Method for testing characterization parameters of high-conductivity fiber grounding material

Abstract

The invention relates to a method for testing characterization parameters of a high-conductivity fiber grounding material, which comprises the following steps: an anode is a working electrode and is a self-discharging electrode of high-conductivity fiber grounding material concrete coated with a carbon steel test piece; an auxiliary electrode of the cathode is a processed and molded copper electrode; two groups of tests are set, one group is an additive-free concrete control group, and the other group of concrete shell materials are prepared according to the proportion of the high-conductivity fiber grounding material and the foundation concrete; respectively welding a lead with the two electrodes by using an electric soldering iron, and respectively connecting with the positive electrode and the negative electrode of a direct-current source; after the electrodes are manufactured and connected, immersing the electrodes into an electrolytic bath and electrifying and electrolyzing at room temperature; taking out the carbon steel test piece after specified days, cleaning the surface by a water bath method, testing and recording a result; calculating metal corrosion degree, power frequency grounding resistance and impact resistance parameters according to a formula; the device has the advantages of adopting an orthogonal experiment, power frequency grounding resistance measurement and impact grounding resistance measurement.

Description

Technical Field

[0001] The invention belongs to the technical field of power transmission line grounding, and in particular relates to a method for testing characterization parameters of a high-conductivity fiber grounding material. Background Art

[0002] The grounding grid is an important part of the power system. First of all, it provides a common reference ground for various electrical equipment. More importantly, it plays a role in quickly discharging fault current when a ground fault occurs in the system, improving the distribution of ground potential between the metal conductor of the ground grid and the surface of the field, and ensuring the safety of primary and secondary equipment and personnel under fault conditions. Ordinary concrete is neither an insulator nor a good conductor. Its resistivity varies greatly. It is about 107~109Ω·cm in a dry state, while the resistivity of completely wet concrete can be reduced to 10~103Ω·cm. The new high-conductivity fiber grounding material is a new type of concrete. Its basic principle is to add a conductive phase (such as conductive particles or conductive fibers) to ordinary concrete. After adding the conductive phase, its resistivity can be greatly reduced. There have been many studies on conductive concrete grounding materials with different adding options. In China, some areas have used graphite materials as grounding materials. It is used in actual lightning protection and grounding projects. However, with the increase in power grid operating power, the construction of ultra-high voltage transmission lines and the continuous improvement of lightning resistance requirements, the discharge capacity of tower grounding devices needs to be improved urgently; soil resistivity plays an important role in the grounding design of transmission line towers. Grounding resistance is an important indicator to measure the grounding effect of transmission line towers and an important standard for whether the grounding device meets the current regulations. Grounding resistance will be affected to a large extent by soil resistivity. Therefore, parameter measurement of new high-conductivity fiber grounding materials is of great significance to improving the lightning protection level and safe and stable operation of transmission lines with higher resistivity. However, there is currently a lack of relevant research on parameter measurement of new high-conductivity fiber grounding materials at home and abroad; therefore, it is very necessary to provide a high-conductivity fiber grounding material characterization parameter test method using orthogonal experiments, power frequency grounding resistance measurement, and impact grounding resistance measurement. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a method for testing the characterization parameters of high-conductivity fiber grounding materials using orthogonal experiments, power frequency grounding resistance measurements, and impact grounding resistance measurements.

[0004] The object of the present invention is achieved by providing a method for testing characterization parameters of a high-conductivity fiber grounding material, the method comprising the following steps:

[0005] Step 1: Make the anode: The anode is the working electrode, which is a self-contained electrode made of high-conductivity fiber grounding material concrete wrapped around a carbon steel test piece;

[0006] Step 2: Make the cathode: The auxiliary electrode of the cathode is a processed copper electrode;

[0007] Step 3: Two groups were set up for the experiment. One group was a control group with concrete without additives, and the other group's concrete shell material was made according to the ratio of high-conductivity fiber grounding material and foundation concrete in Step 1;

[0008] Step 4: Apply voltage: Use a soldering iron to solder the wires to the two electrodes, and then connect them to the positive and negative poles of the DC source respectively;

[0009] Step 5: Electrolysis: After the electrodes are made and connected, they are immersed in the electrolytic tank and electrolyzed at room temperature;

[0010] Step 6: After the specified number of days, remove the carbon steel test piece, clean the surface in a water bath, test, and record the results;

[0011] Step 7: Calculate the metal corrosion degree, power frequency grounding resistance and impulse resistance parameters according to the formula.

