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1¡¢ Main function of solid state decoupler
The main function of solid-state decoupler is to protect the cathode of pipeline, reduce circuit failure and prolong its service life. This is because the cathodic protection system of the pipeline has some disadvantages, that is, more electromagnetic interference, or more stray current coupling. These stray currents cause great interference in daily use and affect the service life of the pipeline to a great extent. In this way, solid-state decoupler came into being, which can effectively eliminate the current that does not conform to the cathodic protection, reduce the probability of failure and the interference to communication, and can prevent the pipeline from being damaged by lightning, thunderstorm and other severe weather. In addition, solid-state decoupler can also reduce some adverse factors to human body.
2¡¢ Working principle of solid state decoupler
Solid state decoupler grounding is a method given in nacesp0177-2007, which is widely used in foreign projects to mitigate AC interference. Meanwhile, it has been successfully applied in domestic large-scale long-distance pipeline projects in recent years. Solid state decoupler has good anti lightning and fault current impulse performance, which is often used to protect pipelines, insulation devices and other fault current and lightning interference, but there are still some problems in practice.
At present, there is still a lack of corresponding inspection means and standards for solid-state decouplers, including clamp drain devices. At the same time, there is a lack of long-term tracking test and evaluation on the performance of related products, so it is impossible or impossible to judge the performance and quality of products. In case of failure, it is difficult to maintain in time. Therefore, the relevant standards for the detection and inspection of drainage equipment should be formulated and promulgated as soon as possible.
The position of discharge point largely determines the drainage effect. In practice, the preliminary study on the operating distance of solid-state decoupler shows that although a single solid-state decoupler can reduce the AC interference voltage near the discharge point, it can increase the AC interference voltage near the discharge point, and some pipe sections even increase greatly.
Therefore, in order to meet the requirements of AC mitigation, solid-state decoupler should be used in principle according to the field interference. It is suggested that step-by-step design and construction, supplemented by synchronous testing, should be adopted when the drainage is feasible, and the application position of the next drainage point should be determined according to the discharge.
3¡¢ Notes on installation of solid state decoupler
The requirement of solid-state decoupler discharging current to grounding material is relatively low, as long as the grounding resistance meets the relevant requirements, but foreign experience tells us that the fault of decoupler is short-circuit state, so the selection of grounding electrode material should be considered. However, it should be noted that the grounding electrode construction can not touch the tower, substation or communication tower of high-voltage transmission line, or the grounding body of large-scale buildings, because in case of lightning or high-voltage transmission failure, the fault current is easy to lead to the pipeline.
There are two installation methods for solid-state decoupler, namely surface mounting and bracket mounting. Among them, the surface installation is to connect one end of the solid-state decoupler to the pipeline, and the other end to the grounding grid. Here, we should pay attention to the resistance value of the grounding grid. In addition, the bracket installation is to install the solid-state decoupling device in the explosion-proof box structure, and the service life of the solid-state decoupling device under this installation mode will be longer than that of the surface installation.
Shandong Linyi Bosi conductive materials Co., Ltd. is a high-tech enterprise specializing in the production of MMO flexible anode, conductive polymer flexible anode and titanium coated anode, mainly providing corrosion protection, cathodic protection, engineering design, installation and technical services.