一点接地多点接地 IEEE142

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电气接地方式

TN-S TN-C TN-C-S TT IT接地系统得接线图解TN-S接地系统（整个系统得中性线与保护线就是分开得）TN-C接地系统（整个系统得中性线与保护线就是合一得）TT接地系统（TT接地系统有一个直接接地点，电气装置外露可导电部分则就是接地）TN-C-S接地系统（整个系统有一部分得中性线与保护线就是合一得）IT接地系统（IT接地系统得带电部分与大地间不直接连接，而电气装置得外露可导电部分则就是接地得）字母标识第一字母表示电力系统得对地关系T-----一点接地I-----所有带电部分与地绝缘，或一点经阻抗接地第二字母表示装饰得外露可导电部分对地关系T-----外露可导电部分对地直接电气连接，与电力系统得任何接地点无关N-----外露可导电部分与电力系统得接地点直接电气连接（在交流系统中，接地点通常就就是中性点）如果后面还有字母，这个字母表示中性线与保护线得组合S-----中性线与保护线就是分开得C-----中性线与保护线就是合一得（PEN线）简单说来,TN-C就就是把工作0线与保护接地共用,TN-S就就是把工作得0线与保护接地分开各使用一条线路、这两种供电系统都有各自得规范与要求、所以我们国家得配电系统中,使用后一种得情况即TN-S得更多一些、下面就是详略得资料，有时间您可以慢慢瞧：如何区别：TN-C系统、TN-S系统、TN-C-S系统、TT系统建筑工程供电使用得基本供电系统有三相三线制三相四线制等，但这些名词术语内涵不就是十分严格。

国际电工委员会（IEC ）对此作了统一规定，称为TT 系统、TN 系统、IT 系统。

其中TN 系统又分为TN-C 、TN-S 、TN-C-S 系统。

下面内容就就是对各种供电系统做一个扼要得介绍。

TT 系统TN-C供电系统→ TN 系统→ TN-SIT 系统TN-C-S（一）工程供电得基本方式根据IEC 规定得各种保护方式、术语概念，低压配电系统按接地方式得不同分为三类，即TT 、TN 与IT 系统，分述如下。

详解电路设计中的单点接地-多点接地-混合接地

详解电路设计中的单点接地/多点接地/混合接地
地线也是有阻抗的，电流流过地线时，会产生电压，此为噪声电压，而噪声电压则是影响系统稳定的干扰源之一，不可取。

所以，要降低地线噪声的前提是降低地线的阻抗。

众所周知，地线是电流返回源的通路。

随着大规模集成电路和高频电路的广泛应用，低阻抗的地线设计在电路中显得尤为重要。

这里就简单列举几种常用的接地方法：
单点接地
单点接地，顾名思义，就是把电路中所有回路都接到一个单一的，相同的参考电位点上。

如下所以，在实际应用时，可以采用串联和并联混合的单点接地方式。

在画PCB 板时，把互相不易干扰的电路放一层，把互相容易发生干扰的电路放不同层，再把不同层的地并联接地。

如下多点接地
当电路工作频率较高时，想象一下高频信号在沿着地线传播时，所到之处影响周边电路会有多么严重，因此所有电路就要就近接到地上，地线要求最短，多点接地就产生了。