[0012] The external voltage in step 4 is a direct current source with an external voltage of 1V.

[0013] The electrolysis temperature in step 5 is 20°C to 30°C.

[0014] The electrolyte in step 5 was respectively configured to be 3.5%, 4.5%, 5.5% and 6.5% NaCl solutions for electrolysis test.

[0015] The step 6 specifically includes: taking out the carbon steel test piece after the specified number of days, taking a 20% hydrochloric acid organic corrosion inhibitor solution, cleaning the surface in a 40-50° C. water bath, and testing and recording the results.

[0016] The metal corrosion degree parameter in step 7 is calculated using the weight loss method, specifically: Where: V is the corrosion rate; M0 is the mass of the specimen before corrosion; M1 is the mass of the specimen after corrosion; t is the experimental time; S is the surface area of ​​the specimen; A is the average corrosion depth of the specimen surface; δ is the specimen density.

[0017] The calculation of the power frequency grounding resistance parameters in step 7 is specifically as follows: According to the definition of resistance and capacitance, the differential form of Gauss's theorem and Ohm's theorem, we have: R = U / I (3), C = Q / U (4), ∮ S Dds=∮ S εEds=Q(5), Where: R is the power frequency grounding resistance of the grounding device; C is the capacitance of the grounding device; ε is the dielectric constant; ρ is the resistivity. The calculation of the impulse resistance parameters is as follows: For the impulse resistance, one of the important parameters - the impulse coefficient a, is: Where: β and m are the shape factors of the grounding device; I is the impulse current amplitude; ρ is the soil resistivity; l is the length of the grounding device.

[0018] The high conductivity fiber grounding material in step 1 is a multiphase composite material formed by mixing and condensing a gelling material, a conductive material, 0.5% to 1% of metal fiber, a dielectric aggregate, an ionic material and water according to a certain proportion.

[0019] The conductive material is graphite; the metal fiber is steel fiber; and the gelling material is cement and fly ash.

[0020] The concrete shell material of another group in step 3 is made of high-conductivity fiber grounding material with reference to the additive and admixture formula determined by orthogonal test and the base concrete mix ratio.

[0021] Beneficial effects of the present invention: The present invention is a method for testing the characterization parameters of high-conductivity fiber grounding materials. The high-conductivity fiber grounding materials of the present invention have good electrical conductivity and ductility, and their strength is higher than that of general composite materials. Therefore, the present invention can not only be applied to the selection of grounding materials, but also has the characteristics of other conductors such as electrothermal, pressure-sensitive, temperature-sensitive, and electromagnetic shielding. This makes the present invention gradually applied to various special projects such as de-icing and snow melting, building thermal insulation, electromagnetic shielding, and damage detection, which has great long-term value and great future prospects. In use, the present invention is the first to use graphite, metal fiber and a third-phase additive to make a high-conductivity fiber grounding material, and then provide the grounding material with relevant frequency grounding resistance and impact grounding resistance. The test method of characterization parameters such as resistance can reduce the accident rate of transmission lines under large current impact, significantly improve the safety and reliability of transmission lines, significantly improve the service life of grounding materials, reduce power outage time during the entire service cycle, and reduce operation and maintenance costs; the high conductivity fiber grounding material of the present invention effectively solves the problem that the resistivity, compressive and flexural strength and corrosion resistance cannot be taken into account after adding a conductive phase to the power transportation grounding body, and this competitive relationship limits the further improvement of the current-carrying capacity of the grounding device. The present invention realizes low resistance, high conductivity, high strength, pollution-free and corrosion-resistant properties at the same time, ensuring the safe and stable operation of the power transportation system; the present invention has the advantages of adopting orthogonal experiments, power frequency grounding resistance measurement, and impact grounding resistance measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the electrochemical corrosion test diagram of the present invention.

