双屏蔽即两层屏蔽层，先分屏蔽后总屏蔽，也有双总屏蔽电缆但是作用不大，一般采用先分屏蔽后总屏蔽的居多。
Double shield is two layers of shielding layer, the first shielding after the total shielding, also have double the total shielding cable but little action, generally use the total shielding shielding are first after.
如图：计算机电缆，型号为DJYPVP，根据型号可看出是双屏蔽电缆，线芯绞对组铜丝编织屏蔽，总包带和总屏蔽包带之间屏蔽层有编织的和金属绕包的两种。
Figure: computer cables, type DJYPVP, according to the model we can see that the double shielded cable, wire core stranded on the group of copper wire woven shielding, shielding bag with general contractor and between the shielding layer has two kinds of weaving and metal around the bag.
屏蔽电缆有单层屏蔽和双层屏蔽之分。双层比单层的好，比双绞屏蔽电缆性能更优异的是铠装型双绞屏蔽电缆。
Shielded cable with single-layer and double-layer shielding of shielding. Double layer of good, performance is more excellent than shielded twisted pair cable is sheathed type shielded twisted pair cable.
所谓双屏蔽电缆是指有两层屏蔽层、且两层屏蔽层之间必须有绝缘隔离的电缆！如两层屏蔽层之间不彼此绝缘（相互导电）,只能视为一层屏蔽！屏蔽层应具有良好的接地，如果不接地因为屏蔽层面积大，有很大的寄生分布电容，将产生寄生耦合干扰。
The so-called double shielded cable refers to must have the cable insulation isolation between the two layers of shielding layer, and the two shielding layer! As between the two layers of shielding layer is not insulated from each other (are conductive), can only be regarded as a shield! The shielding layer should have good grounding, if not grounded because of shielding layer area, a parasitic distributed capacitance greatly, will produce the parasitic coupling interference.
根据《GB50217-2007电缆设计规范》、《GB50057-94建筑物防雷设计规范》等相关规定：单层屏蔽应采用一端等电位接地；双层隔离屏蔽的内层应采用一端接地，外层则应两端接地。
According to the "GB50217-2007", "GB50057-94 cable design code of building lightning protection design code" and other related provisions: monolayer shield should be grounded by the end of the equipotential shielding; inner layer should use the end is grounded, the outer layer should be grounded at both ends.
如铠装型双绞屏蔽电缆（常用的型号规格：ASTP-120Ω（for RS485 & CAN） one pair 18 AWG）就是属于双屏蔽电缆的一种，其内屏蔽是编织屏蔽网+铝箔，外屏蔽则是钢带铠装层，内屏蔽和外屏蔽之间还有一层绝缘隔离层。使用时，钢带铠装层两端接地，*内层屏蔽一端接地！可用于干扰严重、鼠害频繁以及有防爆要求的场所。
Such as armored shielded twisted pair cable (model: common ASTP-120 omega (for RS485 & CAN) one pair 18 AWG) is a kind of belongs to the double shielded cable, the inner shield is braided shielding net + aluminum foil, the outer shield is a steel tape armoring layer between the inner shield, and an outer shield and a layer of insulating layer. When in use, a steel tape armoring layer grounded at both ends, one end of the inner shield grounding! Can be used for interference, frequent and serious pest in places with explosion-proof requirements.