电气专业毕业设计外文翻译--防雷接地

Lightning protection grounding

Abstract The significance of lightning p.rotection and mitigation on very little money to prevent large losses, and its function is to use scientific means avoid natural disasters. Grounding is to make the system has been included in the lightning protection lightning energy discharge into the earth, and good grounding can effectively reduce the online guide overvoltage, avoid counterattack. Avoid ground is the most important aspect of technology, whether sings rem, induction lightning, or other forms of ray, ultimately the lightning current into the earth. Therefore, no reasonable and good grounding device is can't reliably the lightning strikes. The smaller the grounding resistance, come loose flow is quicker, lightning objects the time to maintain high potential more short, the less risk

Key W ords:Lightning protection; Grounding; Current; potential

1 introduction

In recent years, many domestic and foreign standards do not advocate information equipment using independent grounding device, recommend the use of common earthing system. For example, the 2000 edition of the GB50057-94" design code for protection of structures" in point out clearly:" every building itself should adopt common earthing system" to be the buildings within the various grounding are unified to buildings based on, or outdoor grounding device. When the building was hit by lightning, power system voltage and electrical equipment grounding voltage rises at the same time, keep the equipment working voltage constant, so that the electronic equipment from lightning strikes can work normally. Common earthing system usually use the building foundation grounding electrode, the grounding resistance less than 1 ohm in general, if the equipment grounding resistance requirement is lower, should take the minimum value.

The ground that has been incorporated into the lightning protection system of lightning energy drain into the earth, good grounding downlead to effectively reduce the voltage on the back, to avoid the occurrence of. In the past some requirements of electro nic equipment grounding alone, the purpose is to prevent stray current and transient current in power network disturbance of the normal work of equipment. Before 90 time, forces of the communication navigation equipment electronic tube device, using analog communication mode, analog communication on particularly sensitive to interference, interference, so will take power and communications grounding separate way. Now, the lightning protection engineering fields do not advocate a separate ground. In the IEC standards and ITU standards are not advocating a separate ground, American Standard IEEEStd1100-1992more sharply pointed out: not recommended the use of any kind of so-called separate, independent,

computer, electronic or other such incorrect ground as equipment grounding conductor of a connection point. Grounding is the most fundamental aspect of the lightning protection system. The ground is not good, all the measures of lightning protection effect can play. Lightning protection grounding is ground communication station

Code for construction and acceptance of the basic safety requirements, the grounding of PLC belongs to a low-voltage electrical equipment of single point grounding mode

Low voltage electrical equipment of single point grounding mode can be divided into: tandem type single point grounding, parallel type single point grounding, multiple branching of single point grounding.

2 single point grounding method

Tandem type single point grounding: or first grounding ways. Method : the number of low voltage electrical equipment grounding terminal equipment with the same root near the ground wire connecting, then through this grounding and grounding device. The grounding system is: save manpower, material resources; while the disadvantage is that: when the public grounding line open circuit, if the grounding system has a device leakage, can cause other equipment which occurred on voltage, a threat to the safety of personnel.

B ackup ground terminal introducing a grounding line, and then the number of lines at the same time received a grounding device. The grounding system is: when the grounding system in which a device grounding wire broken circuit, will not cause other equipment enclosure voltage, to ensure personal safety. This grounding mode is: if it is not perfect on the interference of high frequency electronic equipment or other highly sensitive electrical equipment, high frequency interference from other devices ( such as converter, intermediate frequency stove thyristor converter parts) will be from the common place of string, causing the device is not working properly.

Multiple branching of single point grounding: or third grounding ways. Grounding method: each equipment grounding terminal alone received a grounding device. Earthing method and second kinds of grounding is the difference: the device has a separate grounding body ( or a change of: received directly from the grounding body recent grounding device ( or grounded source office ), each device in the electrical ground loop on the distance is far more (for example, more than 50meters ) ). This effectively avoids the mutual electrical equipment

Magnetic interference.But this grounding mode time-consuming, laborious and separate grounding the source is not good for.

