Grounding grid downlead corrosion test device

Abstract

The invention provides a grounding grid downlead corrosion test device, and relates to the technical field of power system safety. The device comprises a soil corrosion test box body with a closed bottom surface and closed side surfaces and without an upper surface, wherein a soil layer, a stone layer and an air layer are sequentially arranged in the soil corrosion test box body from shallow to deep; platinum sheet electrodes are arranged in the soil layer and the stone layer at equal depth intervals; a reference electrode is arranged at a preset depth position in the soil layer; the potential value of the platinum sheet electrode relative to the reference electrode is used for measuring the soil oxidation-reduction potential; a sample for a grounding grid downlead corrosion test is arranged in the soil corrosion test box body; one end of the sample is positioned on the bottom surface of the soil corrosion test box body, and the other end of the sample is positioned in the air layer. The device provided by the embodiment of the invention can be applied to grounding grid corrosion diagnosis and reason analysis.

Description

Technical Field

[0001] The invention relates to the technical field of power system safety, and in particular to a grounding grid down conductor corrosion test device. Background Art

[0002] The grounding device is an important part of the substation, converter station and transmission tower in the power industry. The status of its equipment is related to whether the power system can operate safely, stably and continuously. The grounding grid is the "safety valve" of the entire power system. It can discharge lightning current and short-circuit current to the earth in time to avoid voltage counterattack, which greatly endangers the electrical equipment and personal safety of the substation. Based on the importance of the grounding grid in the power system, the power grid company will conduct routine inspections on it, including checking that the grounding down conductor is connected normally, without loosening, displacement, anti-corrosion paint without shedding, breakage and severe corrosion; regularly conduct electrical integrity tests and grounding resistance tests on the grounding grid; the grounding grid of non-underground substations that have been in operation for 10 years or more is regularly excavated (at intervals of no more than 5 years) to check the anti-corrosion coating of the grounding body, coating defects, corrosion and breakage of the grounding material body, and the cross-sectional area of ​​the conductor. The corrosion diagnosis results can be obtained by measuring the port resistance between the grounding down conductors and performing numerical calculations based on the port resistance values.

[0003] The grounding down conductor is a key component of the grounding grid, which connects various electrical equipment in the atmosphere to the grounding grid in the soil so that the short-circuit current and lightning current in the electrical equipment can be discharged to the earth through the down conductor and the grounding grid. Through the inspection of the grounding devices of multiple substations in service, it was found that there were many grounding down conductor fractures. The fractures generally occurred at the bends of the down conductors. The macroscopic and microscopic morphology analysis of the ports showed that the fractures were brittle, the cracks were tree-like, and the main cracks were thick and wide. This is a typical stress corrosion fracture phenomenon. The stress corrosion of the grounding down conductor causes fractures, which will cause the relevant electrical equipment to lose effective grounding protection and bring safety hazards. In order to protect the safe operation of power transmission and transformation equipment, it is necessary to effectively prevent the occurrence of such corrosion.

[0004] The prior art realizes the corrosion monitoring of the grounding grid down conductor by regularly checking the running status of the grounding grid down conductor, but there are defects in that the real-time continuity of the monitoring is poor and the essential cause of the corrosion of the grounding grid down conductor cannot be determined. Summary of the invention

[0005] In view of the problems in the prior art, an embodiment of the present invention provides a grounding grid down conductor corrosion test device, which can at least partially solve the problems in the prior art.

[0006] On the one hand, the present invention provides a grounding grid down conductor corrosion test device, comprising:

[0007] A soil corrosion test box body with closed bottom and side surfaces and no upper surface, wherein a soil layer, a stone layer and an air layer are arranged in order from shallow to deep inside the soil corrosion test box body;

[0008] Platinum electrodes are arranged at equal depths in the soil layer and the stone layer;

[0009] A reference electrode is provided at a preset depth in the soil layer; the potential value of the platinum electrode relative to the reference electrode is used to measure the soil redox potential;

[0010] A sample for grounding grid down conductor corrosion test is arranged inside the soil corrosion test box body; one end of the sample is located at the bottom surface of the soil corrosion test box body, and the other end is located in the air layer.

[0011] The geometric dimensions of the soil corrosion test box body are 50 cm in width, 10 cm in thickness and 45 cm in depth; the thickness of the soil layer is 30 cm, the thickness of the stone layer is 10 cm, and the particle size of the stones in the stone layer is 2-4 cm.

