National wire and cable product is suitable for large favorably rated voltage 500V and below for high tamper requirements and automated computer connection cable. Ground cable core computer cables computer cables must edge using K-type class B has anti-oxidant properties of low density polyethylene. Polyethylene insulation resistance of a high withstand voltage is good, small dielectric constant and loss temperature and variable frequency of influence is small, not only to meet the transmission performance requirements, but also to ensure the life of the cable. 1 [1] in order to reduce crosstalk and external interference between circuits, shielded cable structure. Cable shielding requirements are based on different occasions were used: combination of shielded twisted pair, shielded twisted pair cable consisting of twisted combination after total shielding and other methods. Shielding materials are round copper wire, copper, aluminum / plastic composite tape of three. Shield with the shield has good insulation properties of the cable in use shield, if shield potential difference between the right, it will not affect the signal transmission quality. When laying the ambient temperature of not less than: fixed laying -40 ℃, non-fixed laying -15 ℃ minimum bend radius: unarmored should be not less than 6 times the cable diameter cable with armored cable diameter should be not less than 12 times at 20 ℃ stable DC voltage 500V charging 1min test the insulation resistance should be not less than 2500MΩ · Km between each pair shielded twisted and shielded twisted pair between total shield should continue to route the cable core and the core of the shall be subjected to between room and shielded 50HZ, AC 2000V voltage test 5min without breakdown Hefei power cable through the National Electric Wire & Cable Co. /// large favorably