With the development of our country's industry, the requirements for the automation level of industrial control systems are constantly increasing. In order to meet the requirements of automation control, DCS systems have been widely used in industrial automation control. Therefore, the reliability of DCS control system directly affects the safety production and economic operation of industrial enterprises. The anti-jamming ability of the system is the key to the reliable operation of the entire system. At present, the various control systems used in the automation system are mostly in the harsh electromagnetic environment formed by strong electric circuits and strong electrical equipment. In the construction site, when signals are transmitted between electrical equipment, instruments, DCS control systems, and DCS systems, there are often disturbances that cause system instability or even misoperation, and must be taken seriously. - What are the main introduction of interference - Resistance coupling interference In the course of work, many factories have neglected the problem of aging wires. When a variety of signal lines carry out signal transmission together, they may affect other transmission signals due to the aging of the insulating material on the wires, and interfere with other transmission signals. In addition to this, aging of the signal line will not only affect other signal lines, but some high-power circuits (eg, heat-generating circuits) will also cause significant interference to the signal if the line ages during use. Capacitive and inductive coupling interference Normally, the control cabinet on the site was connected to a number of signal lines. Some of these signal lines use cable ducts, some use cable ducts, especially when multiple signals are being routed at the same time, and there is a capacitance distribution between the signals. Signal lines interfere. In particular, an alternating magnetic flux is formed around the alternating signal line, which in turn creates a potential between the parallel conductors, causing potential interference signals. Lightning disturbance When a lightning strike occurs, large electromagnetic interference may be formed around the desired signal. Of course, the introduction of the interference path will also be caused by a variety of grounding lines. There are two main types of lightning interference: one is an overhead power line, which causes interference to the signal line due to a lightning strike; the other is a lightning strike around the signal cable, which results in the formation of capacitive, inductive coupling distribution on the signal line, and thus forms a large interference. Serious damage to equipment and personal injury. Power line interference As the large-scale equipment in the power plant starts and closes more frequently, the switching operations of large components are also frequent. When these large-scale motor equipments are switched, instantaneous large-scale alternating magnetic fields are generated. Alternating magnetic fields will couple on the signal line, which will cause interference to the system. These alternating magnetic fields will also generate high-frequency interference on the power line. If the signal level exceeds the specified range, it will also affect the system. In order to ensure the protection of the system when the large motor is switched, a transformer may be added to the circuit to ensure that the alternating magnetic field is not generated when the motor is switched and the voltage is too large. - The main cause of interference - Material and equipment issues The control signals that are connected to the DCS system usually use cables as the transmission medium to send signals to the DCS system. When the signal cable insulation material is aged and the shield material is damaged, it will be interfered by other electromagnetic interference sources. The interference will cause measurement errors and serious interference. Can cause equipment damage. The construction is not standardized In the DCS control system, there are often many signals that access the DCS at the same time. These signal lines either run through cable ducts or run through cable ducts, causing many different types of cables to be installed on the same path. There is a distributed capacitance between these signals, which will add interference to other signal lines through these distributed capacitors. At the same time, alternating magnetic fluxes are generated in the surrounding environment of the transmitted signal, such as power lines, motors, generators, power transformers, and relays. These magnetic fields often cause large disturbances. Unreasonable grounding The more common grounding accident is that both ends of the signal line are grounded, which will cause greater interference due to ground potential difference. If both ends of the signal line are grounded at the same time, there may be a large potential difference, and this potential difference may generate a large circulation on the signal line between the two ends. Generate electromagnetic waves, interference signals. There is also DCS system total grounding resistance does not meet the DCS system's normal operating requirements and so on. - How to suppress interference - Guarantee the normal use of signal lines During the use of the signal line, multiple signal lines are prevented from being entangled. At the same time, the signal line is regularly checked to repair and replace the signal line with damaged insulating colloid to ensure the normal use of the signal line and avoid leakage. It interferes with the transmission signal. Lay the cable The cables that transmit different signals are isolated and the cable is controlled in a layered manner to ensure that the cables do not interact with each other. For the cable that transmits the same signal, it is also necessary to avoid intensive entanglement of the line as much as possible. Because the computer port can perform a certain degree of precise analysis on the signal during processing, if there is a signal similar to each other when similar signals interfere with each other , It will affect the judgment of the computer, resulting in analysis errors during the computer's work. Signal line isolation During the operation of the equipment, the signals can be isolated by using cable isolation to ensure that the signals do not have mutual influence. However, the isolation method can not only isolate the transmission signal line, but also classify the signal isolation at the computer end. Using this isolation method can greatly reduce the harm caused by common mode interference to the computer. An isolation amplifier can also be used to completely isolate the input of the signal from the computer. In this way, a loop can be formed between the blocking of the interfering signals to suppress the harm of interference and ensure the normal operation of the system. Power supply system isolation Since some high-power motors are frequently switched on site, high-frequency signals are generated during the switching process. To prevent high-frequency electromagnetic interference to the system, a transformer can be installed on the power supply line, which can generate high-power motor switches. Frequency electromagnetic constraints to avoid impact on the system. Twist and shield The twisting of the signal wire, that is, twisted pair instead of parallel wire, can achieve the effect of suppressing the magnetic field interference. The shield is to use metal conductors to isolate components, assemblies and signal lines. Shielding can well suppress capacitive coupling noise. The common method is to connect analog signals through shielded twisted pairs. In general, not only electrical noise interferes with the signal, but strong alternating magnetic fields also interfere with the signal. Therefore, it is necessary not only to consider the electric shielding, but also to consider the magnetic shielding, and it is possible to adopt a conductor with excellent magnetic permeability (such as iron, nickel, etc.) to achieve shielding measures. Ground well For the DCS grounding system, it mainly includes two aspects: On the one hand, when the signal or power supply enters the DCS system or fails on its own, it can take over current and transfer it to the ground; on the other hand, the grounding system Shields can be provided to DCS, which in turn can block electronic noise interference, while providing a reference zero potential to all systems. So DCS systems usually include work and protection of 2 grounds. The Anti-explosion Screen Protector is a Screen Protector that can effectively buffer impact, prevent the screen from bursting, or prevent the glass panel from breaking and falling apart due to accidental impact of the mobile phone. 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