[0012] Wherein, the reference electrode is arranged at a depth of 26 cm.

[0013] Wherein, the electrode lead of the platinum sheet electrode extends out from the opening at the corresponding position on the side of the soil corrosion test box body.

[0014] Wherein, the electrode lead is a platinum wire lead, and correspondingly, the platinum wire lead and the platinum sheet electrode are welded by spot welding.

[0015] The platinum wire lead is sealed and insulated with a thermoplastic plastic sleeve, and the welding points between the platinum wire lead and the platinum sheet electrode and the opening of the plastic sleeve are sealed with epoxy resin.

[0016] The electrode lead of the reference electrode extends from the soil corrosion test box body above the air layer through the soil layer and the stone layer.

[0017] Wherein, the reference electrode is a saturated copper sulfate reference electrode.

[0018] Wherein, the sample is a galvanized steel sample, the shape of the galvanized steel sample is a flat strip shape, and the galvanized steel sample is vertically arranged inside the soil corrosion test box body.

[0019] The present invention provides a test method using the grounding grid down conductor corrosion test device, comprising:

[0020] obtaining test materials, wherein the test materials include the sample, simulated precipitation, simulated rainfall, and soil filling the soil layer;

[0021] Spraying the simulated precipitation and the simulated rainfall onto the upper surface of the stone layer respectively;

[0022] After the test, the sample is taken out from the soil corrosion test box body, the sample is cleaned, and the thickness change of the cleaned sample compared with the sample before the test is calculated;

[0023] The corrosion rate of the sample is calculated according to the thickness change and the test period, and a first change curve of the soil redox potential changing with different depths and a second change curve of the sample corrosion rate changing with different depths are respectively drawn;

[0024] The grounding grid down conductor corrosion test analysis results are obtained according to the first change curve and the second change curve.

[0025] The grounding grid down conductor corrosion test device provided by the embodiment of the present invention comprises a soil corrosion test box body with closed bottom and side surfaces and no upper surface, wherein soil layers, stone layers and air layers are arranged in sequence from shallow to deep inside the soil corrosion test box body; platinum sheet electrodes are arranged at equal depths in the soil layer and the stone layer; a reference electrode is arranged at a preset depth in the soil layer; the potential value of the platinum sheet electrode relative to the reference electrode is used to measure the soil redox potential; a sample for the grounding grid down conductor corrosion test is arranged inside the soil corrosion test box body; One end of the sample is located on the bottom surface of the soil corrosion test box body, and the other end is located in the air layer. The sample can be used in the diagnosis and cause analysis of grounding grid corrosion, and provides a way to analyze the causes and mechanisms of failures such as corrosion thinning, corrosion crack growth, corrosion sensitivity, and corrosion fracture at the bends of the down conductors on the concrete foundation of electrical equipment in the atmosphere, the bends of the down conductors at the junction of the atmosphere and the soil, and the bends between the vertical and horizontal sections of the grounding down conductors in the soil. It enriches the means of evaluating the corrosion status of the grounding grid down conductors, ensures the efficient and continuous operation of the grounding grid, and ultimately safeguards the safe and stable operation of various electrical equipment in the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0027] Figure 1 It is a structural schematic diagram of a grounding grid down conductor corrosion test device provided by an embodiment of the present invention.

[0028] Figure 2 It is a schematic diagram of the change of redox potential in gravel layer and soil layer with depth provided by an embodiment of the present invention.

[0029] Figure 3 It is a schematic diagram of the change of redox potential at different depths over time provided by an embodiment of the present invention.

[0030] Figure 4 It is a schematic diagram illustrating the effect of water spraying on soil redox potential provided by an embodiment of the present invention.

[0031] Figure 5 It is a schematic diagram illustrating the effect of simulated rainfall on soil redox potential provided by an embodiment of the present invention.

[0032] Figure 6 It is a schematic diagram illustrating the corrosion rate of galvanized steel at different soil depths provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention more clear, the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention. It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other arbitrarily.

