CN103457044B - The earthing device of 10kV distribution network overhead line tower pole and laying method thereof - Google Patents
The earthing device of 10kV distribution network overhead line tower pole and laying method thereof Download PDFInfo
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- CN103457044B CN103457044B CN201310320808.3A CN201310320808A CN103457044B CN 103457044 B CN103457044 B CN 103457044B CN 201310320808 A CN201310320808 A CN 201310320808A CN 103457044 B CN103457044 B CN 103457044B
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Abstract
A kind of earthing device of 10kV distribution network overhead line tower pole, the down conductor comprising electric equipment and the metallic ground body group imbedded in ground, imbed metallic ground body group in ground to be made up of the iron ring earthing body being embedded in underground around shaft tower, level and at least 3 bar-shaped earth electrodes being vertically embedded in underground, be overlapped on ring earthing body after described earth electrode upper end bending, down conductor lower end is connected electrically on ring earthing body, upper end then connects shaft tower.The present invention also comprises the laying method of above-mentioned earthing device.Adopt earthing device of the present invention and laying method thereof, construction is simple, and take up an area few, cost is low, can simple, reduce pole tower ground resistance cost-effectively.
Description
Technical field
The present invention relates to a kind of earthing device earthing device of metering device (and in apartment and flats) of 10kV distribution network overhead line tower pole, the invention still further relates to the laying method of described device.
Background technology
In power distribution network, overhead transmission line is widely distributed, and running environment is severe, very easily suffers direct stroke.Practical operating experiences shows, thunderbolt overhead transmission line causes switch trip to have a power failure, and accounts for significant proportion (lightning stroke trip accounts for 60 ~ 80% of total tripping operation number of times) in total accident of power distribution network.Meanwhile, the lightning overvoltage produced during thunderbolt circuit invades power equipment along circuit, is again the key factor causing insulation of electrical installation to damage.Therefore, in power distribution network, the lightning protection of overhead transmission line is most important.
Lightning protection, not only will consider improve the lightning withstand level of circuit and reduce the tripping rate with lightning strike of circuit, also should consider overall economic efficiency.That is will according to the electric pressure of circuit, significance level, pass through lightening activity degree of strength, topography and geomorphology feature and the soil resistivity situation in area, through technology, Economic contrast, choose more rational protected mode.
According to practical operating experiences display, existing lightning protection measures roughly comprises following a few class:
(1) lightning conducter is set up; (2) leakage conductor is installed; (3) pole tower ground resistance is reduced; (4) coupling ground wire is set up; (5) grounding through arc is adopted; (6) insulation level of equipment is improved; (7) unbalanced insulating method is taked; (8) install auto recloser line insulation and there is self-healing.(1)-(5) item lightning protection measures all relates to lightning protection problem above; Operative practice proves in recent years, and the size of earth resistance directly affects lightning protection level and the lightning protection effect of circuit; Therefore, the important step that earth resistance is Thunder Protection is reduced.
The application mainly inquires into the earth resistance problem how reducing 10kV distribution network overhead line tower pole, how by transformation earthing device, makes earth resistance meet the requirement of system docking earth resistance, and for the corresponding solution of proposition.
The meaning of the lightning protection of electric distribution network overhead wire
Lightning protection (overvoltage protection ground connection) be in order to eliminate thunderbolt and internal overvoltage danger and establish, as the ground connection etc. of the lightning arrester on overhead transmission line, lightning rod and lightning conducter.Earthing device: the down conductor of electric equipment is called earthing device with the summation of the metallic ground body group imbedded in ground.Earth electrode is the wandering part that earth current flows to soil, and the metallic conductor of earth electrode can be divided into two kinds: natural grounding substance and artificial earth electrode.Artificial earth electrode can horizontal laying also can vertical run.Steel pipe or angle steel are generally vertically be driven underground, and round steel, band steel mean level imbed underground.