[0023] Figure 2 This is a schematic diagram showing the principle of using the four-electrode method of the present invention to measure concrete resistivity. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the accompanying drawings.

[0025] Example 1

[0026] like Figure 1-2 As shown, a method for testing the characterization parameters of a high-conductivity fiber grounding material comprises the following steps:

[0027] Step 1: Make the anode: The anode is the working electrode, which is a self-contained electrode made of high-conductivity fiber grounding material concrete wrapped around a carbon steel test piece;

[0028] Step 2: Make the cathode: The auxiliary electrode of the cathode is a processed copper electrode;

[0029] Step 3: Two groups were set up for the experiment. One group was a control group with concrete without additives, and the other group's concrete shell material was made according to the ratio of high-conductivity fiber grounding material and foundation concrete in Step 1;

[0030] Step 4: Apply voltage: Use a soldering iron to solder the wires to the two electrodes, and then connect them to the positive and negative poles of the DC source respectively;

[0031] In this embodiment, the external voltage is a direct current source with an external voltage of 1V to accelerate the corrosion process.

[0032] Step 5: Electrolysis: After the electrodes are made and connected, they are immersed in the electrolytic tank and electrolyzed at room temperature;

[0033] In this embodiment, the electrolysis temperature is 20° C. to 30° C.; the electrolyte is respectively configured to be 3.5%, 4.5%, 5.5%, and 6.5% by mass of NaCl solution for electrolysis test.

[0034] Step 6: Two groups were set up for the experiment. One group was a control group with concrete without additives, and the other group’s concrete shell material was made according to the additive and admixture formula and base concrete mix ratio determined by the orthogonal test;

[0035] Step 7: After the specified number of days, remove the carbon steel test piece, clean the surface in a water bath, test, and record the results;

[0036] In this embodiment, specifically, the carbon steel test piece is taken out after the specified number of days, 20% hydrochloric acid organic corrosion inhibitor solution is taken, the surface is cleaned by water bath method at 40-50°C, and the test results are recorded.

[0037] Step 7: The most important criteria for measuring the effectiveness of the grounding device are the power frequency grounding resistance and the impulse grounding resistance. Calculate the metal corrosion degree, power frequency grounding resistance and impulse resistance parameters according to the formula.

[0038] In this embodiment, ① the metal corrosion degree parameter is calculated using the weight loss method, specifically: Where: V is the corrosion rate (g / (m 2 h); M0 is the mass of the specimen before corrosion (g); M1 is the mass of the specimen after corrosion (g); t is the experimental time (d); S is the surface area of ​​the specimen (cm 2 ); A is the average corrosion depth of the specimen surface (mm / a); δ is the density of the specimen (g / cm 3 ).

[0039] ② Calculation of power frequency grounding resistance parameters: According to the definition of resistance and capacitance, the differential form of Gauss's theorem and Ohm's theorem, we have: R = U / I (3), C = Q / U (4), ∮ S Dds=∮ S εEds=Q(5), Where: R is the power frequency grounding resistance of the grounding device (Ω); C is the capacitance of the grounding device (F); ε is the dielectric constant (F / m); ρ is the resistivity (Ω·m);

[0040] ③Calculation of impulse resistance parameters: Specifically, for impulse resistance, one of the important parameters, the impulse coefficient a, is: Where β and m are the shape factors of the grounding device; I is the impulse current amplitude (KA); ρ is the soil resistivity (Ω·m); and l is the length of the grounding device (m).