[0034] Figure 1 FIG. 1 is a schematic diagram of a structure of a grounding grid down conductor corrosion test device provided by an embodiment of the present invention. Figure 1 As shown, the grounding grid down conductor corrosion test device provided by the embodiment of the present invention includes:

[0035] A soil corrosion test box body 1 is provided with a closed bottom and side surfaces and no upper surface, wherein a soil layer 2, a stone layer 3 and an air layer 4 are arranged in order from shallow to deep inside the soil corrosion test box body 1;

[0036] Platinum sheet electrodes 5 are arranged at equal depths in the soil layer 2 and the stone layer 3;

[0037] A reference electrode 6 is provided at a preset depth in the soil layer 2; the potential value of the platinum electrode 5 relative to the reference electrode 6 is used to measure the soil redox potential;

[0038] A sample 7 for grounding grid down conductor corrosion test is arranged inside the soil corrosion test box body 1 ; one end of the sample 7 is located at the bottom surface of the soil corrosion test box body 1 , and the other end is located in the air layer 4 .

[0039] The geometric dimensions of the soil corrosion test box body 1 are 50 cm in width, 10 cm in thickness and 45 cm in depth; the thickness of the soil layer 2 is 30 cm, the thickness of the stone layer 3 is 10 cm, and the particle size of the stones in the stone layer 3 is 2-4 cm.

[0040] Furthermore, the reference electrode 6 is arranged at a depth of 26 cm.

[0041] Furthermore, the electrode lead of the platinum sheet electrode 5 extends out from the opening at the corresponding position on the side of the soil corrosion test box body 1 .

[0042] Furthermore, the electrode lead is a platinum wire lead, and accordingly, the platinum wire lead and the platinum sheet electrode 5 are welded by spot welding.

[0043] Furthermore, the platinum wire lead is sealed and insulated with a thermoplastic plastic sleeve, and the welding points between the platinum wire lead and the platinum sheet electrode 5 and the opening of the plastic sleeve are sealed with epoxy resin.

[0044] Furthermore, the electrode lead of the reference electrode 6 extends from the soil corrosion test box body 1 above the air layer 4 through the soil layer 2 and the stone layer 3 .

[0045] Furthermore, the reference electrode 6 is a saturated copper sulfate reference electrode.

[0046] Furthermore, the sample 7 is a galvanized steel sample, the shape of the galvanized steel sample is a flat strip shape, and the galvanized steel sample is vertically arranged inside the soil corrosion test box body 1.

[0047] In order to simulate the soil corrosion environment of the grounding down conductor, a soil corrosion test box was made. The test box is made of PVC plastic with geometric dimensions of 50cm wide, 10cm thick and 45cm deep. The soil layer in the box is 30cm thick, and the upper part of the soil layer is covered with gravel with a particle size of 2-4cm, and the thickness of the gravel layer is 10cm.

[0048] In order to study the reasons for the serious corrosion of the grounding down conductor near the surface, the soil redox potential was measured with the gravel layer and soil depth. The soil redox potential represents the redox ability of the soil. It is the electrode potential of the platinum electrode measured with the platinum electrode as the indicator electrode. For this purpose, platinum sheet electrodes were implanted at different depths in the soil test box. The electrode lead is a platinum wire, and the platinum wire lead and the platinum sheet electrode are spot welded. The platinum wire lead is sealed and insulated with a thermoplastic plastic sleeve. The welding points of the platinum wire lead and the platinum sheet electrode and the opening of the plastic sleeve are sealed with epoxy resin.

[0049] The reference electrode used for measuring soil redox potential is a saturated copper sulfate reference electrode. The reference electrode is buried at a depth of 26 cm in the soil. The soil redox potentials described below are all potential values ​​relative to the saturated copper sulfate reference electrode.

[0050] The soil redox potential value is measured using an electrochemical workstation. The electrode potential value of the platinum electrode can be measured at a fixed time every day, and the potential value is read every 30 seconds. The continuous measurement time is 400 seconds, and the average value of the measurement results corresponding to each soil depth within 400 seconds is used as the soil redox potential value P of the corresponding soil depth on that day.

[0051] The soil redox potential value P during the entire test period mean Calculated as follows:

[0052]

[0053] Where T is the test period in hours, P i is P corresponding to the i-th day, t i is the continuous measurement duration corresponding to the i-th day, and n is the number of test days corresponding to the test cycle.