多点接地，其目的是为了降低地线的阻抗，在高频(f 一定的条件下)电路中，要降低阻抗，主要从两个方面去考虑，一是减小地线电阻，二是减小地线感抗。

1，减小地线导体电阻，从电阻与横截面的关系公式中我们知道，要增加地线导通的横截面积。

但是在高频环境中，存在一种高频电流的趋肤效应(也叫集肤效应)，高频电流会在导体表面通过，所以单纯增大地线导体的横截面积往往作用不大。

可以考虑在导体表面镀银，因为银的导电性较其他导电物质优秀，故而会降低导体电阻。

单点接地和多点接地

接地有多种方式，有单点接地，多点接地以及混合类型的接地。

而单点接地又分为串联单点接地和并联单点接地。

一般来说，单点接地用于简单电路，不同功能模块之间接地区分，以及低频（f<1MHz）电子线路。

当设计高频（f>10MHz）电路时就要采用多点接地了或者多层板（完整的地平面层）。

对于一个电子信号来说，它需要寻找一条最低阻抗的电流回流到地的途径，所以如何处理这个信号回流就变得非常的关键。

第一，根据公式可以知道，辐射强度是和回路面积成正比的，就是说回流需要走的路径越长，形成的环越大，它对外辐射的干扰也越大，所以，PCB布板的时候要尽可能减小电源回路和信号回路面积。

第二，对于一个高速信号来说，提供有好的信号回流可以保证它的信号质量，这是因为PCB 上传输线的特性阻抗一般是以地层（或电源层）为参考来计算的，如果高速线附近有连续的地平面，这样这条线的阻抗就能保持连续，如果有段线附近没有了地参考，这样阻抗就会发生变化，不连续的阻抗从而会影响到信号的完整性。

所以，布线的时候要把高速线分配到靠近地平面的层，或者高速线旁边并行走一两条地线，起到屏蔽和就近提供回流的功能。

第三，为什么说布线的时候尽量不要跨电源分割，这也是因为信号跨越了不同电源层后，它的回流途径就会很长了，容易受到干扰。

当然，不是严格要求不能跨越电源分割，对于低速的信号是可以的，因为产生的干扰相比信号可以不予关心。

对于高速信号就要认真检查，尽量不要跨越，可以通过调整电源部分的走线。

（这是针对多层板多个电源供应情况说的）模拟信号和数字信号都要回流到地，因为数字信号变化速度快，从而在数字地上引起的噪声就会很大，而模拟信号是需要一个干净的地参考工作的。

如果模拟地和数字地混在一起，噪声就会影响到模拟信号。

一般来说，模拟地和数字地要分开处理，然后通过细的走线连在一起，或者单点接在一起。

总的思想是尽量阻隔数字地上的噪声窜到模拟地上。

当然这也不是非常严格的要求模拟地和数字地必须分开，如果模拟部分附近的数字地还是很干净的话可以合在一起。

单点接地和多点接地详解(Single point grounding and multipoint grounding)