[0041] The present invention is a method for testing the characterization parameters of high-conductivity fiber grounding materials. The high-conductivity fiber grounding materials of the present invention have good electrical conductivity and ductility, and their strength is higher than that of general composite materials. Therefore, the present invention can not only be applied to the selection of grounding materials, but also have the characteristics of other conductors such as electric heating, pressure sensitivity, temperature sensitivity, and electromagnetic shielding. This makes the present invention gradually applied to various special projects such as de-icing and snow melting, building thermal insulation, electromagnetic shielding, and damage detection, and has great long-term value and great future prospects. In use, the present invention is the first to use graphite, metal fiber and a third phase additive to make a high-conductivity fiber grounding material, and then provide the grounding material with relevant frequency grounding resistance and impact grounding resistance and other characterization parameters. The invention provides a quantitative testing method, which reduces the accident rate of transmission lines under large current impact, significantly improves the safety and reliability of transmission lines, significantly improves the service life of grounding materials, reduces power outage time during the entire service cycle, and reduces operation and maintenance costs; the high conductivity fiber grounding material of the invention effectively solves the problem that the resistivity, compressive and flexural strength and corrosion resistance cannot be taken into account after adding a conductive phase to the power transportation grounding body, and this competitive relationship limits the further improvement of the current-carrying capacity of the grounding device; the invention realizes low resistance, high conductivity, high strength, pollution-free and corrosion-resistant performance at the same time, and ensures the safe and stable operation of the power transportation system; the invention has the advantages of adopting orthogonal experiments, power frequency grounding resistance measurement, and impact grounding resistance measurement.

[0042] Example 2

[0043] like Figure 1-2 As shown, a method for testing the characterization parameters of a high-conductivity fiber grounding material comprises the following steps:

[0044] Step 1: Make the anode: The anode is the working electrode, which is a self-contained electrode made of high-conductivity fiber grounding material concrete wrapped around a carbon steel test piece;

[0045] In this embodiment, the high-conductivity fiber grounding material is a multiphase composite material formed by mixing and solidifying a cementitious material, a conductive material, 0.5% to 1% metal fiber, a dielectric aggregate, an ionic material, and water according to a certain mix ratio, and has a concrete with certain conductive and mechanical properties. When the ratio of the high-conductivity fiber grounding material to concrete is 1:4, the corresponding performance reaches the optimal level.

[0046] The conductive material is graphite; the metal fiber is steel fiber; and the gelling material is cement and fly ash.

[0047] ① Steel fiber has the property of blocking the expansion of cracks in concrete, especially when 0.5% to 1% of steel fiber is added, the flexural tensile strength and shear strength of concrete are significantly improved, and its fatigue resistance, impact resistance, post-crack toughness and durability are greatly improved; however, the metallic steel fiber will produce an oxidized passivation layer on the surface in the alkaline environment of cement, which will lead to an increase in the overall resistivity of the concrete and a decrease in its conductive performance. Therefore, a comprehensive analysis of the conductivity and strength effects of steel fiber is conducted, and steel fiber is compounded with graphite concrete. On the basis of meeting the conductive performance, the strength requirements of concrete can also be guaranteed; steel fiber has the advantage of improving the tensile, flexural and flexural mechanical properties of concrete, and at the same time, as a metal, it can also play a conductive role.

[0048] ② Ionic materials are inorganic salts generated by ionic combination. After decomposition, they can produce a large number of ions and other conductive electrolytes. They have certain conductivity and have no corrosive effect on steel bars.

[0049] ③ The cementitious material is mainly composed of cement, which bonds other solid materials into a whole and mainly plays a solidifying role.

[0050] ④ Four-electrode method: The principle is to use four probes to connect with four electrodes in the concrete. The two probes in the middle measure the voltage value, and the two probes on both sides measure the current value. The resistivity is still obtained according to Ohm's law, such as Figure 2 As shown, therefore, in the design and calculation of the grounding device, the soil resistivity should be measured. The resistivity of the new high-conductivity fiber grounding material is measured using the four-level method. After the electrode for measuring resistance is set, the corresponding result can be calculated according to the corresponding formula; according to the "Standard", the grounding resistance of the transmission line tower should not exceed the specified data when the lightning rod is untied, whether in dry or wet conditions. The soil resistivity and grounding resistance are shown in the following table.

[0051]

[0052] ⑤ Environmental protection characteristics of high-conductivity fiber grounding materials: All materials in the high-conductivity fiber grounding materials of the present invention do not contain substances harmful to the environment. Due to the solidification characteristics of concrete itself, they will not be lost in the soil over time. They not only have no corrosive effect on the grounding body but also have a protective effect. They can stably reduce resistance for a long time and also reduce the cost of later use and maintenance. It is an ideal green and environmentally friendly resistance reduction material.