In the usual construction, in fact the grounding of PLC way adopts the second grounding ways, as for electromagnetic interference: if the cabinet is provided with a plurality of high power frequency converter, can be in the PLC power supply is installed in front of a single-phase power filter can be, generally designed in the inverter PLC near the front end are equipped with power supply filter.

The interference effect of DC and AC equipment, can be connected together -- even if the DC and AC circuits because of some reason connectivity, because they are not the same as a loop ( grounding is not part of the loop ), will not cause damage to the equipment. People have AC220V power and DC24V circuit connected to it, but the equipment work remains normal.

Digital and analog ground suggested separately ( unless you're a low-voltage electrical equipment power supply voltage only a few tens of volts ), because the digital circuit belongs to positive and negative 5V,12V,24V level, are vulnerable to interference, and once the external abnormal voltage once the series will very possible equipment damage. I just go to work in the factory has a 1000 tons of SACMI press, because other equipment and digital ground causes the electronic facilities burned down last several times, Italy sent technicians ( just graduated from secondary school students ) and replacement equipment, conductor of the in situ dug a pit, buried a piece of ground the brass and the earthing filler, engage in a separate grounding.

3 Lightning proof grounding device for part of a concept

(1) Lightning receiving device directly or indirectly accept the lightning rod ( flash ), such as lightning, lightning protection zone ( net ), overhead ground wire and arrester. (2) lead: for the lightning current from the lightning arrester is conducted to the grounding conductor.

(3) grounding: electrical equipment, tower grounding terminal and a grounding body or the zero line connected with the normally not current-carrying metal conductor.(4) grounding body ( polar ): buried in the soil and directly touch the earth metal conductor, known as the grounding body. Divided into vertical grounding electrode and level of grounding body.(5): grounding device grounding and grounding. (6): grounding grid by vertical and horizontal grounding body composition having discharge and pressure equalizing function network grounding device. (7): grounding resistance of grounding body or natural grounding resistance to the ground of the sum, a grounding device resistance, its value is equal to the grounding device of voltage to the ground and through the grounding body into ground current ratio. At the same time the grounding resistance of grounding device is a constant level indication.

4 The grounding device is easy to corrosion location mainly

(1) equipment grounding downlead and connecting screws; (2) each welding head; (3) cable channel equalizing zone; (4) the horizontal grounding body,Anti corrosion measures,grounding body using copper, copper clad steel earth body or hot galvanized materials; welding brush asphalt paint or powder coating; use of cathodic protection.

One, ground resistance test requirements: a. AC grounding, grounding resistance should be less than4 ohm; b. Safety grounding, grounding resistance should be less than4 ohm; C DC grounding, grounding resistance should be according to the computer system specific requirements determined; lightning protection to D. Grounding resistance should be less than10 ohm; e for shielding system if the joint grounding, grounding resistance should not be greater than1 ohms.

Two, ground resistance tester ZC-8grounding resistance meter is used for measuring the power system, electrical equipment, lightning and grounding resistance value. Also measuring low resistance conductor resistance and resistivity of soil.

In three, the instrument by hand generator, current transformer, a slide wire resistor and galvanometer etc., all arranged in the plastic shell body, and the shell is convenient for carrying. Accessory auxiliary probe wires, installed in the accessory bag.The working principle of the voltage comparing type.

I n four, before use to check whether the complete tester, tester comprises the following device. In 1, ZC-8 type grounding resistance tester, a2auxiliary grounding rods two root of 3,5m,20m,40m wire a

Ground resistance tester, usually hand ZC-XX series, including a short black lines, a20M line, a40M line, testing line connected at one end of a tested object whose the other end is connected with a shake table on each of two short connecting terminals, and the remaining 2terminal 20M line with P terminal,40M line C terminal to terminal, after the 20M and 40M line according to the ribbon (that is, to shake table for the endpoint of a triangle ) or linear completely out, hit good probe. In the shake table select file and then to 120RPM speed swing table, side table edge with a shake shake table can dial0, until the pointer on a shake table center scale 0, with stalls multiplied by the dial corresponding numerical result this grounding grounding resistance.

