As the power supply busbar trunk with ordinary cable compared to show the strong advantages, but with the passage of time, the operation practice shows that the busbar itself there are many irreparable defects, so the busbar as the power supply products the ideal power supply is not the main line.
First, it is expensive, installation of large area, long installation period, labor intensity, and therefore a large investment. Plug type bus slot is expensive to be recognized, such as a three-phase four wire system, the height of 3M, the trunk current of 100A, with a branch connection of the plug-in busbar, the price of about $2000. The bus duct laying environment and installation requirements are special, in the building to set aside for the special electrical shaft, of a high-rise building, from the top to the bottom of the electrical shaft occupied area is considerable, increasing investment in civil engineering; busbar is a section of the installation, every day nearly one hundred kilograms, installed by human move and adjustment, the labor intensity is big because of the story, as can be imagined; different current levels are not the same, the busbar interchangeability is often poor, if the joint is not smooth, bolt tightening joint space is too small, the installation is more time-consuming; also the busbar installation more stringent requirements, the installation should avoid collision, strike, connecting bolts should be appropriate, tight too loose can cause problems, will also affect the service life of the bus slot, it will Experienced technical workers are required to complete the project.
Second, it is mostly made by hand, the product quality can not be controlled and guaranteed, and the joint is too much, there are many fault points, so the power supply reliability is poor. China's production of bus slot manufacturers, many in the southern provinces and cities, especially in Jiangsu, Yangzhong, can be described as the bridge, the rural bus bar. But in many manufacturers, can really do scientific management, high-quality production of the bus slot is not a few, the vast majority are shoddy. Bus slot production process backward, almost all manual operation, a lot of human factors, quality can not be effectively controlled. In order to make the production order, technical strength, quality of workers and the production environment, the construction unit should make a thorough and careful investigation on the production of the bus slot. Because of the insulation treatment in the space with an unclean, there will be some conductive particles in the insulation layer, there is no relationship between the initial operation, but a long time will cause insulation damage. In addition, some manufacturers in the name of new products, five core bus slot signs to mislead the majority of users. The so-called "five core bus slot" that PE line is also installed in the shell, not only high cost, inconvenient to use, and the specification is not allowed. Because the PE line must be continuous absolutely reliable grounding, too many joints are not allowed, and the five core busbar PE line must be a section of a connection, as long as there is a disconnect connector, the PE line will be charged, then the equipment shell connected with it may be charged, the danger of just as can be imagined.
Third, its moisture resistance, corrosion resistance is poor, laying environment and installation requirements are higher, and therefore maintenance workload. Busbar during transportation and storage, the insulation layer will damp metamorphism, copper will oxidation, corrosion, especially joint copper more susceptible to oxidation and corrosion, resulting in electrical performance degradation, so the busbar must be maintained before installation; busbar operation of heat insulation, heat discharge moisture, cooling and moisture absorption, will cause the insulation quality; loose and oxidation cold joint in heat, the contact resistance becomes large, joint heating. These facts are sufficient to show that busbar trunking must be maintained and maintained regularly. Long term use of busbar trunking at least once a year. Before maintenance, use the multimeter to measure the electric discharge of the bus bar to confirm that the bus is not charged. Check the following:
(1) check all fasteners and conductive parts of the contact loose;
(2) check whether the aging phenomenon of the insulation material and the melting phenomenon of the conductive part;
(3) check whether there is foreign body into the bus slot and whether there is water seepage.
Found problems to be dealt with in a timely manner, without leaving any hidden dangers. If there is an insulation breakdown phenomenon, should be broken down the bus slot or the use of pressure tester to check, find out the fault point, replace the new bus slot, or re dressing.
Fourth, the bus slot in the use of the contact parts or joints prone to heat, or select the bus carrying capacity of the bus will also cause insufficient heat. Therefore, in the practical design of the choice of the capacity of the bus slot, it is necessary to fully calculate the actual load of the building, and taking into account the impact of ambient temperature, but also with a margin.