[0053] Preliminary tests show that high-conductivity fiber grounding materials have excellent electrical conductivity and corrosion resistance, and show significant excellence in compressive and flexural strength. The good performance of high-conductivity fiber grounding materials greatly reduces the maintenance costs of grounding projects and significantly improves their economic benefits in grounding projects.

[0054] Step 2: Make the cathode: The auxiliary electrode of the cathode is a processed copper electrode;

[0055] Step 3: Two groups were set up for the experiment. One group was a control group with concrete without additives, and the other group's concrete shell material was made according to the ratio of high-conductivity fiber grounding material and foundation concrete in Step 1;

[0056] In this embodiment, another group of concrete shell materials is made of high-conductivity fiber grounding materials with reference to the additive and admixture formulas and base concrete mix ratios determined by orthogonal experiments; the idea of ​​orthogonal experiments is used to analyze the resistance characteristics, stability characteristics, and corrosion resistance characteristics of conductive concrete under different ratios of the new high-conductivity fiber grounding materials, explore the influencing mechanism of different physical property change laws under different ratios, and then explore the optimal ratio of graphite, metal fiber, and cementitious material in the new high-conductivity fiber grounding materials, while ensuring that it is harmless to the environment.

[0057] Step 4: Apply voltage: Use a soldering iron to solder the wires to the two electrodes, and then connect them to the positive and negative poles of the DC source respectively;

[0058] Step 5: Electrolysis: After the electrodes are made and connected, they are immersed in the electrolytic tank and electrolyzed at room temperature;

[0059] Step 6: After the specified number of days, remove the carbon steel test piece, clean the surface in a water bath, test, and record the results;

[0060] Step 7: Calculate the metal corrosion degree, power frequency grounding resistance and impulse resistance parameters according to the formula.

[0061] In this embodiment, the grounding material mainly relies on the electronic conductive mechanism to make the electron chains in close contact with each other, and has excellent conductive performance; electronic conductivity does not rely on water molecules to dissolve ions, so its conductive mechanism makes it less susceptible to external environmental influences and can ensure good long-term effectiveness; at the same time, it is not affected by changes in dryness, wetness, and coldness, and also has the characteristics of conductive stability; the grounding material has low resistivity, and adding it to concrete to become a concrete grounding body can effectively reduce the grounding resistance of the concrete foundation. Moreover, the grounding material itself is non-corrosive and can effectively protect the steel bars in the concrete foundation from electrochemical corrosion; according to the method in the "Compilation of Standards for Metal Corrosion Test Methods", an electrochemical corrosion test is designed, and the schematic diagram is shown as follows. Figure 1 shown.

[0062] There are three main types of electrical conduction in concrete: ionic, electronic, and hole conduction. Ionic conduction is generated by the movement of anions and cations such as Mg, Na, K, O, and Cl in the pores of concrete; electronic conduction is generated by the movement of free electrons in concrete; and hole conduction is generated by the movement of holes. Therefore, the overall conductivity K of concrete can be expressed as: K = K1 + K2 + K3 (9), where: K is the overall conductivity of concrete; K1 is the ionic conductivity; K2 is the electronic conductivity; and K3 is the hole conductivity.

[0063] The proportion of these three conductive forms in the overall conductive mode of concrete will change with the formula and proportion of concrete. When a small amount of conductive material is added, the main conductive forms in concrete are ionic conduction and hole conduction; when a large amount of conductive material is added, the main conductive forms in concrete are electronic conduction and hole conduction.

[0064] Corrosive ions: The corrosive ions that have a destructive effect on reinforced concrete structures are mainly Cl - and SO4 2- Generally, there are two ways for it to enter the concrete: one is through the addition of raw materials such as early strength agents and quick-setting agents, or the use of raw materials during production is not standardized, and aggregates containing sea salt are mixed in; the other is after the concrete is made and formed, it seeps into it through the external environment during the maintenance or use stage.