Wire grounding is an important electrical safety technical measures, the operation should be serious, serious, comply with the requirements of technical specifications, must not be careless. Therefore, correctly use the ground, normative hanging, remove grounding behavior, consciously cultivate rigorous safety work style, improve their awareness of safety, to resist

the danger from thousands of miles away, in order to avoid the ground causes electrical accident.

A ccording to the practical work, ground use should pay attention to the following matters.

1work must be checked before grounding wire. Soft copper wire is broken, the screw loose connections, hook line stretch is normal, do not meet the requirements should be replaced or repaired before use.

2 hanging wire must be a priori power, not checking cable grounding is the base of common habitual violations, in suspension when the grounding body and physical contact.

3 in the work place two segment ends hanging earthing, lest the user would send electric, induction electricity, suffer a number of examples.

4 in the play ground pile, you should dial can borrow to physical fast dredge accident current, grounding the quality guarantee.

5to protect the earth. Grounding wire in use in the process may not be twisted, should not soft copper wire wheel, grounding in removed, not from the air leaving or anywhere to fall, use rope transfer, pay attention to ground cleaning work.

6new staff must go through ground wire using the training, learning, after passing the examination, can the individual engaged in ground operation or use of the work.

According to the different voltage levels corresponding to7specifications of the grounding wire selection.

8prohibited the use of other metal wire instead of grounding wire.

The 9 grounding wire has two sides, it has a safety function, improper use will produce destructive effect, so after work to timely removal of ground wire. With the earthing switch may damage electrical equipment and the destruction of the power grid stability, can lead to severe malignant electric accident.

10field work not less hanging earthing conductor or alter the articulated ground location.

5 Lightning protection system construction methods and technical measures

Lightning protection system grounding engineering major required close coordination, interspersed with civil completed. In civil unit beam, column and reinforced structure modeling is to follow up the grounding body ( line ) of the lap welding and grounding lead welding. In order to prevent the welding fault leakage, during each lightning protection on the ground ( body ) after welding, are on the main reinforcement is painted in eye-catching mark, for the benefit of a layer.Wire, mesh welding.Lightning protection construction method

According to the design institute to provide the drawings, using the foundation steel (including pile steel mesh cage bars ) as the lightning protection and grounding, using column within 2main bar as lead, using concrete foundation beam reinforced bar as electrode connection, use of roof beam reinforcing steel bar and reinforced parapet coping as dark installed lightning protection belt.Flank-Striking lightning protection construction method:

1straight buried metal pipes and metal top and lightning protection device.

2into the building of buried metal pipeline, roof all the metal pipeline and its structure also and lightning protection device.

3note that in the construction of grounding body ( line ) of the lap length must comply with the following provisions:

3.1flat to2 times its width ( and at least 3edge welding);

3.2bar is connected by double lapped continuous welding of https://www.360docs.net/doc/6411331474.html,, weld length not less than 6 times the diameter, good weld appearance;

3.3round steel and flat steel connections, its length is6 times the diameter of round steel;

3.4flat steel and steel, flat steel and angle steel welding, in order to reliable connection, except in the contact area on both sides of the welding, and welding to steel bent into arc ( or angle ) clips or directly by the strip itself curved surface arc ( or angle ) and steel ( or angle ) welding.

3.5 exposed lightning strip galvanized special clamping support code support, avoid the support member and lightning belt welding.

3.6steel pipe for lightning protection grounding device (including needle, etc. ), tube wall thickness not less than2.5mm. The butt welding of the tube, pipe is provided suitable liner pipe diameter. And connecting pipe diameter dovetails, lining length not less than4 times the outside diameter.

From3.7in the first layer of ground1.51.8m leads to easy operation and maintenance of the permanent test. Test points are obvious grounding mark and reliable and anti-corrosion measures.

