.The enclosed busbar is connected segment by segment to form a complete enclosed busbar.Due to the large number of post insulators and the high mobility of insulating bullet blocks,coupled with long-distance transportation vibrations causing the enclosed busbar structure to loosen,the probability of leakage at the insulator fixing screws increases.

　　Due to the fact that most of the connections of the enclosed busbar are made through welding,and the outer shell of the enclosed busbar is made of aluminum,the aluminum plate is prone to react with oxygen,generating a dense and difficult to melt oxide film on its surface.The specific gravity of the oxide film is also high,making it difficult for it to float out of the molten pool and form weld slag inclusions;In addition,liquid aluminum can dissolve a large amount of hydrogen gas,while solid aluminum hardly dissolves hydrogen gas.Therefore,when the melted weld metal is rapidly cooled and solidified,hydrogen gas cannot be released in time,and it is easy to accumulate and form pores in the weld seam;Factors such as humid welding environment can also affect the sealing performance of the welding joint.Due to the loose connection of the inflation pipeline,there is also a certain degree of leakage in the connection between the inflation pipelines of the enclosed busbar micro boosting device and the interface with the enclosed busbar.

　　Closed busbars can cause various deformations during long-distance transportation.After opening the enclosed busbar duct,the enclosed busbar should be inspected first.For the undeformed busbar,it should be directly put into leak detection and installation state.For the deformed enclosed busbar,it should be calibrated according to quality requirements.After passing the inspection,segmented leak detection should be carried out.Aluminum is highly reactive with oxygen and can only be welded using inert gas shielded arc welding.To ensure welding quality,busbar welding work must be carried out by qualified argon arc welders who have passed the examination.Before welding,samples should be taken for trial welding,and then photographed for inspection.Only after passing the inspection can formal welding be carried out.