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1、現代建筑接地系統如何實現準確可靠運行 智能建筑設備的電器保護極為重要,為了保證智能建筑中電氣設備的安全可靠運行。TN-C系統也被稱之為三相四線系統,該系統中性線N與保護接地線PE合二為一,通稱PEN 線。這種接地系統雖對接地故障靈敏度高,線路經濟簡單,但它只適合用于三相負荷較平衡的場所。 Electrical protection equipment of intelligent building is very important, in order to ensure the safe and reliable operation of the electrical equipment i2、n intelligent building. The TN-C system is also known as the four phase three wire system, the neutral line of the system of N and protective ground wire become known as the PE, PEN line. The grounding system, grounding fault of high sensitivity, simple circuit economy, but it is only suitable for t3、hree-phase load is balanced place. 智能建筑中,除了部分風機等負荷為三相負荷外,其余設備一般均為單相負荷,在實際運行中難以實現三相負荷平衡,因此在PEN線中存在著不平衡電流;加上建筑內大量采用熒光燈、晶閘管等設備,導致其在供電線路中存在著高次諧波電流,在非故障情況下,諧波電流會在中性線N上疊加,使中性線N電壓波動,且電流時大時小極不穩定,造成中性 點接地電位不穩定漂移。 Intelligent building, in addition to some fan load of three-phase load, the other equipment in g4、eneral are single-phase load, difficult to realize three-phase load balance in the actual operation, so in the PEN line unbalance current; with the construction of the fluorescent lamp, such as thyristor devices, leads to the existence harmonic current in the power supply line, under fault condition5、s, the harmonic current will be superimposed on the neutral line N, the neutral line N voltage fluctuation, and the current size is very unstable, resulting in the neutral point grounding potential unstable drift. 不但會使設備外殼帶電,對人身造成不安全,而且也無法取到一個合適的電位基準點,精密電子設備無法準確可靠運行。由此可見TN-C系統不適合作為智能建筑的接地系統。 Not onl6、y will make the equipment shell charged, to human body caused by unsafe, but also unable to get to a suitable potential reference point, precision electronic equipment can not be accurate and reliable operation. It is concluded that the TN-C system is not suitable as a grounding system of intelligen7、t building. 為把雷電流迅速導入大地,以防止雷害為目的的接地叫作防雷接地。智能建筑內有大量的電子設備與布線系統,如通信自動化系統,火災報警及消防聯動控制系統,樓宇自動化系統,保安監控系統,辦公自動化系統,閉路電視系統等,以及他們相應的布線系統。建筑的各層頂板,底板,側墻,吊頂內幾乎被各種布線布滿。 As the lightning current quickly into the earth, for the purpose to prevent lightning grounding called lightning protection and grounding. In the8、 intelligent building electronic equipment and wiring systems, such as communication automation system, fire alarm and fire control systems, building automation systems, security monitoring systems, office automation systems, closed circuit television system, as well as their corresponding wiring sy9、stem. Each layer of building roof, floor, wall, the ceiling was covered with various wiring. 這些電子設備及布線系統一般均屬于耐壓等級低,防干擾要求高,最怕受到雷擊的部分,一旦受到雷擊會使電子設備受到不同程度的損壞或嚴重干擾。因此對智能建筑的防雷接地設計必須嚴密、可靠。 These electronic equipment and cabling system voltage levels are generally low, for high anti-interference, fear by th10、e lightning part, once struck by lightning can make the electronic equipment are subject to different degrees of damage or serious disturbance. Therefore, lightning protection grounding design of intelligent building must be tight, reliable. 智能建筑的所有功能接地,必須以防雷接地系統為基礎,并建立嚴密、完整的防雷結構。絕大多數情況下智能建筑應按照第二類或第11、三類防雷建筑物的防雷措施設計。 All functional earthing of intelligent building, must be based on the lightning protection and grounding system as the basis, and the establishment of lightning protection of tight structure, complete. Intelligent building in most cases should be in accordance with the design of ligh12、tning protection measures of second or third types of lightning protection of buildings. 電子設備的直流接地有單點接地、多點接地和浮地。單點接地是指整個電路系統中只有一個物理點被定義為接地參考點,其他各個需要接地的點都直接接到這一點上。多點接地是指電子設備中各個接地點都直接接到距它最近的接地平面上。 DC electronic equipment grounding with single-point grounding, multi-point grounding and floating. Single13、 point grounding refers to the whole circuit system is only a physical point is defined as the ground reference point, other all need grounding point directly to this point. Multipoint grounding refers to the electronic device each grounding are directly to the nearest the ground plane. 浮地是指設備地線系統在電14、氣上與大地相絕緣,以減少由于地電流引起的電磁干擾。智能建筑的接地系統不宜采用浮地,它必須有穩定的參考電位,若浮接則易受電磁場的雜訊干擾,使系統發生誤動作。 Floating refers to equipment grounding system is insulated to ground, so as to reduce the electromagnetic interference current caused by. Intelligent building grounding system should not use floating, it must have a refere15、nce potential stable, if floating is susceptible to noise interference of electromagnetic field, the system malfunction. 頻率低于1MHz時,電纜屏蔽層應采用單點接地方式,以防止其他電流流經電纜屏蔽層產生電磁干擾。因此,若采用同軸電纜傳輸信號時,如要通過屏蔽層提供信號回路,可 在信號源端將信號源與屏蔽層相連接地。也可以將屏蔽電纜穿入金屬管內或采用雙層屏蔽電纜,將金屬管或電纜外屏蔽層在兩端接地,而金屬管內的電纜屏蔽層或屏蔽電纜的內屏蔽層一端接地。 The frequency i16、s lower than 1MHz, cable shielding layer adopts the way of grounding point, to prevent other current electromagnetic interference through the cable shielding layer. Therefore, if the use of the coaxial cable transmission signal, such as to provide signal loop through the shielding layer, the signal 17、source connects the signal source and the shielding layer. Can also be shielded cable passes through the metal tube or adopts a double-layer shielding cable, metal tube or outside the cable shielding layer at both ends of the ground, and the metal pipe in the cable shield or shield cable shield grou18、nd at one end. 智能化樓宇的供電接地系統宜采用TN-S系統,按規范宜采用一個總的共同接地裝置,即統一接地體。統一接地體為接地電位基準點,由此分別引出各種功能接地引線,利用總等電位和輔助等電位的方式組成一個完整的統一接地系統。 Intelligent building power supply grounding system should adopt TN-S system, according to the specification should adopt a common earthing device, namely integrated grounding. Integrated grounding for the grounding potential reference point, which are respectively led out various functional earthing wire, using general equipotential and auxiliary equipotential way to form a complete unity of grounding system.