The 3.8grounding resistance should be performed to detect, plus or minus 0part test point were tested individually, + 0above part can use test point of each of the three layer is a detection, i.e. each completed a lightning arrester grading ring or band is installed you can use e lectrode leading-out wire of a test work. The grounding resistance measurement requirements of less than 1ohm.

6 Lightning protection engineering construction quality defects and Its Countermeasures

Roofing exposed metal pipe and equipment and component without lightning protection connection, or the connection does not meet the requirements, there is the potential for harm of thunder and lightning.Construction countermeasures:1strictly implement the" design code for protection of structures" ( GB5005794) concerned regulation, ensure the impulse grounding resistance to meet the requirements.The 2connecting leads not directly in galvanized steel pipe welding, suitable for welding or bolt connection in the special grounding wire card ( or metal pipe bracket ).The 3lightning protection connection lead should be concealed, grounding bar welding not fusion, resulting in effective contact area is reduced, the lightning will fuse risk.Construction countermeasures:Construction should pay attention to the appropriate electrode angle, swing, pay attention to the melting of lap joints on both sides.,Earthing and equipotential connection:1 all electrical equipment metal shell, frame, line pipe, cable bridge must have good ground, make it a good grounding path.2used for outdoor grounding bar welding length not less than 6times the diameter of round steel, flat steel two surface welding; the connection between the flat width for2 times, three surface welding; round steel and flat steel bar connection for6 times, two surface welding.3potential galvanized round steel welded beam in foundation of the main grounding bar, and small ground lines are connected, in the connection equipotential box galvanized plate, welding seam must be full. Indoor draught to the equipotential box is connected with the circuit to be connected is complete, the grounding wire specifications of not less than 4mm2, and ensure reliable contact.4 ground connection of all welds must oil antirust paint two times ( with the exception of concrete structure welding ); galvanized grounding bar, flat steel in the underground buried depth should not be less than0.8m.

7 Importance of grounding and lightning grounding resistance testing

Lightning protection and grounding technology,In order to solve the communication network (including the user terminal ) overvoltage protection for the purpose, has developed a variety of lightning protection and grounding technology, these are to ensure the reliability of telecommunication network technology, is the important basic technology in the field of communication. Now commonly used by telecommunications building integrated earthing( grounding ) and introduces a variety of lightning protection device. But, now has access to the optical fiber communication era, even in the communication network of the user terminal, at the same time, and connected to an AC power line, at the user terminal using the large scale integrated circuit is more and more, the new features of the lightning protection and grounding, raised new requirement, we must try to adapt to these new characteristics.Grounding resistance test technology.

In recent years, because of digital technology and the development of optical communication technology, so that the original installation in a telephone exchange part of the exchange, transmission equipment to the user mobile, and often these devices are mounted to the general residential buildings and overhead, so ask them with the telephone exchange room floor with.The shielding effect, it is obviously not possible, then how to do? Now hand requires these devices improve the adaptability, on the other hand, in order to prevent the leakage of electricity and lightning voltage on human body and equipment hazards, gro unding and lightning protection is vital.From the grounding purposes, especially for outdoor equipment grounding, leakage current and lightning protection is particularly important. The grounding resistance requirements, technical standards are clearly defined, it is. In order to ensure that the grounding resistance value to meet the requirement, after construction of the grounding resistance testing work is very necessary. But with the progress of the modernization of city, now the city roads and sidewalks are all concrete pavement asphalt pavement or covered now, if still use auxiliary electrode method to test the ground resistance, it is difficult to too much. The new ground resistance test method are introduced.In 1, the existing ground resistance test method.Wire grounding resistance is equal to the grounding electrode potential and the injected current ratio. The current earth resistance test method, as shown in figure 1. Where E is the grounding electrode, C is injected into the current of the auxiliary electrode, P is to test the potential of the auxiliary electrode imaginary reference point. Test, signal device in the E ~ C electrode with500 ~ 2KHz AC current by the dotted line into a flow, a current meter and a voltage meter readings, we can find the grounding resistance value.

