ABB 3BHL000986P7001 数字输出继电器 模拟输出模块

ABB 3BHL000986P7001 数字输出继电器 模拟输出模块

ABB 3BHL000986P7001 数字输出继电器 模拟输出模块

PLC控制系统的地线包括系统地、屏蔽地、交流地和保护地等。接地系统混乱对PLC系统的干扰主要是各个接地点电位分布不均，不同接地点间存在

地电位差，引起地环路电流，影响系统正常工作。例如电缆屏蔽层必须一点接地，如果电缆屏蔽层两端A、B都接地，就存在地电位差，有电流流过

屏蔽层，当发生异常状态如雷击时，地线电流将大。

此外，屏蔽层、接地线和大地有可能构成闭合环路，在变化磁场的作用下，屏蔽层内有会出现感应电流，通过屏薇层与芯线之间的耦合，干扰信号回

路。

若系统地与其它接地处理混乱，所产生的地环流就可能在地线上产生不等电位分布，影响PLC内逻辑电路和模拟电路的正常工作。PLC工作的逻

辑电压干扰容限较低，逻辑地电位的分布干扰容易影向PLC的逻辑运算和数据存贮，造成数据混乱、程序跑飞或死机。模拟地电位的分布将导致测量

精度下降，引起对信号测控的严重失真和误动作。

主要由系统内部元器件及电路间的相互电磁辐射产生，如逻辑电路相互辐射及其对模拟电路的影响，模拟地与逻辑地的相互影响及元器件间的相互不

匹配使用等。这都属于PLC制造厂对系统内部进行电磁兼容设计的内容，比较复杂，作为应用部门是无法改变，可不多考虑，但要选择具有较多应用

实绩或经过考验的系统。

ABB 3BHL000986P7001 数字输出继电器 模拟输出模块

The ground wire of PLC control system includes system ground, shielding ground, alternating ground and protection ground. The disturbance of the grounding system to the PLC system is mainly due to the uneven distribution of potential at each ground point, which exists between different ground points

The ground potential difference causes the ground loop current and affects the normal operation of the system. For example, the cable shield layer must be grounded at one point. If A and B at both ends of the cable shield layer are grounded, there is a ground potential difference and a current flows through

Shielding layer. When an abnormal state occurs, such as a lightning strike, the grounding current is large.

In addition, the shielding layer, the ground wire and the earth may form a closed loop. Under the action of changing magnetic field, the induced current will appear in the shielding layer, which will interfere with the signal return through the coupling between the screen layer and the core wire

Road.

If the system is confused with other grounding, the resulting ground circulation may produce unequal potential distribution on the ground wire, affecting the normal operation of the logic circuit and analog circuit in the PLC. Logic of PLC operation

The voltage interference tolerance is low, and the distribution interference of the logic ground potential is easy to shadow the logic operation and data storage of PLC, resulting in data confusion, program flying or crash. The distribution of simulated ground potentials will lead to measurements

The decrease of accuracy causes serious distortion and misoperation of signal measurement and control.

It is mainly generated by the mutual electromagnetic radiation between the internal components and circuits of the system, such as the mutual radiation of the logic circuit and its influence on the analog circuit, the mutual influence of the analog and logic and the mutual difference between the components

Match use, etc. This belongs to the PLC manufacturer's electromagnetic compatibility design content inside the system, which is more complex, and can not be changed as an application department, but it is not considered much, but it is necessary to choose more applications

A proven or tested system.