CN204375987U - The little resistance ground network of main equipment - Google Patents

Abstract

A small-resistance grounding network for large-scale equipment, including a horizontal grounding electrode and a vertical grounding electrode; the horizontal grounding electrode is arranged under the ground and arranged vertically and horizontally to form a horizontal grounding electrode plane network, and several vertical grounding electrodes are perpendicular to the horizontal grounding electrode plane network, It is arranged at several intersection points of the horizontal ground electrodes arranged vertically and horizontally, and is connected with the horizontal ground electrodes through arc-shaped clips. The lower part of the vertical grounding electrode is placed in a thin-walled iron casing, and the drag-reducing agent is poured in the thin-walled iron casing, and the wall of the thin-walled iron casing is provided with holes. The horizontal grounding electrode is set in the trench, and the bottom surface of the trench is provided with a support rod. The horizontal grounding electrode is fixed on the support rod and is located in the center of the cross section of the trench. The drag reducing agent is poured in the trench. The utility model reduces the construction cost, saves land, completes the small resistance grounding network in a small area, ensures the stability of the grounding effect, and ensures the safe and stable operation of the grounding equipment.

Description

Small resistance grounding grid for large equipment

technical field

The utility model belongs to the technical field of house construction electrical engineering and large-scale equipment grounding, and in particular relates to a small-resistance grounding network for large-scale equipment.

Background technique

The first phase project of Lanzhou Heavy Ion Medical Research Center and Testing and Commissioning Center of Institute of Modern Physics, Chinese Academy of Sciences is an industrial plant integrating R&D, production, commissioning and maintenance. The cost of a single magnet power supply is about 5 million. During commissioning, in order to avoid overvoltage , Overcurrent damages the equipment and suppresses the impact of overcurrent on equipment debugging. Based on calculations, the Institute of Near Physics, Chinese Academy of Sciences puts forward the requirement for a 0.2Ω resistance grounding grid. It is an independent grounding grid that is designed and constructed separately from the lightning protection grounding grid of the building, and belongs to the design and construction category of the small resistance grounding grid. The location of the magnetic grounding network is close to the Yellow River. On the one hand, the soil resistivity is low, but on the other hand, it increases the difficulty of construction. During the construction of the vertical grounding pole, the resistance reducing agent is easy to be lost with the movement of the quicksand layer, especially in the vertical grounding pole. Subsidence is prone to occur during construction, and it is found from the foundation survey report that within a certain depth there are construction waste and sand interbedded with stone backfill layers, making the soil resistivity reach 67Ω. About m, what is more difficult is that the construction unit proposed to use only 2000 square meters of green area as the land for the grounding grid. Through calculation, the product of the land area and the resistance of the grounding grid is 370, and generally this value has reached more than 700 , so there is no experience in China to learn from. Using such a small-area grounding grid to ensure the safety of equipment is a major technical problem we face.

Contents of the invention

The technical problem to be solved by the utility model is to provide a small-resistance grounding grid for large-scale equipment with simple construction, good use effect, low cost and small floor space.

The technical scheme adopted by the utility model to solve the above-mentioned technical problems is as follows: a small-resistance grounding network for large-scale equipment, including horizontal grounding electrodes and vertical grounding electrodes; Pole plane network, several vertical ground electrodes are perpendicular to the horizontal ground electrode plane network, set at several intersection points of the horizontal ground electrodes arranged vertically and horizontally, and connected with the horizontal ground electrode through arc clips, the horizontal ground electrode plane network is approximately in the center Set the lead-out pole of the ground grid.

The lower part of the vertical grounding electrode is placed in a thin-walled iron casing, and the drag-reducing agent is poured in the thin-walled iron casing, and the wall of the thin-walled iron casing is provided with holes.

The horizontal grounding electrode is set in the trench, and the bottom surface of the trench is provided with a support rod. The horizontal grounding electrode is fixed on the support rod and is located in the center of the cross section of the trench. The drag reducing agent is poured in the trench.