No matter adopt the earthing mode of which kind of form, all must meet the requirement of system docking earth resistance, earth resistance is less, and the effect of ground connection is better.At present, normal earthing method and the existing problems of adopting have:
(1) wall scroll earth electrode is vertically driven underground (steel pipe, angle steel or round steel, the full-length of general earth electrode is 2 meters), and advantage is laid simply, and take up an area few, cost is low, and shortcoming is.Be difficult to the requirement reaching system docking earth resistance;
(2) round steel or band steel are welded into earth mat level and imbed underground, lay Manual earth network; Advantage can reach the requirement of system docking earth resistance; Shortcoming lays comparatively complexity, and occupation of land is many, and cost is high.
(3) mainly take when the earth resistance finding in original earth mat in running can not reach the requirement of system docking earth resistance: extend earth electrode method, add in soil and fall auxiliary agent, change soil method and draw earthing etc. outward.Due under the prerequisite of distribution network line grid structure basic forming, it is unrealistic that auxiliary agent falls in replacing soil and interpolation, most shaft tower is arranged in again rural area and ploughs, problem is paid for based on green grass or young crops, expropriation of land is too difficult, not earth mat reconstruction can be carried out, excavation for residential block is just completely unrealistic, and extend earth electrode cost too high, effect again not necessarily can be obvious, the Grounding Grids length that this method adopts, 5 ~ 10 meters are generally depending on geological conditions, more then DeGrain time long, and bring difficulty to construction, to sum up, these four kinds of methods are difficult to carry out.Summary of the invention
First technical problem to be solved by this invention, is just to provide a kind of earthing device of 10kV distribution network overhead line tower pole.
Second technical problem to be solved by this invention, is just to provide the laying method of above-mentioned earthing device.
Adopt earthing device of the present invention and laying method thereof, can simple, reduce pole tower ground resistance cost-effectively.
Solve above-mentioned first technical problem, the technical solution used in the present invention is:
A kind of earthing device of 10kV distribution network overhead line tower pole, the down conductor comprising electric equipment and the metallic ground body group imbedded in ground, it is characterized in that: described imbed metallic ground body group in ground and be made up of the iron ring earthing body being embedded in underground around shaft tower, level and at least 3 bar-shaped earth electrodes being vertically embedded in underground, be overlapped on ring earthing body after described earth electrode upper end bending, described down conductor lower end is connected electrically on ring earthing body, upper end then connects shaft tower.
Described ring earthing body is that band steel is made.
Described earth electrode vertical length is 2 meters (full-lengths of general earth electrode), and quantity is 5.
Described earth electrode and ring earthing body adopt antirust bolt to be connected or overlap and weld, and when adopting overlap joint welding, to round steel, the length of overlap joint is 6 times of its diameter, and two-sided welding, the lap of splice of band steel is 2 times of its width, and four sides welding.
The laying method of above-mentioned earthing device, comprises the following steps:
1, the interior edge of ring earthing body should apart from shaft tower 30-50cm, and the depth of burying is at 25-35cm; The earth electrode part depth of burying should be the best 2m of L=1.8-2.2m(), diameter gets Φ=18-20mm(the best 19) earth electrode.
2, first should bury earth electrode underground, then bury ring earthing body underground, and Site Welding completes, ensure that ring earthing body is regular, nothing is most advanced and sophisticated.
3, earth electrode should weld with ring earthing body, and welding should adopt overlap joint welding, and to round steel, the length of overlap joint should be 6 times of its diameter, and answers two-sided welding, and the lap of splice of band steel should be 2 times of its width.And should weld on four sides; Weld bond quality should must not meet the requirements rosin joint, dry joint phenomenon, and if this junction is as welded, available bolt connects, but should take reliable rust preventing.
4, the connection of down conductor and shaft tower is applied zinc-plated tying and is connect, and should contact good, so that open measurement of Grounding Resistance.
5, butt welding mouth wants pitching to carry out preservative treatment, to down conductor, from horizontal grounding objects junction until with the connecting bolt of shaft tower, whole brush pitch, or antirust paint and pitch-darkly carry out preservative treatment, because this part difference due to anti-corrosion potential the most easily chemical corrosion occurs.
