At present, domestic enterprises that produce low-voltage aerial bundled cables are based on the national standard GB∕T 12527-2008 “Overhead insulated cables with rated voltage of 1kV and below”. This standard is the latest edition of the national standard revised and revised in 2018.
Overhead insulated cables are mainly used in places such as overhead fixed installations and draw-in cables, and their insulation materials are made of special overhead insulated cable materials for weather resistance. Therefore, the overhead insulated cables have a simple structure, safety and reliability, excellent mechanical and electrical properties, and environmental resistance. The advantages of ultraviolet rays, due to its insulation using weatherproof special overhead insulated cable material, the long-term allowable working temperature of the cable up to 70 °C or 90 °C, and excellent electrical insulation properties, volume resistivity of 1.0 × 1012Ω · m or more; in laying, The use of overhead insulated cables can reduce laying gaps, save line corridors and reduce voltage drop. In use, it can reduce the occurrence of power supply accidents and ensure personal safety.
At present, domestic companies produce BLX cables, which are mainly based on JB/T1601-1993 "Rated Voltage of 300/500V Rubber Insulated Fixed Wires". This standard was issued in 1993 and has not been updated in the past 20 years. The product is on the market. Has been gradually replaced by aerial cables.
BLX type rubber insulated fixed laying wire is suitable for electrical equipment and lighting system with AC rated voltage Uo/U of 300/500V and below. Its long-term allowable operating temperature is 65°C. Its structure is aluminum conductor, extruded rubber insulation, external braided wire and then greased asphalt material, greased asphalt material function is anti-ultraviolet. Before and after the cable is used for two years, the woven glass yarn is often detached and damaged due to wind and sun exposure, resulting in short service life, poor anti-aging properties, and environmental pollution.
With the continuous update of national standards for cable products, according to the national requirements for safe and reliable electricity use, BLX type fabric wires are inferior in performance to overhead cables, so overhead insulated cables on the market have gradually begun to replace BLX type cables.