1. metal shielding control cable grounding, shall comply with the following provisions:

    ①. 计算机监控系统的模拟信号回路控制电缆屏蔽层，不得构成两点或多点接地，应集中式一点接地。

1. Analog signal loop of computer monitoring and control system of control cable shielding layer shall not constitute two or more points should be centralized grounding, grounding point.

    ②. 集成电路、微机保护的电流、电压和信号的电缆屏蔽层，应在开关安置场所与控制室同时接地。

. the cable shielding layer of integrated circuit, microcomputer protection and current and voltage signals, should be in place and at the same time switch control room ground.

    ③. 除上述情况外的控制电缆屏蔽层，当电磁感应的干扰较大时，宜采用两点接地；静电感应的干扰较大时，可采用一点接地。双重屏蔽或复合式总屏蔽，宜对内、外屏蔽分别采用一点、两点接地。

. the control cable shielding layer in addition to the above, when the electromagnetic induction interference is larger, should adopt two grounding points; electrostatic induction interference is large, the grounding point. Double shielding or composite shielding, the internal and external shielding should be used one point and two points respectively.

     ④ .两点接地的选择，还宜在暂态电流作用下屏蔽层不被烧熔。 

4. Two point to ground, also should be shielded in the role of transient current layer is not melted.  

     ⑤. 强电控制回路导体截面不应小于1.5mm2，弱电控制回路不应小于0.5mm2。

The electrical circuit control section. The conductor shall not be less than 1.5mm2, the weak control loop should not be less than 0.5mm2.

2.控制电缆金属屏蔽为什么要接地： 

Why should the metal shielding control cable grounding: 2.

      金属屏蔽层最在电缆屏蔽接地是为防止电气设备因受电磁干扰造成误动和危害，为避免电磁干扰，控制电缆的屏蔽层均应接地。

Metal shielding layer in the cable shield grounding is to prevent electrical equipment due to electromagnetic interference caused by misoperation and harm, to avoid electromagnetic interference, shielding control cable shall be grounded.

屏蔽电缆的屏蔽层两端接地使电磁感应在屏蔽层上产生一个感应纵向电流，该电流产生一个与主干扰相反的二次场，抵消主干绕场的作用，显著降低磁场耦合感应电压，可将感应电压降到不接地时感应电压的1%以下。当然屏蔽电缆的屏蔽层两端接地也存在以下两个情况：

The shield cable shield grounded at both ends of the electromagnetic induction to generate an induction current in the longitudinal shielding layer, the current one opposite the main interference in the two field, the main offset around the field effect, significantly reduce the magnetic field induced voltage, the induced voltage drop to ground when the induction voltage of 1% the following. Of course, there are two cases in which the shielding layer of the shielded cable is grounded at both ends.

      ①、当接地网上出现短路电流或雷击电流时，由于电缆屏蔽层两点的电位不同，使屏蔽层内流过电流，会引起额外的冲击或干扰电压。

1, when the ground appeared on the short circuit current and lightning current, the potential of two different cable shielding layer, the current flowing through the shielding layer, can cause shock or additional disturbance voltage.

      ②、当屏蔽层内流过电流时，对每个芯线将产生干扰信号。但对应用于继电保护和自动装置回路的屏蔽电缆，由于其输入和输出均型槽模具 一次性止血带 保定水处理设备 一次性止血带 保定空压机 北京真空泵有一端在电网的高压或超高压环境中，电磁干扰是主要因数，为防止暂态过电压，故电气继电保护和自动装置的电缆屏蔽层宜在两端接地。

II, when the current flowing through the shielding layer, will produce interference signals on each core wire. But the shielded cable applied to relay protection and automatic device circuit, as its input and output are at one end of the power grid high voltage or extra high pressure environment, electromagnetic interference is the main factor to prevent transient overvoltage, the cable shielding layer of the electric relay protection and automatic device should be grounded at both ends.