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Grounded concept
The earth soil we live in has the characteristics of low resistance, large capacitance, absorbing infinite charge and no potential change. Using this feature, it can be used as a reference potential body in electricity, and its potential is artificially defined as zero potential. Also known as electrical "ground".
Grounding is to connect a certain part of the power system or electrical installation and building facilities to the grounding body through a grounding connection wire. A long-term low-impedance grounding system is an important guarantee to ensure the stable operation of modern electrical facilities. It not only ensures personnel and equipment, but also the economy of investment and operation.
Types of commonly used grounding materials
| Galvanized Copper In a few countries in the world represented by galvanized copper materials in China, India and the former Soviet Union, steel is used as the main grounding material in traditional engineering applications. The one-time investment of the project is low in cost, easy to purchase, and low in construction cost, but the material has poor corrosion resistance and short service life. |
| Pure copper (red copper) In most countries in the world and the projects under construction in my country, pure copper is used as the grounding material, which has the characteristics of good electrical conductivity and high corrosion resistance. However, the cost of such projects is large at one time, and the economic performance is not advantageous. |
| Non-metallic grounding module This type of product uses carbon-based graphite of various shapes formed at high temperature and high pressure as the main material to fix steel connectors inside. The electrical conductivity is lower than that of various metals, graphite has low mechanical strength, is fragile, inconvenient for storage, transportation, installation and maintenance, and graphite is prone to burst under the impact of transient high current; steel connectors have poor corrosion resistance and short service life; above Both factors can cause the overall failure of the grounding system. |
| Composite grounding products (ionic grounding) This type of product was invented and applied abroad, and has been introduced into China in the past ten years. The product uses hollow copper as the grounding body, the middle is filled with water-soluble and decomposable compounds, and the outside is filled with compound fillers that can relieve the release of electrolytic ions. At the same time, the external compound filler can effectively block the corrosion of various organic salts, acids, alkaline substances and microbial organic compounds in the soil to the metal grounding body. Such products are expensive and are only suitable for vertical grounding in harsh soil environments. |
| Copper clad steel products (copper plated steel, continuous casting copper clad steel) These products combine the high electrical conductivity and corrosion resistance of copper with the high mechanical strength and low cost of steel to achieve complementary advantages. At present, copper-coated steel products have formed a mature certification and specification system such as UL, CE, and IEEE in the world. There is no international standard for continuous casting copper-clad steel products. |
Design standards and specifications for grounding systems
Domestic standard
○ GB 50169-2006 "Electrical installation engineering-grounding installation construction and acceptance specification"
○ GB 14050-2008 "Types and technical requirements for system grounding"
○ GB 50057-2010 "Code for Lightning Protection Design of Buildings"
○ GB 50343-2012 "Technical Specification for Lightning Protection of Electronic Information System of Buildings"
○ GB 50065-2011 "Code for Grounding Design of AC Electrical Installations"
○ GB /T 21698-2008 "Technical Conditions for Composite Grounding Body"
○ GB 16895.3-2004 "Electrical Installations in Buildings Part 5-54 Selection and Installation of Electrical Equipment Grounding Configuration, Protective Conductor and Protective Bonding Conductor"
○ GB /T 17949.1-2000 "Guidelines for Measuring Soil Resistivity, Grounding Impedance and Ground Co-potential of Grounding Systems Beginning: Routine Measurements"
○ GB 16895.9-2000-T "Electrical installations in buildings-Part 7: Requirements for special installations or locations Section 707: Grounding requirements for backup electrical installations for data processing equipment"
○ GB 16895.17-2000-T "Electrical installations in buildings - Part 5: Selection and installation of electrical equipment - Section 548 Grounding equipment and equipotential bonding of information technology installations"
○ GJBZ 25-91 "Guidelines for Grounding, Bonding and Shielding Design of Electronic Equipment and Facilities"
○ DL/T 1312-2013 "Technical Conditions for Copper Clad Steel for Grounding of Power Engineering"
○ DL/T 1312-2013 "Technical Conditions for Slow-release Ion Grounding Devices for Power Engineering"
○ DL/T 1315-2013 "Technical Conditions for Exothermic Flux for Grounding Devices in Power Engineering"
○ DL/T 1342-2014 "Materials and Connectors for Electrical Grounding Engineering"
○ DL 475-2006 "Guidelines for the measurement of characteristic parameters of grounding devices"
○ DL/T 5091-1999 "Technical Guidelines for Grounding Design of Hydropower Plants"
○ QX/T 104-2009 "Grounding Resistance Reducer"
○ YD/T 1429-2006 "Technical requirements and testing methods for lightning protection systems in use by communications bureaus (stations)"
○ SH 3097-2000 "Petrochemical Electrostatic Grounding Design Specification"
○ Q/GDW 466-2010 "Technical Conditions for Copper Clad Steel for Grounding in Electrical Engineering"
○ Q/GDW 467-2010 "Technical Guidelines for Exothermic Welding of Grounding Devices"
Comparison of common grounding materials
Contrast content | Conventional galvanized steel | Copper material | Graphite grounding module | Liangou series copper-plated steel |
Production process | Hot dip galvanizing | Copper | Peripheral die casting of metal core layer | Four-dimensional continuous electroplating |
Service life | 3-10 years | Over 100 years | 3-10 years | Over 100 years |
Grounding stability | Unstable | Stable | Unstable | Stable |
Thermal stability | General | Good | Difference | Good |
Mechanical strength | Good | General | Poor | Good |
Construction face | Very large | Larger | Very large | Smaller |
Price comparison | Low one-time investment | Expensive | Slightly higher than the price of traditional steel grounding | Slightly higher than the price of traditional steel grounding |
Easy to maintain | Perennial maintenance, easy to corrode | Maintenance-free | The metal core is easy to corrode, and the cross-sectional area of the inner steel core is small, which can not meet the requirements of mechanical properties and thermal effects under lightning strikes | Maintenance-free |
Electrical conductivity | 8.6% based on the conductivity of pure copper | Conductivity | Lower than all kinds of commonly used metal conductors | High frequency current conduction is equivalent to pure copper |
Welding process | Conventional welding | Gas welding or exothermic welding | Conventional welding | Exothermic welding |
Technical standard | National standard | National standard | Non-standard | UL, CE, IEEE, Electric Power Standard |
