National standard and industry standard of wire and cable
In the process of compiling national and industrial standards, many contents refer to UL standard or en / IEC standard. However, due to the multi reference, some statements are not accurate. For example, in GB / t32129-2015, JB / t10436-2004 and JB / t10491.1-2004, the temperature resistance grades of materials and wires are 90 ℃, 105 ℃, 125 ℃ and 150 ℃, which obviously refers to the standard system of UL. However, the expression of heat resistance is the allowable long-term operating temperature of conductor. The expression of heat resistance is obviously referred to IEC standard system.
In IEC standard system, the long-term working temperature of conductor should be related to the design life of cable, but there is no expression of cable life in these national and industrial standards. Therefore, the statement that "the applicable long-term allowable operating temperature of cable conductor is 90 ℃, 105 ℃, 125 ℃ and 150 ℃ remains to be discussed.
Can the silane crosslinked XLPE reach the temperature resistance grade of 125 ℃? The more rigorous answer should be that the silane crosslinked XLPE can reach the rated temperature of 125 ℃ specified in UL standard, because it has been clearly proposed that the chemical composition of the material should not be specified in Chapter 40 of ul1581. However, whether the XLPE conductor can reach 125 ℃ for a long time is related to the design life and application situation of the cable. At present, no relevant information has been found to systematically evaluate the service life of the material. Based on the short-term aging, if the design life of the cable is 25 years, the long-term temperature of the conductor allowed is certainly greater than 90 ℃.
In the IEC standard, the long-term working temperature of the design conductor of traditional power cable, building line and even solar power cable will not exceed 90 ℃, but it does not mean that the allowable long-term working temperature of the materials used for such cables cannot be greater than 90 ℃. It can not be said that the radiation crosslinking material can reach the temperature resistance grade of 125 ℃, while the silane cross-linking material can not reach the temperature resistance grade of 125 ℃. This statement is unreasonable.