6, backfill, when earth electrode all welds complete, anti-corrosion measure is also constructed complete, and on inspection after acceptance(check), could start backfill, backfill fine earth backfills, and must not have stone and building waste etc. in backfill soil, and the soil got outward must not have stronger corrosivity; Answer compaction in layers when backfill soil, ban the use of sandstone backfill.
7, floor treatment, after backfill. and being in hillside in this way, or area, slope, in order to prevent rain drop erosion from causing soil erosion, should planting turf protection on the earth's surface after backfill.
8, after all constructing, surveyed earth resistance through 7 days again and see whether reach designing requirement.
Beneficial effect: adopt earthing device of the present invention and laying method thereof, construction is simple, and take up an area few, cost is low, can simple, reduce pole tower ground resistance cost-effectively.
Accompanying drawing explanation
Fig. 1 is the front view of the earthing device embodiment of 10kV distribution network overhead line tower pole lightning arrester of the present invention;
Fig. 2 is the vertical view of Fig. 1;
Fig. 3 is the upward view of Fig. 1;
Fig. 4 is the earth resistance changing trend diagram of radial ground conductor and ring earthing body two kinds of earthing modes;
Fig. 5 is different earth electrode quantity pole tower ground resistance changing trend diagrams;
Fig. 6 is different depth pole tower ground resistance changing trend diagram.
In figure: 1-ring earthing body, 2-earth electrode, 3-down conductor.
Embodiment
As shown in Figure 1 to Figure 3, the earthing device most preferred embodiment of 10kV distribution network overhead line tower pole lightning arrester of the present invention, the down conductor 3 comprising electric equipment and the metallic ground body group imbedded in ground, imbed metallic ground body group in ground to be made up of the iron ring earthing body 1 being embedded in underground around shaft tower, level and 5 bar-shaped earth electrodes 2 being vertically embedded in underground, be overlapped on ring earthing body 1 after the upper end bending of earth electrode 2, the lower end of down conductor 3 is connected electrically on ring earthing body 1, ring earthing body is that band steel is made, and earth electrode vertical length is 2 meters.
The scheme reducing lightning protection resistance is explored
To the shaft tower of general height, the earth resistance reducing shaft tower improves line lightning resisting level, reduces the most economical effective method of tripping rate with lightning strike.Especially, in the soil of electricalresistivityρ≤300 Ω m, earth resistance is reduced comparatively easy, small investment.But in high soil resistivity, many radiations or continuous elongation shape earth electrode should be adopted.By regulation, the power frequency earthing resistance of every base shaft tower, when untiing lightning conducter, under humidity or drying regime, should not exceed data shown in table 1.
Table 1 overhead line structures power frequency earthing resistance
According to the requirement of electric pressure and the difference of soil resistivity, the form of earth electrode is also diversified, generally has following several:
1. in-line earth electrode: adopt and be laid in ground slot to several earth strips, is generally applied in the less area of soil resistivity and the lower circuit of electric pressure; Comprise metering device in apartment and flats.
2. ring earthing body: be the ring earthing body formed around shaft tower with band steel, be generally used for transmission line, the Electric Field Distribution of earth point soil can be improved.
When make use of still not meet earth resistance required value after natural grounding substance time, should artificial earth electrode be buried underground; And for without the available place of natural grounding substance, just must artificial earth electrode be buried underground.
According to above-mentioned comparison of design exploration be:
(1) during earth electrode radical n=3, the pole tower ground resistance variation tendency that a word is buried underground with annular.
According to above-mentioned Contact patch, 5 straight lines, the angle pole of choosing the different circuits of different location implement two kinds of earth electrode ground connection respectively, and the degree of depth is buried underground and is 2 meters, carries out grounding resistance measurement, obtains following table:
Pole tower ground resistance measures statistical form
According to upper table, make earth resistance changing trend diagram Fig. 4 of two kinds of earthing modes, as seen from Figure 4, annular is laid pole tower ground resistance and is obviously laid much lower than a word, and lightning protection effect also can be better.
