General wires and cables are insulated with plastic and rubber sheaths. These materials are conventional engineering materials with abundant sources, which can meet the requirements of mass production, and the cost is relatively low.But for some special industries such as petrochemical, steel, aerospace, shipbuilding, war industry, pharmaceutical, food, plastics machinery, boilers and other industries related to the heat and high temperature, all need to be able to bear certain high temperature wire and cable, ordinary wire and cable obviously cannot use, need to be capable of high temperature wire and cable to ensure the safe operation of the power and signal.
Along with our country economy fast development, the special industry demand for high temperature cable has been rapid growth phase, heat resistant and high temperature cable is growing at 20% a year, high temperature cable as an important part of special cable, have extremely strong vitality, in short supply, China imported about two billion yuan a year for domestic construction.
The general requirements of the International Electrotechnical Commission (IEC) for grades of heat resistance of insulation are as follows:
Heat resistance grade YAEBFHC
Very high allowable working temperature /℃90105120130155180≥180
The insulation and sheathing for electric wires and cables used in our industry are made of common engineering rubber and plastic as the basic resin, but they are required to be of insulation grade.Common rubber materials for cables are: butadiene rubber, ethylene propylene rubber, natural rubber and chlorosulfonated polyethylene, etc., the working temperature is (60 ~ 75) ℃;Common cable plastic materials are POLYvinyl chloride, polyethylene (including crosslinked polyethylene) and polypropylene, etc., the working temperature is (70 ~ 90) ℃.Thus, these cables are not strictly heat-resistant or high-temperature cables.
Heat resistant cable generally refers to (90 ~ 155) ℃ and below the cable, and high temperature cable is 180℃ and above the cable.To solve the problem of high temperature resistance of ordinary cables, it is necessary to improve the material, or the use of high temperature resistant insulation class materials.