The grounding device is a fundamental piece of equipment for the normal operation of power equipment. It is a crucial measure for ensuring personal safety and the safety of electrical equipment. Without effective grounding protection, unforeseen safety accidents can occur. This is especially critical in the petrochemical industry, where the density of electrical equipment is high, and there are many flammable and explosive materials, making the lack of grounding protection even more hazardous. This article will introduce the advantages of using copper-clad steel plates as grounding materials.
The corrosion resistance of a grounding body directly determines the service life of the substation grounding grid. Steel itself has poor corrosion resistance, whilethe corrosion rate of copper grounding bodies in soil is about 1/101/10 to 1/50 that of steel. The corrosion product of copper is basic copper carbonate, which tightly adheres to the copper surface, blocking further corrosion and protecting the copper from pitting. When the coating is reasonable, the corrosion resistance of copper-clad steel plates is comparable to that of copper. The copper-clad steel grounding grid can operate stably for up to 50 years.
The conductivity of grounding grid materials directly affects the power frequency resistance and impact resistance of the substation grounding grid. According to the International Annealed Copper Standard (IACS), the conductivity of standard copper is 100% while that of standard steel is only 10.8%. The conductivity of copper-clad steel plates ranges from 20% to 40%, depending on the coating thickness, which is much better than that of steel grounding materials. During high-frequency lightning current impacts, the skin effect of conductors becomes more pronounced, further enhancing the high-frequency conductivity of copper-clad steel plates compared to steel grounding materials.
In substation grounding designs, copper-plated steel stranded wire is generally used as horizontal grounding grid material, and copper-plated round steel is used as vertical grounding electrodes. The length of galvanized flat steel is limited, resulting in many splice joints during the overall grid layout.However, the length of each roll of copper-plated steel stranded wire can reach 200m, significantly reducing the number of joints, minimizing construction work, and improving system reliability. As vertical grounding electrodes, copper-clad steel plates are easier to drive deep into the soil compared to galvanized angle steel, making the grounding construction more convenient.
Copper-clad steel plates not only have the electrical conductivity of copper but also inherit the strength and excellent elasticity of steel. This composite material exhibits high stability when subjected to mechanical stress, meeting the strength requirements for petrochemical equipment. Additionally, copper-clad steel plates have good plasticity, making them easy to process and form, providing convenience for equipment manufacturing and installation.
In summary, copper-clad steel plates, as a type of bimetallic composite material, utilize chemical or physical methods to uniformly attach copper to the treated carbon steel substrate, forming a dense cladding layer. Copper-clad steel plates combine the advantages of both copper and steel, significantly saving copper material, and are currently being used to some extent in the domestic power, petrochemical, and rail transit industries.
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