[0054] The grounding grid down conductor corrosion test device provided by the embodiment of the present invention comprises a soil corrosion test box body with closed bottom and side surfaces and no upper surface, wherein soil layers, stone layers and air layers are arranged in sequence from shallow to deep inside the soil corrosion test box body; platinum sheet electrodes are arranged at equal depths in the soil layer and the stone layer; a reference electrode is arranged at a preset depth in the soil layer; the potential value of the platinum sheet electrode relative to the reference electrode is used to measure the soil redox potential; a sample for the grounding grid down conductor corrosion test is arranged inside the soil corrosion test box body; One end of the sample is located on the bottom surface of the soil corrosion test box body, and the other end is located in the air layer. The sample can be used in the diagnosis and cause analysis of grounding grid corrosion, and provides a way to analyze the causes and mechanisms of failures such as corrosion thinning, corrosion crack growth, corrosion sensitivity, and corrosion fracture at the bends of the down conductors on the concrete foundation of electrical equipment in the atmosphere, the bends of the down conductors at the junction of the atmosphere and the soil, and the bends between the vertical and horizontal sections of the grounding down conductors in the soil. It enriches the means of evaluating the corrosion status of the grounding grid down conductors, ensures the efficient and continuous operation of the grounding grid, and ultimately safeguards the safe and stable operation of various electrical equipment in the power system.

[0055] The embodiment of the present invention provides a test method using the above-mentioned grounding grid down conductor corrosion test device, comprising:

[0056] obtaining test materials, wherein the test materials include the sample, simulated precipitation, simulated rainfall, and soil filling the soil layer;

[0057] Spraying the simulated precipitation and the simulated rainfall onto the upper surface of the stone layer respectively;

[0058] After the test, the sample is taken out from the soil corrosion test box body, the sample is cleaned, and the thickness change of the cleaned sample compared with the sample before the test is calculated;

[0059] The corrosion rate of the sample is calculated according to the thickness change and the test period, and a first change curve of the soil redox potential changing with different depths and a second change curve of the sample corrosion rate changing with different depths are respectively drawn;

[0060] The grounding grid down conductor corrosion test analysis results are obtained according to the first change curve and the second change curve.

[0061] The simulated precipitation was deionized water, and the simulated rainfall was an aqueous solution of sulfuric acid and nitric acid in a molar ratio of 9:1, with a pH of 5-6.

[0062] Spray water or simulate rainfall: use a spray bottle to spray 100mL of deionized water or simulated rainwater on the surface of the gravel layer. The rainfall intensity is about 2.6mm per hour.

[0063] The soil used in the experiment is sandy loam. The physical and chemical indicators of the soil are shown in Table 1:

[0064] Table 1

[0065]

[0066]

[0067] After the test, use a hard rubber shovel to remove the soil and rust and other corrosion products attached to the surface of the sample, use a brush dipped in deionized water to scrub the surface of the sample, and then use a cleaning solution to clean the corrosion products on the surface. The cleaning solution and cleaning conditions are shown in Table 2:

[0068] Table 2

[0069]

[0070] Due to the large size of the sample, it is inconvenient to measure the mass of the sample. Therefore, the method of measuring the sample thickness is adopted to measure the change Δh of the sample thickness h before and after corrosion, and then the corrosion rate of the sample is calculated according to the following formula:

[0071]

[0072] Where V is the corrosion rate of the sample, in mm / a; h0 is the thickness of the sample before corrosion (the thickness of the sample before the test), h1 is the thickness of the sample after corrosion (the thickness of the sample after the test); Δh = h0-h1, which is the difference in thickness before and after corrosion (the thickness change); h0, h1 and Δh are all in mm. T is the test period, in hours (h); 8760 is the number of hours in a year.

[0073] The thickness of the sample is measured with a vernier caliper accurate to 0.01 mm.

[0074] like Figure 2 As shown in the figure, in the gravel layer, the redox potential increases with depth and reaches the maximum at the interface between the gravel layer and the soil layer. In the soil layer, the change of redox potential with soil depth is more complex, with peaks and troughs appearing at intervals. The troughs appear at 22cm and 28cm, and the peaks appear at 24cm and 33cm.

[0075] like Figure 3 As shown in the figure, at a soil depth of 20 cm, on April 25, just after the experiment began, the redox potential here was higher than that of its neighboring areas. From April 26 to April 30, the potential here was lower than that of its neighboring areas and was at a trough. After that, the trough at 20 cm moved to 22 cm. At 28 cm, except for the first two days after the experiment began, that is, April 25 and April 26, the potential value here was always at a trough, lower than the potential value of its neighboring areas.

