一级特黄a视频_色即是空之甜性涩爱_麻豆制服丝袜诱惑_男女爱爱免费超爽大片黄_国产熟女大声叫受不了视频_国产免费网站在线看大片_一区二区三区自拍偷拍视频_91精品蜜臀国产_免费午夜福利影片在线观看_午夜福利成人在线播放

The core of the cable is mainly composed of core wire, core insulation, cable insulation, cable ties, tape layer and so on. 

1, Wire material: An annealed soft copper wire is used. According to the communication service range and user distribution The use of different diameter and different logarithmic cable 

2, wire insulation: the use of solid polyethylene, foam polyethylene, foam / solid leather polyethylene and other different insulation structure, mainly to improve the performance of the cable to adapt to different uses Cable needs. Often the insulation is required to be uniform and continuous, without bleaching, smooth and rounded surfaces. 

3, core twist: In order to reduce the cable between the crosstalk between the circuit and the electromagnetic coupling coefficient, determined by the mutual position between the core, that is, twist pitch. So the whole plastic cable with more than 20 kinds of pitch. 

4, the cable core structure: the core twisted into pairs (or group), and then a number of pairs (or combination) 

5, cable core package: the use of polyester, polypropylene, polyethylene or nylon and other composite materials, Non-hygroscopic, dielectric, thermal insulation properties, generally white, overlapping package in the cable outside the heart.