In order to test the value of accurate, the distance between the electrodes shall be not less than 10meters. The distance, in the downtown area of the city, is often difficult to do.

防雷接地

摘要防雷减灾的意义在于用很少的钱预防大的损失，其作用在于使用科学的手段规避自然灾害。接地就是让已经纳入防雷系统的闪电能量泄放入大地，良好的接地才能有效地降低引下线上的过电压,避免发生反击。接地是避雷技术最重要的环节，不管是直击雷、感应雷、或其他形式的雷，最终都是把雷电流送入大地。因此，没有合理而良好的接地装置是不能可靠地避雷的。接地电阻越小，散流就越快，被雷击物体高电位保持时间就越短，危险性就越小。

关键词：防雷;接地;电流;电位

1 介绍

近年来，很多国内外的标准不主张信息设备采用独立的接地装置，推荐采用共用接地系统。例如，2000版的GB50057-94《建筑物防雷设计规范》中明确指出：“每幢建筑物本身应采用共用接地系统”即将建筑物内的各种接地都统一接到建筑物的基础上，或室外的接地装置上。当该建筑物遭受雷击时，电力系统的电压和电子设备工作接地的电压同时上升，保持了设备的工作电压不变，使电子设备在雷击时可正常工作。共用接地系统通常利用建筑物的基础做接地极，其接地电阻一般在1欧姆以下，如有设备对接地电阻的要求更低，应取其最小值。

接地就是让已经纳入防雷系统的闪电能量泄放入大地，良好的接地才能有效地降低引下线上的电压,避免发生反击。过去有些规范要求电子设备单独接地，目的是防止电网中杂散电流或暂态电流干扰设备的正常工作。90年代以前，部队的通信导航装备以电子管器件为主，采用模拟通信方式，模拟通信对干扰特别敏感，为了抗干扰，所以都采取电源与通信接地分开的办法。现在，防雷工程领域不提倡单独接地。在IEC标准和ITU 相关标准中都不提倡单独接地，美国标准IEEEStd1100-1992更尖锐地指出:不建议采用任何一种所谓分开的、独立的、计算机的、电子的或其它这类不正确的大地接地体作为设备接地导体的一个连接点。接地是防雷系统中最基础的环节。接地不好，所有防雷措施的防雷效果都不能发挥出来。防雷接地是地面通信台站安装验收规范中最基本的安全要求，PLC的接地属于低压电器设备的

2单点接地方式

低压电器设备的单点接地方式可分为：串联式单点接地、并联式单点接地、多分支单点接地。

串联式单点接地：也就是第1种接地方式。接地方法：将多个低压电气设备的接地端子在设备的就近处与同一根接地线连接上，然后通过这根接地线与接地装置连接。这种接地方式的好处在于：节省人力、物力；而坏处在于：当公用的接地线出现断路时，

如果接地系统中有一台设备漏电，就会引起其它设备的外壳上均出现电压，对人员安全造成威胁。

后备的接地端子都引出一根接地线，然后将这若干条线同时接到接地装置上。这种接地方式的好处在于：当接地系统中的其中一台设备接地线出现断路时，不会造成其它设备外壳出现电压，对保障人身安全有好处。而这种接地方式的不完美之处在于：如果是电子设备或其它对高频干扰高度敏感的电气设备，来自于其它设备的高频干扰（例如变频器、中频炉等晶闸管变流器件）将会从共地点串入，造成设备工作不正常。

多分支单点接地：也就是第3种接地方式。接地方法：将每个设备的接地端子单独接到接地装置上。接地方法和第2种接地的区别在于：设备具有单独的接地体（或者变通一下：直接接到离接地体最近的接地装置上（或者接地源处），每个设备在电气接地回路上的距离是比较远的（例如超过50米））。这有效的避免了设备之间的相互电磁干扰。但这种接地方式费时、费力而且单独接地源不一定好取。