[0076] like Figure 4 As shown in Figure 2, after spraying deionized water onto the surface of the stone layer, the redox potential values ​​at various locations generally showed an upward trend. Figure 3 It can be seen that after spraying water, the potential at a depth of 28 cm increased significantly, and the potential value trough here disappeared.

[0077] like Figure 5 As shown in the figure, after spraying simulated rainwater, the potential values ​​at various depths in the soil layer showed an overall significant upward trend, but the potential values ​​at various locations in the gravel layer did not increase significantly. The potential value at a depth of 28 cm increased significantly, and the potential trough here disappeared. The potential value at a depth of 22 cm changed from decrease to increase to decrease with time, while the potential at 20 cm changed very little with time, so that the trough of the potential value moved back and forth between 20 cm and 22 cm.

[0078] like Figure 6 As shown, for both sample 1 and sample 2, the corrosion rate is the highest near the interface between the gravel layer and the soil layer.

[0079] In the gravel layer, except for the surface of the gravel layer (8 cm), the corrosion rate of galvanized steel increases with the depth of the gravel layer, and the corrosion rate reaches the maximum at the junction of the gravel layer and the soil layer. Figure 2 The results shown in the figure show that the redox potential increases with depth in the gravel layer. Therefore, it can be considered that the corrosion rate of galvanized steel increases with the increase of redox potential in the gravel layer.

[0080] In the soil layer, as the soil depth increases, the change in the corrosion rate of galvanized steel is more complex, showing multiple peaks and troughs, but the overall trend is that the corrosion rate decreases with increasing soil depth. At 28cm, the corrosion rates of samples 1 and 2 are faster, showing a peak of corrosion rate; this peak of corrosion rate corresponds to Figure 2 The trough of soil redox potential is shown in Figure 2. At 20cm and 22cm, the corrosion rates of both sample 1 and sample 2 are at a relatively large value. Figure 2 corresponds to the trough of the redox potential. On the other hand, Figure 2 At 24cm and 33cm of the peak of redox potential, the corrosion rates of both sample 1 and sample 2 are at lower values. Therefore, it can be considered that the corrosion rate is lower at the peak of soil redox potential, but the corrosion rate is higher at the adjacent location with low redox potential.

[0081] The redox potential of a medium represents the redox ability of the medium. Generally, galvanized steel corrodes faster in a medium with a higher redox potential.

[0082] As mentioned above, in the gravel layer, the corrosion rate of galvanized steel increases with the increase of redox potential. On the other hand, in the soil layer, the corrosion rate is low at the location of the soil redox potential peak, but the corrosion rate is high at the location of the low redox potential near the redox potential peak. This indicates that the corrosion mechanism of galvanized steel in the gravel layer and in the soil layer may be different.

[0083] In the corrosion of grounding down conductors, it is generally believed that due to the low oxygen concentration deep in the soil and the high oxygen concentration in the soil surface, an oxygen differential charging cell is formed. The electrode potential is high at the location of the high oxygen concentration in the soil surface, and it becomes the cathode of the differential charging cell. Deep in the soil, the oxygen concentration is low and the electrode potential is low, and it becomes the anode of the differential charging cell and is corroded. Therefore, the most severely corroded part of the grounding down conductor is usually located about 5 cm below the ground. Since only the redox potential of the soil was measured in this experiment, the electrode potential of the sample at different soil depths was not measured, and the differential charging cell mechanism of the above-mentioned grounding down conductor corrosion has not been directly confirmed.

[0084] In this experiment, a gravel layer was laid on the soil layer. At the interface between the gravel layer and the soil layer, the redox potential and the corrosion rate were the highest, which is consistent with the common belief that galvanized steel corrodes faster in media with higher redox potentials.

[0085] In the soil layer, as mentioned above, the corrosion rate is low at the location of the soil redox potential peak, but the corrosion rate is high at the location of the redox potential near the redox potential peak. This is inconsistent with the aforementioned understanding that "galvanized steel corrodes faster in a medium with a higher redox potential". However, if the electrode potential of the sample is high at the location of the soil redox potential, then, since the electrode potential of the sample at the location of the high redox potential and the location of the low redox potential are different, a macroscopic corrosion cell is formed, and the electrode potential of the sample at the location of the low redox potential is also low. It will corrode at a faster rate as an anode in the corrosion cell. In places where the soil redox potential is high, the electrode potential of the sample is high, and the sample will corrode more slowly as a cathode in the corrosion cell. This explanation is consistent with the results obtained in the experiment.

