Protection device against AC interference

In order to prevent possible AC interference to buried metal structures, reduce possible hazardous structures, and avoid related operations of electrical hazards, some effective protection devices and measures can be adopted, such as DC grounding body decoupling device can be installed in direct and latent structures.

Generally speaking, electrical shielding usually uses shell, mesh or other objects as shielding material and the structure affected on one side of installation, so as to fully reduce the influence of electric field on the back of electrical equipment or line to protect the affected structure. Electrical shielding is often used to protect buried structures from the impact of AC power system to ground arc, so as to reduce the possibility of corrosion protection layer and even structure itself being damaged under impact.

Grounding pad is a bare conductor system installed on the ground or underground, also known as gradient control board. These bare conductors are usually composed of metal plates or grids arranged and connected to each other to provide an equipotential across the span.

The so-called grounding grid refers to some exposed conductors buried in the ground connected with each other to form a grounding electrode system to provide common grounding. No matter what kind of material is used to make the grounding pad, it must be connected to the structure, preferably in multiple positions at the same time. If the cathodic protection of the structure is difficult to operate normally due to grounding, DC decoupling device can be installed.

Independent structure grounding refers to the installation of any metal structure which is not connected with the existing grounding structure. The grounding system can be composed of all or more grounding electrodes and their wiring. All parts of the earthing structure shall be properly connected.

The bridge of the existing structure is an effective way to reduce the induced AC voltage of the structure. The affected structure is connected to the grounding device of the power system by using cables with appropriate cross-sectional area and DC decoupling device. In the event of a fault, the voltage and current of the affected structure will increase significantly during the fault due to the jumper connection. If the affected structure is on the ground or well insulated from the ground, significant high potential will be generated and propagated along the length of the bridge structure.

Distributed anode is a protective measure that uses sacrificial anode as a part of grounding system to reduce AC potential between structure and ground. When the distributed anode is used, the sacrificial anode should be installed near the protection structure and away from the power grounding system. It is better to connect the anode directly to the structure without test connection in the middle, which can reduce the number of contact points in the connection system, provide the shortest path to the ground, and reduce the contact opportunity between personnel and structure.

The bushing can be used to reduce the resistance of the structure to the ground under surge conditions. It is used to connect bare steel casing or poorly coated casing with anticorrosive coating structure. By careful DC decoupling device, this not only resists the ground structure in surge, but also avoids the arc between structure and casing.

Insulated joint is used in cathodic protection project to realize electrical insulation between protected structure or protected section and unprotected section to ensure that cathodic protection current is limited in protected section.

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 cathodic protection technology, engineering design, installation and technical services. Tel: 0539 3712117, 15588026668.

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