[0065] Impact of acidic gases: The destructive effect of acidic gases on steel bars is that they cause carbonization of concrete, that is, concrete with poor density is easily corroded by air. Acidic gases such as CO2 can react with Ca(OH)2 formed by cement hydration to produce carbonates, destroying the original high alkaline environment and turning it into weak alkaline or even acidic, while also destroying the passivation film on the surface of the steel bars. The specific process is as follows: CO2+H2O→H2CO3, H2CO3+Ca(OH)2→CaCO3+2H2O(11).

[0066] The influence of oxygen and water: From the mechanism of oxygen absorption corrosion, it can be seen that the necessary conditions for corrosion to occur are the participation of water and oxygen. The water in the concrete participates in the formation of pore solution. After dissolving certain salts, it forms the electrolyte solution of the primary battery, providing a working circuit for it. At the same time, water and oxygen together with the anode reactant F2 + The reaction produces rust. The sparse structure of rust is not only more conducive to the invasion of oxygen and moisture, but also because of its volume expansion, it will squeeze the external concrete and easily cause cracks in the outer layer of concrete. The specific process of rust generation is as follows: Fe2+2OH -→2Fe(OH)2(12), 4Fe(OH)2+O2+2H2O→4Fe(OH)3(13), 2Fe(OH)3→2H2O+Fe2O3·H2O(14).

[0067] Comparative conclusions of the test reports of benchmark concrete and new high-conductivity fiber grounding material for concrete. The test reports are based on: GB / T50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" and GB / T50082--2009 "Test Report on Long-term Performance and Durability of Ordinary Concrete" with reference to JC475-2004 "Concrete Antifreeze". It can be seen from the data of the standard comparative test that: in compressive strength, frost resistance test, and water penetration resistance test, the tested specimens are superior to the benchmark specimens; the conclusion that the new high-conductivity fiber grounding material has no corrosion effect on steel bars lays the foundation for the natural grounding device of the tower concrete, and at the same time solves the problem of easy corrosion of the grounding device; the new technology of the new high-conductivity fiber grounding material can make the grounding resistance stable in the long term, once and for all, ensuring the synchronization of economic development and environmental protection. The main technical indicators are shown in the following table.

[0068]

[0069] ① The new high conductivity fiber grounding material should be added to the concrete and used below the ground level. The new high conductivity fiber grounding material is added to the concrete and has excellent protection for ordinary non-galvanized or copper-plated round steel, and has an accelerated corrosion effect on galvanized and copper-plated metals.

[0070] The grounding down conductor should be connected to the foundation steel cage with ordinary non-galvanized or copper-plated round steel, and the exposed part should be treated with anti-rust paint; if galvanized or copper-plated round steel is used as the down conductor, ordinary welding can be used, with one end welded to the steel cage and the other end welded to the grounding down conductor, and anti-corrosion measures should be taken after welding.

[0071] If superconducting fiber grounding material is prepared at a commercial concrete mixing station, the volume should be calculated and the high-conductivity fiber grounding material should be evenly mixed with the gravel in proportion to ensure uniform mixing. If it is produced on site, the materials can be added simultaneously according to the mix ratio and poured after uniform mixing. When the grounding lead is led down the tower leg, a bow-shaped bend should be reserved to facilitate the operation unit to measure the grounding resistance. The amount of grounding material used in tower concrete and the grounding resistance of the natural grounding device are calculated: when the ratio of new high-conductivity fiber grounding material: concrete = 1:4, when the equivalent diameter of the main column of the tower concrete foundation is 1 meter, the amount of grounding material used and the power frequency grounding resistance are calculated according to the following formula: R = 0.25ρ / 2πL, where: R represents the power frequency grounding resistance value of a single tower concrete foundation (Q); ρ represents the soil resistivity corrected by the seasonal coefficient (Ω.m); L represents the burial depth of a single concrete foundation (m); the reference usage of the new high-conductivity fiber grounding material is shown in the following table.