(2) earth electrode radical respectively n=1(is single), 3,4,5,6,8 time, the earth resistance variation tendency that annular is buried underground.
According to above-mentioned Contact patch, choose 3 shaft towers (cement pole) and implement earth electrode ground connection respectively, the degree of depth is buried underground and is 2 meters, carries out grounding resistance measurement, obtains following table:
Pole tower ground resistance measures statistical form
According to upper table, different earth electrode quantity pole tower ground resistance changing trend diagram is as Fig. 5.
As seen from Figure 5, along with the increase of earth electrode quantity, earth resistance presents reduction trend, but is being greater than after 5, and change tends towards stability again, then increases earth electrode quantity, and earth resistance no longer reduces.As can be seen here, as ground connection number of poles two n=5, grounding resistance is minimum.
(3) during earth electrode radical n=1, earth electrode needs to be driven underground and many deeply just can be equivalent to n=5, and the degree of depth is the resistance value that the annular of 2 meters lays earth electrode.
Be benchmark according to the numerical value of scheme (2), the depth of burying from 2 meters to 6 meters (more difficult enforcement) carry out grounding resistance measurement, obtain following table:
Pole tower ground resistance measures statistical form
Different depth pole tower ground resistance variation tendency is shown in Fig. 6.
From upper table and Fig. 6, when single earth electrode buried depth is 4 meters, only have one group of earth resistance to be less than reference value, other three groups are all greater than reference value, and buried depth 4 meters is for construction, and more difficult operation, cost is higher, less economical.Moreover consider that earth electrode and soil contact amass, and electric discharge to require to let out electric channel instantaneously more short better, therefore, extending earth electrode, to reduce earth resistance uneconomical, safe not to reach the way discharging lightning current.
Conclusion
Through above-mentioned testing and verification, as n=5, take annular to lay grounding resistance that earth electrode can effectively reduce lightning protection, and the method is simple, for line thunder protection ground connection rectification and new clothes all without the need to excavating soil on a large scale, than laying, earth mat cost is much lower, good economy performance, than the single earth electrode degree of depth of extension, its fail safe reliability wants high a lot, therefore, think this kind of method herein, no matter from its reliability, fail safe, or from its economy, operability aspect all can yet be regarded as a kind of should vigorously promote the use distribution network line shaft tower lightning protection transformation new method.
The construction method of the earthing device of 10kV distribution network overhead line tower pole lightning arrester of the present invention, comprises the following steps:
1, the interior edge of ring earthing body should apart from shaft tower 30-50cm, and the depth of burying is at 25-35cm; The earth electrode part depth of burying should be the best 2m of L=1.8-2.2m(), diameter gets Φ=18-20mm(the best 19) earth electrode.
2, first should bury earth electrode underground, then bury ring earthing body underground, and Site Welding completes, ensure that ring earthing body is regular, nothing is most advanced and sophisticated.
3, earth electrode should weld with ring earthing body, and welding should adopt overlap joint welding, and to round steel, the length of overlap joint should be 6 times of its diameter, and answers two-sided welding, and the lap of splice of band steel should be 2 times of its width.And should weld on four sides; Weld bond quality should must not meet the requirements rosin joint, dry joint phenomenon, and if this junction is as welded, available bolt connects, but should take reliable rust preventing.
4, the connection of down conductor and shaft tower is applied zinc-plated tying and is connect, and should contact good, so that open measurement of Grounding Resistance.
5, butt welding mouth wants pitching to carry out preservative treatment, to down conductor, from horizontal grounding objects junction until with the connecting bolt of shaft tower, whole brush pitch, or antirust paint and pitch-darkly carry out preservative treatment, because this part difference due to anti-corrosion potential the most easily chemical corrosion occurs.
