Due to the different locations where bus ducts are used,there are currently air insulated,compact insulated,reinforced(double-layer insulated combination of air and compact),socket insulated,and epoxy insulated types.The wiring of air insulated lighting bus ducts is convenient,with a wide control range and flexible adjustment,solving the disadvantages of centralized lighting,long control lines,and high voltage drop losses in large factory buildings.Reinforced busbar trunking is suitable for power distribution of equipment in general large factories.It has a large-span busbar trunking,which can not only reduce installation points and busbar trunking connection points,but also correspondingly reduce the fault points caused by it,especially suitable for welding workshops and stamping workshops with high impact currents.

　　The socket type bus duct is suitable for small precision equipment workshops,laboratory display centers,and other places.It can be equipped with a single-phase socket distribution port and used as a power supply for small assembly lines.It is easy to install,beautiful,and convenient to use.Epoxy insulated busbar trunking is suitable for places that require anti-corrosion and waterproofing.The insulation methods of bus ducts include wrapping,heat shrink,electrostatic adsorption,or a combination of wrapping and heat shrink,etc.The mechanical processing of bus ducts requires high precision,strong interchangeability,and easy assembly and disassembly.During installation,it is required to be able to be easily inserted.The connection head of the bus duct is crucial,requiring high machining accuracy and good interchangeability of the connection head,and must meet the requirement of low contact resistance;Can automatically eliminate damage caused by thermal stress;Easy to assemble and disassemble,its basic structure is that when in single-sided contact,the contact surface is very smooth and does not press any bumps,and a single screw connection is used.

　　The large capacity bus duct adopts parallel double screws or parallel triple screws,with butterfly washers at both ends for locking.The tightening torque is specified and the contact pressure should be kept constant to automatically eliminate thermal stress.The rated capacity of the busbar trunking is selected based on temperature rise to achieve safe operation,sufficient service life,and reliable operation.The cross-sectional area of the wire is not used as a criterion for judging the busbar trunking.The busbar trunking seems to have sufficient cross-sectional area,but there may still be a risk of high temperature rise.The prominent limiting factor in the working life of well-designed bus ducts is the gradual thermal aging of their insulation.For every 10℃increase in working temperature,the insulation material life is shortened by about half.

　　The busbar in the bus duct may be subjected to considerable electromagnetic force when short-circuit current occurs.The force generated per unit length of busbar is proportional to the square of the short-circuit current and inversely proportional to the distance between busbars.When the system in which the bus duct is located has a lower power factor or protective devices have a longer clearing time for short circuits,the short-circuit capacity must be reduced.The possible short-circuit current is used to determine the required short-circuit current capacity,and the short-circuit capacity of the bus duct must be equal to or greater than the possible short-circuit current.The short-circuit capacity is related to many factors,such as the center spacing of busbars,the size and strength of busbars,and mechanical supports.The short-circuit capacity should include the ability of the grounding circuit channel to pass the rated short-circuit current.If the grounding circuit channel cannot fully pass through this current,arcing and sparks may form at the junction,accompanied by fire hazards.