[0086] The results of this test analysis show that:

[0087] 1) In the gravel layer, except for the surface of the gravel layer, as the depth of the gravel layer increases, the redox potential increases, and the corrosion rate of galvanized steel increases; 2) At the interface between the gravel layer and the soil layer, the redox potential is the highest, and the corrosion rate of galvanized steel is the fastest; 3) In the soil layer, as the soil depth increases, the soil electrode potential shows a phenomenon of alternating peaks and troughs. The corrosion rate is low at the location of the soil redox potential peak, but the corrosion rate is high at the location of the redox potential near the redox potential peak; 4) Water spraying or simulated rainfall has no obvious effect on the trend of the redox potential changing with depth in the gravel layer, but it has an effect on the redox potential trough in the soil layer, but the redox potential trough disappears at a greater depth.

[0088] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0089] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0090] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0091] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0092] In the description of this specification, the description with reference to the terms "one embodiment", "a specific embodiment", "some embodiments", "for example", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0093] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A grounding grid down conductor corrosion test device, characterized in that: include: A soil corrosion test box body with closed bottom and side surfaces and no upper surface, wherein a soil layer, a stone layer and an air layer are arranged in order from shallow to deep inside the soil corrosion test box body; Platinum electrodes are arranged at equal depths in the soil layer and the stone layer; A reference electrode is provided at a preset depth in the soil layer; the potential value of the platinum electrode relative to the reference electrode is used to measure the soil redox potential; A sample for grounding grid down conductor corrosion test is arranged inside the soil corrosion test box body; one end of the sample is located at the bottom surface of the soil corrosion test box body, and the other end is located in the air layer.

2. The grounding grid down conductor corrosion test device according to claim 1, characterized in that: The geometric dimensions of the soil corrosion test box body are 50 cm in width, 10 cm in thickness and 45 cm in depth; the thickness of the soil layer is 30 cm, the thickness of the stone layer is 10 cm, and the particle size of the stones in the stone layer is 2-4 cm.

3. The grounding grid down conductor corrosion test device according to claim 2, characterized in that: The reference electrode was set at a depth of 26 cm.

4. The grounding grid down conductor corrosion test device according to claim 1, characterized in that: The electrode lead of the platinum sheet electrode extends out from the opening at the corresponding position on the side of the soil corrosion test box body.

5. The grounding grid down conductor corrosion test device according to claim 4, characterized in that: The electrode lead is a platinum wire lead, and accordingly, the platinum wire lead is welded to the platinum sheet electrode by spot welding.

6. The grounding grid down conductor corrosion test device according to claim 5, characterized in that: The platinum wire lead is sealed and insulated with a thermoplastic plastic sleeve, and the welding points of the platinum wire lead and the platinum sheet electrode and the opening of the plastic sleeve are sealed with epoxy resin.

7. The grounding grid down conductor corrosion test device according to claim 1, characterized in that: The electrode lead of the reference electrode extends from the soil corrosion test box body above the air layer through the soil layer and the stone layer.

8. The grounding grid down conductor corrosion test device according to claim 7, characterized in that: The reference electrode is a saturated copper sulfate reference electrode.

9. The grounding grid down conductor corrosion test device according to claim 1, characterized in that: The sample is a galvanized steel sample, which is in the shape of a flat strip and is vertically arranged inside the soil corrosion test box body.

10. A test method using the grounding grid down conductor corrosion test device as claimed in claim 1, characterized in that: include: obtaining test materials, wherein the test materials include the sample, simulated precipitation, simulated rainfall, and soil filling the soil layer; Spraying the simulated precipitation and the simulated rainfall onto the upper surface of the stone layer respectively; After the test, the sample is taken out from the soil corrosion test box body, the sample is cleaned, and the thickness change of the cleaned sample compared with the sample before the test is calculated; The corrosion rate of the sample is calculated according to the thickness change and the test period, and a first change curve of the soil redox potential changing with different depths and a second change curve of the sample corrosion rate changing with different depths are respectively drawn; The grounding grid down conductor corrosion test analysis results are obtained according to the first change curve and the second change curve.

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