HVC-02B ABB 分散控制系统 模块卡件

HP-5517B Agilent 传感器 激光干涉仪

Agilent HP 5517B来自接地系统混乱时的干扰：接地是提高电子设备电磁兼容性（EMC）的有效手段之一，正确的接地，既能抑制电磁干扰的影响，又能抑制设备向外发出干扰；而错误的接地，反而会引入严重的干扰信号，使DCS系统将无法正常工作。

DCS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DCS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，引起接地环路电流，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，则有电流流过屏蔽层，当发生异常状态如雷击时，地线电流将更大。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，Agilent HP 5517B 通过屏蔽层与芯线之间的耦合，干扰信号回路。若系统地与其他接地处理混乱，所产生的地环流就可能在地线上产生不等电位分布，影响DCS内逻辑电路和模拟电路的正常工作。DCS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响DCS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，Agilent HP 5517B 引起对信号测控的严重失真和误动作。来自DCS系统内部的干扰主要由系统内部元器件及电路间的相互电磁辐射产生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DCS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的，可不必过多考虑，Agilent HP 5517B 但要选择具有较多应用实绩或经过考验的系统。为了 系统在电力电磁环境中免受或减少内外电磁干扰，必须从设计阶段开始便采取三个方面抑制措施：抑制干扰源；切断或衰减电磁干扰的传播途径；提高装置和系统的抗干扰能力。这三点就是抑制电磁干扰的基本原则。

HP-5517B Agilent 传感器 激光干涉仪

Agilent HP 5517B Interference from the grounding system confusion: grounding is one of the effective means to improve the electromagnetic compatibility (EMC) of electronic equipment, the correct grounding, not only can inhibit the influence of electromagnetic interference, but also can inhibit the equipment to emit interference; The wrong grounding will introduce serious interference signals, so that the DCS system will not work normally.

The ground wire of DCS control system includes: system ground, shielded ground, alternating ground and protected ground. The disturbance of the grounding system to the DCS system is mainly the uneven distribution of potential at each ground point, and the ground potential difference between different ground points, which causes the grounding 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 the shield layer. When an abnormal state occurs, such as lightning strikes, the ground current will be larger. In addition, the shielding layer, the ground wire and the earth may form a closed loop, under the action of changing magnetic fields, there will be induced current in the shielding layer, Agilent HP 5517B through the coupling between the shielding layer and the core wire, interfering with the signal loop. 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 DCS. The logic voltage interference tolerance of DCS is low, and the distribution interference of the logic ground potential is easy to affect the logic operation and data storage of DCS, resulting in data confusion, program flying or crash.

The distribution of simulated ground potential will lead to the decrease of measurement accuracy, and Agilent HP 5517B will cause serious distortion and misoperation of signal measurement and control. The interference from the DCS system is mainly generated by the mutual electromagnetic radiation between the internal components and circuits of the system, 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 mismatch between the components. This belongs to the DCS manufacturer's internal electromagnetic compatibility design content of the system, more complex, as an application department is unable to change, you do not have to think too much, Agilent HP 5517B, but to choose a more application performance or tested system. In order to protect the system from or reduce internal and external electromagnetic interference in the electric electromagnetic environment, three suppression measures must be taken from the design stage: suppression of interference sources; Cut off or attenuate the transmission path of electromagnetic interference; Improve the anti-interference ability of devices and systems. These three points are the basic principles of suppressing electromagnetic interference.

HP-5517B Agilent 传感器 激光干涉仪