在平常施工中，实际上PLC的接地方式一般采用第2种接地方式，至于电磁干扰方面：如果柜内有多个大功率的变频器，可以在PLC电源的前端加装一个单相电源滤波器就可以了，一般设计时在变频器附近的PLC前端都加装了电源滤波器。

对于受干扰影响不大的直流和交流设备，可以接在一起——即使直流和交流电路因为某种原因连通了，因为他们不是同一个回路（接地可不是回路中的一部分），也不会造成设备损坏。曾有人将AC220V的电源与DC24V回路连上了，但设备工作仍然正常。

数字地和模拟地建议分开（除非你的低压电气设备电源电压只有几十伏），因为数字电路属于正负5V、12V、24V级别的，很容易受干扰，而且一旦外部异常电压一旦串入将很大可能性的造成设备损坏。我刚上班时工厂里有一台1000吨的萨克米压砖机，因为其它设备和数字地的原因导致其电子设施几次烧毁，最后意大利派过来的技师（才毕业的中专生）更换设备后，指挥人在就地挖了个坑，埋了一根接地铜管和接地填料，搞成了单独接地。

3防雷接地装置部分概念

(1)雷电接受装置：直接或间接接受雷电的金属杆（接闪器），如避雷针、避雷带（网）、架空地线及避雷器等。

(2)引下线：用于将雷电流从接闪器传导至接地装置的导体。

(3)接地线：电气设备、杆塔的接地端子与接地体或零线连接用的正常情况下不载流的金属导体。

(4)接地体（极）：埋入土中并直接与大地接触的金属导体，称为接地体。分为垂直接地体和水平接地体。

(5)接地装置：接地线和接地体的总称。

(6)接地网：由垂直和水平接地体组成的具有泄流和均压作用的网状接地装置。

(7)接地电阻：接地体或自然接地体的对地电阻的总和，成为接地装置的接地电阻，其数值等于接地装置对地电压与通过接地体流入地中电流的比值。同时接地电阻也是恒量接地装置水平的标志。接地装置容易发生腐蚀的部位主要有：(1)设备接地引下线及其连接螺丝；(2)各焊接头；(3)电缆沟内的均压带；(4)水平接地体

4防腐蚀措施

接地体采用铜材、铜包钢接地体或热镀锌材料；焊接处刷沥青漆或银粉漆；采用阴极保护。

一、接地电阻测试要求： a. 交流工作接地，接地电阻不应大于4Ω； b. 安全工作接地，接地电阻不应大于4Ω； c. 直流工作接地，接地电阻应按计算机系统具体要求确定； d. 防雷保护地的接地电阻不应大于10Ω； e. 对于屏蔽系统如果采用联合接地时，接地电阻不应大于1Ω。

二、接地电阻测试仪 ZC-8型接地电阻测试仪适用于测量各种电力系统，电气设备，避雷针等接地装置的电阻值。亦可测量低电阻导体的电阻值和土壤电阻率。

三、本仪表工作由手摇发电机、电流互感器、滑线电阻及检流计等组成，全部机构装在塑料壳内，外有皮壳便于携带。附件有辅助探棒导线等，装于附件袋内。其工作原理采用基准电压比较式。

四、使用前检查测试仪是否完整，测试仪包括如下器件。 1、ZC-8型接地电阻测试仪一台 2、辅助接地棒二根 3、导线5m、20m、40m各一根

接地电阻测试仪，一般是手摇的ZC-XX系列的，包括一根黑色短线，一根20M线，一根40M线，测试时用短线一端连接被测试的物体另一端接摇表上两个相互短接的端子，另外剩余的2个端子20M线接P端子，40M线接C端子，待接线完毕后把20M和40M的线按带状（也就是以摇表为端点的一个三角形）或者直线完全放出去，打好探针。在摇表上选好档位然后以120转/分的速度摇动摇表，边摇摇表边用摇表上可刻度盘调0，待指针正对摇表中心刻度0时，用档位乘以刻度盘对应的数值得出此接地点的接地电阻。