Compared with the prior art, the utility model innovatively proposes the use of the characteristics of the integrity of the earth, and avoids the disadvantages of unstable grounding resistance of the grounding grid caused by seasonal changes through deep burial of the grounding electrode, and uses the buried depth as much as possible Under the condition of reducing the amount of earthwork excavation.

The utility model determines the burial depth of the horizontal grounding electrode by measuring the resistivity of the soil, calculating the maximum conductive distance of the soil, and combining the maximum thickness of the frozen soil in the local area. The soil is compacted by the formwork so that the resistance reducing agent is closely combined with the soil. The utility model innovatively proposes a thin-walled iron sheet as the casing, which avoids the increase in the amount of the drag reducing agent caused by the loss of the quicksand; the drag reducing agent is poured in the way of reverse support so that the drag reducing agent is closely combined with the soil, increasing the The conductive distance of the soil increases the conductive interface, effectively improving the ion enrichment problem caused by the large resistivity difference between the soil and the drag reducer.

Utilizing the utility model, a 0.2Ω grounding grid is completed on a ground surface area of 2000 square meters, so that the grounding resistance does not change with the seasons, and the construction cost is reduced by using the casing. After calculation, compared with the previous large-area construction, it is smaller The construction method of the resistance grounding grid, the utility model saves more than 1400 square meters of land, saves more than 850,000 yuan in costs, and saves more than 50% of construction costs.

From the analysis of the technical problems encountered in this utility model, the small resistance grounding network is completed in a small area, and the simple deep-buried grounding electrode in the past cannot solve this problem. If special materials (such as buried copper blocks) are used, the cost is too high; Therefore, starting from the premise of using conventional materials, the utility modeler increases the vertical grounding electrode, connects the horizontal grounding electrode with arc clips, and embeds the conductive soil of the horizontal grounding electrode under the permafrost layer to ensure the stability of the grounding effect and ensure the grounding effect. The equipment runs safely and stably.

The utility model is a summary of practical engineering applications. It is applied to my country's first heavy ion cancer treatment equipment to ensure its debugging and put into use. There is no gap in the method of grounding grid design and construction in engineering construction. The utility model is suitable for the construction of modern large-scale equipment grounding grids with limited land area.

Description of drawings

Fig. 1 is a schematic diagram of the layout of soil resistivity test points when the utility model is applied,

Fig. 2 is a schematic plan view of the utility model grounding grid,

Figure 3 is a cross-sectional view of the horizontal ground electrode construction trench,

Fig. 4 is a schematic diagram of the structure of the arc clip,

Figure 5 is a schematic diagram of the structural relationship between the vertical ground electrode and the thin-walled iron casing and the pre-cast drag reducing agent,

Fig. 6 is a schematic diagram of connecting the horizontal ground electrode and the vertical ground electrode through arc clips.

In the figure: 1—horizontal grounding electrode, 2—vertical grounding electrode, 3—exiting pole of grounding grid, 4—arc clip, 5—thin-walled iron casing, 6—template, 7—hole, 8—resistance reducing agent, 9—soil resistivity test point, 10—support rod, 11—horizontal grounding grid, 12—groove, A—grid side length, B—horizontal grounding grid grid side length, C—arc clip Lap length with the horizontal ground electrode, e—the distance between the upper edge of the arc clip and the upper end of the vertical ground electrode.

Detailed ways

Embodiment, as shown in Figure 2 and Figure 6: a small-resistance grounding network for large-scale equipment, including a horizontal grounding electrode 1 and a vertical grounding electrode 2; the horizontal grounding electrode 1 is arranged under the ground, and the horizontal grounding electrode plane is formed according to the vertical and horizontal Grid 11, several vertical ground electrodes 2 are perpendicular to horizontal ground electrode plane grid 11, set at several intersection points of horizontal ground electrodes 1 arranged vertically and horizontally, and connected with horizontal ground electrode 1 through arc clip 4, horizontal ground electrode plane The grounding grid lead-out pole 3 is arranged at the approximate center of the grid 11 . The distance e between the upper edge of the arc clamp and the upper end of the vertical grounding pole is 20-30 mm.