[0072] Soil resistivity (Ω·m) Power frequency grounding resistance (Ω) Amount of new high-conductivity fiber grounding materials used (tons) 100<ρ<500 15 0.5 500<ρ<1000 20 1 1000<ρ<1500 25 1.5 1200<ρ<2000 25 2 2000<ρ<2500 30 2.5 2500<ρ<3000 30 3

[0073] ② Construction instructions for the natural grounding device of the new high-conductivity fiber grounding material: The new high-conductivity fiber grounding material used in concrete must be poured below the horizontal line. The new high-conductivity fiber grounding material used in concrete is only suitable for ordinary low-carbon steel as the metal grounding electrode. Copper-plated galvanized metal materials are strictly prohibited. When ordinary low-carbon steel grounding down conductor is used, the exposed soil part should be treated with anti-corrosion. When copper-plated galvanized metal materials are used as down conductors, U-shaped ordinary low-carbon round steel should be used, one end of which is connected to the steel cage and the other end is connected to the galvanized copper down conductor. The connection part is welded. Some parts should comply with the requirements of standards and specifications, and anti-corrosion measures should be taken at the same time; when calculating the power frequency grounding resistance, a 1:4 ratio is adopted to ensure the accuracy of the power frequency grounding resistance and the amount of new high conductivity fiber grounding material used; it can be flexibly controlled during construction, and according to actual conditions, it can be poured as a whole or partially, and the contradiction between the amount of new high conductivity fiber grounding material and the concrete volume can be correctly resolved to ensure an intact path for the new high conductivity fiber grounding material to contact the soil. The design volume of the concrete foundation should include the new high conductivity fiber grounding material.

[0074] ③Packaging, transportation and storage: This product is a black-grey solid powder, packed in bags, 25kg per bag; keep it away from moisture and rain, and do not store it with corrosive substances; this product is pollution-free and non-corrosive, and can be transported by train, car, ship, etc.

[0075] ④Verify the performance indicators of the new high-conductivity fiber grounding material in practice, and describe the results through photos or data; conduct grounding resistance testing on the dried concrete grounding material, and a total of three pieces are tested. The grounding resistance test results are shown in the following table.

[0076]

[0077] Through the test, we can see that the new high conductivity fiber grounding material is made into 0.125m 3 , the grounding resistance is reduced to 8.62Ω, and the new high conductivity fiber grounding material is made into 0.5m 3 , the grounding resistance dropped to 6Ω; three groups of concrete were connected together with steel bars for testing, and three groups of data were measured, which were 2.77, 2.77, and 2.76 respectively, with an average value of 2.77Ω; theoretically, if the soil resistivity is constant, the grounding resistance value will be reduced by half if the grounding grid area is doubled; it can also be concluded from this experiment: as the volume of the new high-conductivity fiber grounding material increases, the grounding resistance will further decrease, which is in line with the above law.

[0078] The present invention is a method for testing the characterization parameters of high-conductivity fiber grounding materials. The high-conductivity fiber grounding materials of the present invention have good electrical conductivity and ductility, and their strength is higher than that of general composite materials. Therefore, the present invention can not only be applied to the selection of grounding materials, but also have the characteristics of other conductors such as electric heating, pressure sensitivity, temperature sensitivity, and electromagnetic shielding. This makes the present invention gradually applied to various special projects such as de-icing and snow melting, building thermal insulation, electromagnetic shielding, and damage detection, and has great long-term value and great future prospects. In use, the present invention is the first to use graphite, metal fiber and a third phase additive to make a high-conductivity fiber grounding material, and then provide the grounding material with relevant frequency grounding resistance and impact grounding resistance and other characterization parameters. The invention provides a quantitative testing method, which reduces the accident rate of transmission lines under large current impact, significantly improves the safety and reliability of transmission lines, significantly improves the service life of grounding materials, reduces power outage time during the entire service cycle, and reduces operation and maintenance costs; the high conductivity fiber grounding material of the invention effectively solves the problem that the resistivity, compressive and flexural strength and corrosion resistance cannot be taken into account after adding a conductive phase to the power transportation grounding body, and this competitive relationship limits the further improvement of the current-carrying capacity of the grounding device; the invention realizes low resistance, high conductivity, high strength, pollution-free and corrosion-resistant performance at the same time, and ensures the safe and stable operation of the power transportation system; the invention has the advantages of adopting orthogonal experiments, power frequency grounding resistance measurement, and impact grounding resistance measurement.