6, backfill, when earth electrode all welds complete, anti-corrosion measure is also constructed complete, and on inspection after acceptance(check), could start backfill, backfill fine earth backfills, and must not have stone and building waste etc. in backfill soil, and the soil got outward must not have stronger corrosivity; Answer compaction in layers when backfill soil, ban the use of sandstone backfill.
7, floor treatment, after backfill. and being in hillside in this way, or area, slope, in order to prevent rain drop erosion from causing soil erosion, should planting turf protection on the earth's surface after backfill.
8, after all constructing, survey earth resistance again through certain hour (7 days) and see whether reach designing requirement.
Claims (1)
1. the laying method of a 10kV distribution network overhead line tower pole earthing device, the down conductor that described earthing device comprises electric equipment and the metallic ground body group imbedded in ground, described imbed metallic ground body group in ground and be made up of the iron ring earthing body being embedded in underground around shaft tower, level and at least 3 bar-shaped earth electrodes being vertically embedded in underground, be overlapped on ring earthing body after described earth electrode upper end bending, described down conductor lower end is connected electrically on ring earthing body, upper end then connects shaft tower; Described ring earthing body is that band steel is made, and described earth electrode vertical length is 2 meters, and quantity is 5; Described earth electrode and ring earthing body adopt antirust bolt to be connected or overlap and weld; When adopting overlap joint welding, to round steel, the length of overlap joint is 6 times of its diameter, and two-sided welding; The lap of splice of band steel is 2 times of its width, and four sides welding;
Described method comprises the following steps:
Along distance shaft tower 30-50cm in S 1, ring earthing body, the depth of burying is at 25-35cm; The earth electrode depth of burying is L=1.8-2.2m, diameter gets Φ=18-20mm;
S 2, first bury earth electrode underground, then bury ring earthing body underground, and Site Welding or connect with bolt, ensure ring earthing body regular, without most advanced and sophisticated;
When S 3, earth electrode weld with ring earthing body and adopt overlapping mode, be 6 times of its diameter to the round steel lap of splice, and two-sided welding, the band steel lap of splice is 2 times of its width, and four sides welding;
The connection of S 4, down conductor and shaft tower connects with galvanized bolt;
S 5, butt welding mouth pitching carry out preservative treatment, to down conductor, from horizontal grounding objects junction until with the connecting bolt of shaft tower whole brush pitch or antirust paint, pitch-darkly carry out preservative treatment;
S 6, backfill: backfill fine earth, must not have stone and building waste in backfill soil, must not fetch earth outward and is corrosive; In the compacting of backfill soil layered, ban the use of sandstone backfill;
S 7, floor treatment: after backfill, be in hillside or area, slope and then plant on earth's surface turf;
After S 8, all construction, surveyed earth resistance through 7 days again and see whether reach designing requirement.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2022208422A1 (en) * | 2021-03-31 | 2022-10-06 | Terna S.P.A. | Grounding system for towers of overhead power lines |
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| CN104241879A (en) * | 2014-09-17 | 2014-12-24 | 辽河石油勘探局 | Construction technology of earthing device of lightning arrester |
| CN104201484A (en) * | 2014-09-19 | 2014-12-10 | 国家电网公司 | No-screw non-welded mesh ground lead |
| CN105514627A (en) * | 2014-09-26 | 2016-04-20 | 上海市南供电设计有限公司 | Grounding disc device used for concrete telegraph pole |
| CN105514750A (en) * | 2015-11-19 | 2016-04-20 | 国家电网公司 | Power transmission line grounding construction method |
| CN109378601A (en) * | 2018-11-27 | 2019-02-22 | 国网新疆电力有限公司喀什供电公司 | Adjustable grounding pin |
| CN110444919B (en) * | 2019-09-19 | 2020-10-23 | 国网青海省电力公司黄化供电公司 | Permanent pre-buried grounding body of urban distribution network and construction method thereof |
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| CN112580697B (en) * | 2020-12-04 | 2023-05-26 | 国网山东省电力公司电力科学研究院 | Power transmission line tower grounding selection method and system |
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