【正文】 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 equipmentMagnetic this grounding mode timeconsuming, 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 singlephase 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 you39。 Grounding。 welding brush asphalt paint or powder coating。 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. exposed lightning strip galvanized special clamping support code support, avoid the support member and lightning belt welding. pipe for lightning protection grounding device (including needle, etc. ), tube wall thickness not less . 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. the first layer of leads to easy operation and maintenance of the permanent test. Test points are obvious grounding mark and reliable and anticorrosion measures.The 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, . each pleted a lightning arrester grading ring or band is installed you can use electrode leadingout wire of a test work. The grounding resistance measurement requirements of less than 1ohm.6 Lightning protection engineering construction quality defects and Its CountermeasuresRoofing exposed metal pipe and equipment and ponent without lightning protection connection, or the connection does not meet the requirements, there is the potential for harm of thunder and countermeasures:1strictly implement the design code for protection of structures ( GB5005794) concerned regulation, ensure the impulse grounding resistance to meet 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 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 for outdoor grounding bar welding length not less than 6times the diameter of round steel, flat steel two surface welding。關(guān)鍵詞：防雷。過去有些規(guī)范要求電子設(shè)備單獨(dú)接地，目的是防止電網(wǎng)中雜散電流或暫態(tài)電流干擾設(shè)備的正常工作。接地方法：將多個(gè)低壓電氣設(shè)備的接地端子在設(shè)備的就近處與同一根接地線連接上，然后通過這根接地線與接地裝置連接。這有效的避免了設(shè)備之間的相互電磁干擾。 　　(2)引下線：用于將雷電流從接閃器傳導(dǎo)至接地裝置的導(dǎo)體。接地裝置容易發(fā)生腐蝕的部位主要有：(1)設(shè)備接地引下線及其連接螺絲；(2)各焊接頭；(3)電纜溝內(nèi)的均壓帶；(4)水平接地體4防腐蝕措施接地體采用銅材、銅包鋼接地體或熱鍍鋅材料；焊接處刷瀝青漆或銀粉漆；采用陰極保護(hù)。 ZC8型接地電阻測(cè)試儀一臺(tái) 輔助接地棒二根 導(dǎo)線5m、20m、40m各一根 接地電阻測(cè)試儀，一般是手搖的ZCXX系列的，包括一根黑色短線，一根20M線 ，一根40M線，測(cè)試時(shí)用短線一端連接被測(cè)試的物體另一端接搖表上兩個(gè)相互短接的端子，另外剩余的2個(gè)端子20M線接P端子，40M線接C端子，待接線完畢后把20M和40M的線按帶狀（也就是以搖表為端點(diǎn)的一個(gè)三角形）或者直線完全放出去，打好探針。(4)在打接地樁時(shí)，要撥能借地體能快速疏通事故大電流，保證接地質(zhì)量。(10)現(xiàn)場(chǎng)工作不得少掛接地線或者擅自變更掛接地線地點(diǎn)。現(xiàn)已普遍采用的電信大樓綜合接地（一點(diǎn)接地）和引入的各種防雷器?，F(xiàn)行的地線電阻測(cè)試方法。該方法很適合于城市中采用。但是隨著城市現(xiàn)代化的進(jìn)展，現(xiàn)在城市的道路和便道全都被瀝清路面或混凝土路面所覆蓋，現(xiàn)在若仍采用輔助電極法去測(cè)試地線電阻，實(shí)在是困難太多了。施工對(duì)策：(1)嚴(yán)格執(zhí)行《建筑物防雷設(shè)計(jì)規(guī)范》（GB50057－94）的有關(guān)規(guī)定，保證沖擊接地電阻符合要求.(2)連接引線不宜直接在鍍鋅鋼管上焊接，宜用焊接或螺栓連接在專用接地線卡上（或金屬管道支架上）.(3)防雷連接引線宜采用暗敷，接地圓鋼焊接時(shí)焊縫未熔合，造成有效接觸面積減少，雷擊時(shí)會(huì)有熔斷的危險(xiǎn)。(9)接地線具有雙面性，它具有安全的作用，使用不當(dāng)也會(huì)產(chǎn)生破壞效應(yīng)，所以工作完畢要及時(shí)拆除接地線。 (2)掛接地線前必須先驗(yàn)電，未驗(yàn)電掛接地線是基層中較普遍的習(xí)慣性違章行為，在懸掛時(shí)接地線道體不能和身體接觸。其工作原理采用基準(zhǔn)電壓比較式。 　　(7)接地電阻：接地體或自然接地體的對(duì)地電阻的總和，成為接地裝置的接地電阻，其數(shù)值等于接地裝置對(duì)地電壓與通過接地體流入地中電流的比值。我剛上班時(shí)工廠里有一臺(tái)1000噸的薩克米壓磚機(jī)，因?yàn)槠渌O(shè)備和數(shù)字地的原因?qū)е缕潆娮釉O(shè)施幾次燒毀，最后意大利派過來的技師（才畢業(yè)的中專生）更換設(shè)備后，指揮人在就地挖了個(gè)坑，埋了一根接地銅管和接地填料，搞成了單獨(dú)接地。接地方法：將每個(gè)設(shè)備的接地端子單獨(dú)接到接地裝置上。防雷接地是地面通信臺(tái)站安裝驗(yàn)收規(guī)范中最基本的安全要求，PLC的接地屬于低壓電器設(shè)備的2單點(diǎn)接地方式低壓電器設(shè)備的單點(diǎn)接地方式可分為：串聯(lián)式單點(diǎn)接地、并聯(lián)式單點(diǎn)接地、多分支單點(diǎn)接地。共用接地系統(tǒng)通常利用建筑物的基礎(chǔ)做接地極，其接地電阻一般在1歐姆以下，如有設(shè)備對(duì)接地電阻的要求更低，應(yīng)取其最小值。因此，沒有合理而良好的接地裝置是不能可靠地避雷的。 is connected by double lapped c