Claims

1. A method for testing the characterization parameters of high-conductivity fiber grounding materials, characterized by: The method comprises the following steps: Step 1: Make the anode: The anode is the working electrode, which is a self-contained electrode made of high-conductivity fiber grounding material concrete wrapped around a carbon steel test piece; Step 2: Make the cathode: The auxiliary electrode of the cathode is a processed copper electrode; Step 3: Two groups were set up for the experiment. One group was a control group with concrete without additives, and the other group's concrete shell material was made according to the ratio of high-conductivity fiber grounding material and foundation concrete in Step 1; Step 4: Apply voltage: Use a soldering iron to solder the wires to the two electrodes, and then connect them to the positive and negative poles of the DC source respectively; Step 5: Electrolysis: After the electrodes are made and connected, they are immersed in the electrolytic tank and electrolyzed at room temperature; Step 6: After the specified number of days, remove the carbon steel test piece, clean the surface in a water bath, test, and record the results; Step 7: Calculate the metal corrosion degree, power frequency grounding resistance and impulse resistance parameters according to the formula.

2. A method for testing characterization parameters of a high-conductivity fiber grounding material according to claim 1, characterized in that: The external voltage in step 4 is a direct current source with an external voltage of 1V.

3. The method for testing the characterization parameters of a high-conductivity fiber grounding material according to claim 1, wherein: The electrolysis temperature in step 5 is 20°C to 30°C.

4. A method for testing characterization parameters of a high-conductivity fiber grounding material according to claim 3, characterized in that: The electrolyte in step 5 was respectively configured to be 3.5%, 4.5%, 5.5% and 6.5% NaCl solutions for electrolysis test.

5. The method for testing the characterization parameters of a high-conductivity fiber grounding material according to claim 1, wherein: The step 6 specifically includes: taking out the carbon steel test piece after the specified number of days, taking a 20% hydrochloric acid organic corrosion inhibitor solution, cleaning the surface in a 40-50° C. water bath, and testing and recording the results.

6. The method for testing the characterization parameters of a high-conductivity fiber grounding material according to claim 1, wherein: The metal corrosion degree parameter in step 7 is calculated using the weight loss method, specifically: Where: V is the corrosion rate; M0 is the mass of the specimen before corrosion; M1 is the mass of the specimen after corrosion; t is the experimental time; S is the surface area of ​​the specimen; A is the average corrosion depth of the specimen surface; δ is the specimen density.

7. A method for testing characterization parameters of a high-conductivity fiber grounding material according to claim 6, characterized in that: The calculation of the power frequency grounding resistance parameters in step 7 is specifically as follows: According to the definition of resistance and capacitance, the differential form of Gauss's theorem and Ohm's theorem, we have: R = U / I (3), C = Q / U (4), Where: R is the power frequency grounding resistance of the grounding device; C is the capacitance of the grounding device; ε is the dielectric constant; ρ is the resistivity. The calculation of the impulse resistance parameters is as follows: For the impulse resistance, one of the important parameters - the impulse coefficient a, is: Where: β and m are the shape factors of the grounding device; I is the impulse current amplitude; ρ is the soil resistivity; l is the length of the grounding device.

8. The method for testing the characterization parameters of a high-conductivity fiber grounding material according to claim 1, wherein: The high conductivity fiber grounding material in step 1 is a multiphase composite material formed by mixing and condensing a gelling material, a conductive material, 0.5% to 1% of metal fiber, a dielectric aggregate, an ionic material and water according to a certain proportion.

9. A method for testing characterization parameters of a high-conductivity fiber grounding material according to claim 8, characterized in that: The conductive material is graphite; the metal fiber is steel fiber; and the gelling material is cement and fly ash.

10. A method for testing characterization parameters of a high-conductivity fiber grounding material according to claim 1 or 8, characterized in that: The concrete shell material of another group in step 3 is made of high-conductivity fiber grounding material with reference to the additive and admixture formula determined by orthogonal test and the base concrete mix ratio.

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