See Figure 5: the lower part of the vertical grounding electrode 2 is placed in a thin-walled iron casing 5, and the drag-reducing agent 8 is poured in the thin-walled iron casing 5, and the wall of the thin-walled iron casing 5 is provided with holes 7; the vertical grounding electrode 2. It is made of Φ150mm galvanized steel pipe, and the resistance reducing agent 8 is poured in the galvanized steel pipe. The height of the thin-walled iron casing is higher than the normal water level of groundwater.

See Figure 3: The horizontal grounding electrode 1 is made of 60×8mm galvanized flat iron. The horizontal grounding electrode 1 is set in the groove 12, and the bottom surface of the groove 12 is provided with a support rod 10. The horizontal grounding electrode 1 is fixed on the support rod 10 and is located on the In the middle position of the cross section of the groove 12, the drag reducing agent is poured in the groove 12.

The horizontal ground electrode 1 is set 5m below the ground, and the vertical ground electrode 2 is set 10-15m below the ground.

See Figure 4: The arc clip 4 is made of 60×8mm galvanized flat iron. Since the position of the vertical ground electrode 2 on the horizontal ground electrode plane net 11 is different, the arc of the arc clip 4 is 90 or 180 degrees. The overlapping length C between the clip and the horizontal ground electrode is greater than 300mm.

The utility model is applied to rich water and high water level areas, and its design and construction method includes the following steps:

a. Determination of soil resistivity: As shown in Figure 1, under the condition that there is no rainfall and the weather is relatively dry within one week before the test, the grounding grid area is divided into grids with a grid side length A of 10×10 meters, and the grids are manually opened. After digging 1 meter deep, determine the soil resistivity test point 9 according to the four-wire method, use the ZC-8 grounding resistance tester to test the resistivity, and take the maximum value as the design soil resistivity.

b. Determination of the burial depth of the horizontal ground electrode and the depth of the vertical ground electrode: the maximum thickness of frozen soil in winter obtained through the query, plus the optimal conductive distance of the soil, determine the burial depth of the horizontal ground electrode, that is, the excavation depth; the vertical ground electrode The excavation depth is 2~3 times of the buried depth of the horizontal grounding pole.

c. Determination of grounding materials: In order to reduce the cost, 60×8mm galvanized flat iron is used for the horizontal grounding electrode and the arc clip, Φ150mm galvanized steel pipe is used for the vertical grounding electrode, and the copper iron with the same cross-section as the horizontal grounding electrode is used for the grounding grid lead-out pole The conversion part, the lead-out cable of the lead-out pole of the grounding grid adopts a single-core Φ240mm copper core flexible cable.

d. Line setting and earthwork excavation: According to the buried depth of the horizontal ground electrode determined in step c, the ground grid area is excavated as a whole, and the slope is set according to the slope of 1:1.5 to prevent collapse; as shown in Figure 2 and Figure 3, In the excavated grounding grid area, excavate the horizontal grounding electrode trenches 12 according to the grid whose side length B of the horizontal grounding grid grid is 6×6m; and release eight vertical grounding electrodes 2 evenly on the grid Location;

e. Vertical ground electrode construction: see Figure 5, determine the height of the thin-walled iron casing according to the normal water level higher than the groundwater, make the thin-walled iron casing 5 in advance, and open the hole 7 in the thin-walled iron casing 5; The tamping machine excavates the vertical ground electrode hole to the buried depth of the vertical ground electrode, which is 15 meters relative to the surface of the horizontal ground electrode; After the geometric center of the wall iron casing, pour the resistance reducing agent 8 into the thin wall iron casing and the galvanized steel pipe; the vertical grounding electrode 2 should be higher than the horizontal grounding electrode by more than 20cm, pour the resistance reducing agent 8 to the horizontal on the outside of the galvanized steel pipe At the level of grounding electrode 1, the inner side is filled with galvanized round steel.

