First generation
Air type
Since the mid-1950s, represented by Beijing Baizhifang Airport Electrical Appliance Factory, the conductive row was supported in the shell with insulating gaskets and insulated by the air medium. The interphase distance is 50mm.
Second generation
Intensive type started in the mid-1980s, represented by Zunyi Long March Electrical Control Equipment Factory, where the conductive bars were covered with insulating materials and then fastened together on both sides. Insulation material: PTFE tape, working temperature is 200 degrees, the disadvantage of high temperature decomposition produces lethal poison gas (octafluoroisobutylene and fluorophosgene)
The quality of PVC heat-shrinkable tubes varies greatly. Some manufacturers use cheap products, and the measured insulation cannot reach Class B. Irradiation cross-linked flame retardant tape (PER) has a good effect, the working temperature is 150, the waterproof performance is good, it is elastic, and the wrapping is relatively tight. A special busbar form produced in the evolution of the second-generation busbar is the dense busbar air socket. Due to changes in the process, it has basically become a dense busbar-intensive socket, that is, an overall dense busbar.
Third Generation
In addition to the insulating layer of the conductive bar itself, the composite insulated busbar also has a certain air dielectric insulation between the phase lines. Vulcanized insulation technology is used in various elbows. The straight section adopts MT-7-3 rubber sleeve. Vulcanized insulation technology: The material is CZ260 fast-solid insulation powder, which is cured by quaternary cross-linking, and there is no gap between the insulation layer and the conductive row. Its heat dissipation performance, moisture resistance and insulation reliability are excellent. However, due to the higher cost than the second-generation bus, it has not been widely promoted.
Other related situations: 1. According to the results of national supervision and spot checks in 1995 and 2000, the qualified rate of domestic busbars increased from 57.14% to 71.4%. 2. Busbar welding: L-shaped (flat bend) and T-shaped busbars are all used The busbar is welded, but there is no relevant standard in the national standard. It is said that the use of weld flaw detection (according to the GB3323 level III standard) is being considered. Shanghai Waigao adopts domestic IP68 outdoor busway. 4. The advantages and disadvantages compared with cables are simply the difference between trunk-type power supply and radial power supply.