挂接地线是一项重要的电气安全技术措施，其操作过程应该严肃、认真、符合技术规范要求，千万不可马虎大意。因此，要正确使用接地线，规范挂、拆接地线的行为，自觉培养严谨的安全工作作风，提高自身的安全素质，才能拒危险隐患于千里之外，才能避免由于接地线原因引起的电气事故。现根据实际工作中接地线的使用应注意以下事项：(1)工作之前必须检查接地线。软铜线是否断头，螺丝连接处有无松动，线钩的弹力是否正常，不符合要求应及时调换或修好后再使用。 (2)挂接地线前必须先验电，未验电挂接地线是基层中较普遍的习惯性违章行为，在悬挂时接地线道体不能和身体接触。

(3)在工作地点两段两端悬挂接地线，以免用户倒送电、感应电的可能，深受其害的例子不少。(4)在打接地桩时，要拨能借地体能快速疏通事故大电流，保证接地质量。(5)要爱护接地线。接地线在使用过程中不得扭花，不用时应将软铜线盘好，接地线在

拆除后，不得从空中丢下或随地乱摔，要用绳索传递，注意接地线的清洁工作。(6)新工作人员必须经过对接地线使用的培训、学习，考核合格后，方能单独从事接地线操作或使用工作。(7)按不同电压等级选用对应规格的接地线。(8)严禁使用其它金属线代替接地线。(9)接地线具有双面性，它具有安全的作用，使用不当也会产生破坏效应，所以工作完毕要及时拆除接地线。带接地线合开关会损坏电气设备和破坏电网的稳定，会导致严重的恶性电气事故。(10)现场工作不得少挂接地线或者擅自变更挂接地线地点。5防雷系统施工方法及技术措施

防雷系统接地工程主要需与土建密切配合、穿插完成.在土建单位进行梁、柱钢筋结构造型时即需跟进完成接地体（线）的搭接焊及接地体的引出焊接.为了防止焊接的错漏，在每次完成防雷引上接地线（体）焊接后，均在引上的主筋上端涂上醒目标记，以利上一层接地线、网的焊接。防直击雷施工方法：根据设计院提供的图纸，利用基础钢筋（包括桩钢筋网猪笼筋）作为防雷接地，利用柱内2条主钢筋作为引下线，利用砼基础梁钢筋作为地极连线，利用屋面梁钢筋及女儿墙压顶钢筋作为暗装避雷带。防侧击雷施工方法：

(1)直敷设的金属管道及金属物的顶端与防雷装置连接.

(2)进入建筑物的埋地金属管道、屋面所有金属管道及其构架亦与防雷装置连接.

(3)在施工中注意接地体（线）的搭接长度必须符合下列规定：

○1扁钢为其宽度的2倍（且至少3个棱边焊接）；

○2圆钢连接采用双面搭接连续焊https://www.360docs.net/doc/6411331474.html,，焊缝长度不小于直径的6倍，焊缝外观良好；

○3圆钢与扁钢连接时，其长度为圆钢直径的6倍；

○4扁钢与钢管、扁钢与角钢焊接时，为了连接可靠，除应在其接触部位两侧进行焊接外，并应焊以由钢带弯成的弧形（或直角形）卡子或直接由钢带本身弯面弧形（或直角形）与钢管（或角钢）焊接.

○5外露的避雷带采用热镀锌的专门夹式支持码支持，避免支持件与避雷带焊接.

○6用钢管作防雷接地装置（含针、带等）时，管壁厚不小于2.5mm.管对接焊时，管内设置合适的衬管.衬管外径与被连接钢管内径相吻合，衬长度不小于其外径的4倍.

○7在距首层地面1.5－1.8m引出易于操作维护的永久性测试点.测试点有明显的接地标志及可靠的防损防腐措施.

○8接地电阻应进行检测，±0.00以下部分利用测试点单独进行测试，±0.00以上部分可以利用测试点每三层进行一次检测，即每完成一次防雷均压环或避雷带的安装即可利用地极引出线进行一次测试工作.接地电阻实测要求小于1欧姆.