f. Horizontal ground electrode construction: see Figure 6 and Figure 3, use the arc-shaped clamp to wrap the galvanized steel pipe as the vertical ground electrode to ensure a good connection, connect the two ends of the arc-shaped clamp with the galvanized flat iron as the horizontal ground electrode Welding, welding adopts lap welding, the lap length is greater than 300mm, and the welding place is anti-corrosion with iron red; at the same time, in the horizontal ground electrode trench 12 excavated in step d, use template 6 to support to form a width × height 30 × For a trench 12 of 30 cm, set a support rod 10 on the bottom of the trench, fix the horizontal grounding electrode 1 on the support rod and locate it in the center of the cross section of the trench, backfill and tamp the outside of the formwork with rural soil with low resistivity; remove the formwork , pouring the drag reducing agent in the trench.

g. Construction of ground lead-out wires: Use copper-iron conversion parts as the grounding grid lead-out pole 3, lead the grounding grid using copper-iron conversion parts, and weld the iron terminals of the pre-welded copper-iron conversion parts to the plated wire used as the horizontal grounding electrode. On the zinc flat iron, brush the iron red once; then weld the copper terminal to the flexible cable, and use three oil and two felts for anti-corrosion treatment on the copper and iron parts exposed outside the drag reducing agent.

h. Soil backfill: within 80cm of the surface of the horizontal ground electrode 1, manually backfill and tamp according to the thickness of each layer of 20cm, and the compactness is guaranteed to be above 0.93; the soil above 80cm is mechanically backfilled according to the thickness of 30±5cm, and the compactness is guaranteed to be Above 0.93; after the backfill is completed, measure the grounding resistance of the grounding grid again to confirm whether it meets the construction requirements.

Claims (5)

1. the little resistance ground network of main equipment, comprises horizontal grounding pole, vertical grounding electrode; It is characterized in that: horizontal grounding pole (1) being arranged at subsurface, forming horizontal grounding polar plane net (11) according to laying in length and breadth, several vertical grounding electrode (2) is perpendicular to horizontal grounding polar plane net (11), the several joint being arranged on the horizontal grounding pole (1) of laying in length and breadth being connected with horizontal grounding pole (1) by arc clamp (4), and horizontal grounding polar plane net (11) approximate centre position arranges ground network extraction pole (3).

2. the little resistance ground network of a kind of main equipment as claimed in claim 1, it is characterized in that: the bottom of vertical grounding electrode (2) is placed in thin-walled iron-sheet casing (5); built resistance reducing agent (8) in thin-walled iron-sheet casing (5) cylinder, and thin-walled iron-sheet casing (5) barrel is provided with hole (7).

3. the little resistance ground network of a kind of main equipment as claimed in claim 2, it is characterized in that: horizontal grounding pole (1) is arranged at groove (12), groove (12) bottom surface is provided with support bar (10), horizontal grounding pole (1) is fixed on support bar (10) and goes up and the middle position being positioned at groove (12) cross section, and groove has built resistance reducing agent in (12).

4. the little resistance ground network of a kind of main equipment as described in claim 1,2 or 3, is characterized in that: vertical grounding electrode (2) Φ 150mm coating steel pipe makes, and has built resistance reducing agent (8) in coating steel pipe.

5. the little resistance ground network of a kind of main equipment as claimed in claim 4, it is characterized in that: horizontal grounding pole (1) makes of the zinc-plated band iron of 60 × 8mm, arc clamp (4) the zinc-plated band iron of 60 × 8mm makes, the arc radian of arc clamp (4) is 90 or 180 degree, and arc clamp and the horizontal grounding pole lap of splice (C) are greater than 300mm; On arc clamp, edge is 20 ~ 30 millimeters with the distance (e) of vertical grounding electrode upper end.