6防雷工程施工质量通病及其对策措施

屋面外露金属管道及设备与构件未进行防雷连接、或连接不符合要求，存在雷电危害隐患。施工对策：

(1)严格执行《建筑物防雷设计规范》（GB50057－94）的有关规定，保证冲击接地电阻符合要求.

(2)连接引线不宜直接在镀锌钢管上焊接，宜用焊接或螺栓连接在专用接地线卡上（或金属管道支架上）.

(3)防雷连接引线宜采用暗敷，接地圆钢焊接时焊缝未熔合，造成有效接触面积减少，雷击时会有熔断的危险。接地及等电位连接：

(1)所有电气设备金属外壳、构架、线管，电缆桥架必须有良好的接地，使其成为良好接地通路.

(2)用作室外接地连接的圆钢焊接长度不少于6倍圆钢直径，二面施焊；扁钢之间连接为扁钢宽度2倍，三面施焊；圆钢与扁钢连接为圆钢6倍，二面施焊.

(3)等电位镀锌圆钢必须焊接在基础地梁主接地钢筋上，并与小区接地干线相连，在连接等电位箱内镀锌板时,焊接焊缝必须饱满.室内引至该等电位箱连接的回路必须连接齐全，各接地铜线规格不少于4mm2，并确保接触可靠.

(4)接地连接的所有焊口必须油防锈漆二遍（混凝土结构内焊口除外）；镀锌接地圆钢、扁钢在地下的埋设深度不应少于0.8m.

7防雷接地的重要性及接地电阻测试

雷电防护及接地技术，以解决通信网络（含用户终端）的过电压保护为目的，现已开发出了各种各样的雷电防护及接地技术，这些都是确保通信网络可靠性的重要技术，也是通信领域中重要的基础技术。现已普遍采用的电信大楼综合接地（一点接地）和引入的各种防雷器。但是，现在已进入到光纤通信时代，连在通信网上的用户终端，同时还要与交流电源线相连，在用户终端上采用的大规模集成电路愈来愈多，这此新特点对雷电防护和接地，提出了新要求，我们必须设法去适应这些新特点。

接地电阻测试技术，近些年来，由于数字技术和光通信技术的发展，使原来安装在电话局内的一部分交换、传输设备向用户侧移动，并常把这些设备安装到一般住宅楼内和架空处，因此再要求它们与电话局的机房楼有相同的屏蔽效果，那显然是不可能的，那么该怎么办呢?现在一方面要求这些设备提高适应性，另一方面，为了防止漏电和雷电压对人身和设备的危害，接地技术和雷电防护就至关重要。

从接地的目的来看，特别是对室外设备接地，防漏电和防雷电就显得特别重要。对它们的接地电阻要求，技术规范上都有明确的规定，照办就是了。为了保证接地电阻值符合规范要求，施工后的接地电阻的测试工作就非常有必要。但是随着城市现代化的进

展，现在城市的道路和便道全都被沥清路面或混凝土路面所覆盖，现在若仍采用辅助电极法去测试地线电阻，实在是困难太多了。下面将对新旧地线电阻测试方法进行一下介绍，现行的地线电阻测试法，地线的接地电阻等于接地电极的电位与注入的电流的比值。现行的地线电阻测试方法。其中E是接地电极，C是注入电流用的辅助电极，P是为了测试电位用的辅助电极假想的参考点。测试时，信号器在E~C电极间加上500~2KHz的交流电流就按图中虚线进得流动，由电流表和电压表上的读数，就可求出地线电阻值。

为了测试值的准确，要求各电极间的距离不得小于10米。这个距离要求，在大城市的市区，往往难以作到。新的地线电阻测试原理， E为接地电极，金属板为电流回归路，测试由接地电极、大地、金属板和测试线构成的闭合回路的阻抗，可推算出地线的接地电阻。该方法很适合于城市中采用。