单点接地和多点接地详解（Single point grounding andmultipoint grounding）Single point earthing multi point earthingThe problem to be solved in a single point is the "public ground impedance coupling" and the "low-frequency loop"",More often than not, it is aimed at "common mode interference" caused by long running linesIn low frequency circuits, the operating frequency of the signal is less than 1MHz, and its wiring and inductance between the devices are less affected, and the circulation caused by the grounding circuit has a greater impact on interference, so it should adopt one point grounding.When the signal operating frequency is greater than 10MHz, the ground impedance becomes very large. At this point, the ground impedance should be reduced as far as possible, and the ground multipoint grounding should be adopted.When the working frequency is between 1 and 10MHz, if one point grounding is adopted, the ground wire length shall not exceed 1/20 of the wavelength, or multipoint grounding method shall be adopted.Single point earthing between digital and analog ground, multipoint connection within digital ground.Ground wire interference and ground wire designGround design is a problem that people pay attention to in EMC design, but they don't know how to do it. After understanding the mechanism of the interference caused by ground wire, there is a definite idea in the design and implementation of ground wire. This issue begins with the introduction of the principle of interference caused by ground wire, enabling readers to understand the key and principles of designing ground wire. 1 what is the earth wire?There are two kinds of ground wire: safety and signal. The former is to ensure personal safety and equipment safety and set the ground wire, the latter is to ensure that the circuit works correctly set the ground wire. The main reason for the circuit interference is the signal ground, so the problem of signal ground is only discussed here.The general definition of the signal field is the potential reference point of the circuit.More appropriately, this definition is a hypothesis in our design of circuits. From this definition it is impossible to analyze and understand some ground interference problems. From now on, we will use the following definition when we analyze electromagnetic compatibility problems.The ground line is the ground impedance path of the signal current flowing back to the signal source.Since the ground wire is a path of the current, then there is a voltage on the ground line according to Ohm's law; since theearth is on a voltage, the earth line is not a equipotential body. In this way, when we design the circuit, the hypothesis about the potential of the ground wire is no longer established, so there are various errors in the circuit. This is the essence of ground interference.How big is the impedance of the 2 wire?An incomprehensible problem is that when we design the ground wire, the resistance of the ground wire is very small, then the potential difference on the ground will be large enough to cause the level of circuit errors. To understand the problem, understand the composition of ground impedance.The ground impedance of Z by the resistance and inductance part is composed of two parts, namely: Z = RAC + L J.Resistance component: the resistance of the conductor is divided into DC resistance RDC and AC resistance RAC. For AC current, because of the skin effect, the current is concentrated on the surface of the conductor, resulting in the decrease of the actual current cross section, the increase of resistance, and the relationship between the DC resistance and the AC resistance:RAC= 0.076rf1/2RDCType 1: the radius of the r= wire, the unit cm, the current frequency of the f= flowing through the wire, the unit Hz, the direct resistance of the RDC= wire, the unit omega.Inductance: any conductor has an internal inductance (which is distinguished from the usual external inductance,The outer inductance is a function of the area enclosed by the conductor, and the inductance is independent of the area enclosed by the conductor. For round sections, conductors are as follows:L=0.2S[ln (4.5/d) -1] (H)Type S= conductor length (m), d= conductor diameter (m)Table 1 illustrates the great difference between the DC and AC impedances. The impedance of very low frequencies can be considered to be the resistance of a conductor, can be seen from the table, with the increase of frequency, the impedance increases quickly when the frequency is above 100MHz, there are dozens of diameter 6.5mm ohm impedance of the wire length is only 10cm.Interference of 3 loop road and CountermeasuresLoop interference is a common interference that occurs between devices that are longer apart by longer cables. The intrinsic reason is the ground potential difference between the equipment. Ground voltage leads to the earth loop current. Due to the unbalanced circuit, the earth loop current leads to differential mode interference voltage that affects the circuit (Figure 1).The interference is caused by ground loop current, so inpractice, sometimes, when the ground wire of a device is disconnected, the interference phenomenon disappears, this is because the ground is broken, cut off the ground loop. This kind of phenomenon often occurs in the case of low interference frequency. When the interference frequency is high, the short open wire is not very important.Ground loop interference is the cause of 1: the ground potential of the two devices is different, forming the ground voltage. Under the driving of this voltage, there is a current flow between the loop formed by the equipment 1- interconnecting cable - equipment 2- ground. Because of the unbalance of the circuit, the current on each wire is different, so the differential mode voltage will be generated, which will cause interference to the circuit. The voltage on the ground wire is due to the larger power of the equipment, but also with this piece of ground wire, in the ground wire caused by a strong current, and the ground wire and a larger impedance produced.Reasons for the formation of ground loop interference 2: because of the Internet equipment in a strong electromagnetic field, the electromagnetic field in the "1 - internet cable equipment - Equipment - loop 2" in the formation of the induction loop, and 1 reasons like processes lead to interference.The solution to loop interference: basic ideas to solve the earth loop interference there are three: one is to reduce the grounding impedance, thereby reducing the interference voltage, but this leads to second reasons for the loop has no effect. The other is to increase the impedance of the earth loop,thereby reducing the ground loop current. When the impedance is infinite, the ground loop is actually cut, that is, the earth loop is eliminated. For example, it is a direct way to float one end of the device, or to disconnect the circuit board from the case. But due to electrostatic protection or safety considerations, such direct methods are often not allowed in practice. A more practical approach is the use of isolated transformers, optocoupler devices, common mode chokes, balanced circuits, and other methods. The third method is to change the grounding structure, connect the ground of one case to another, and connect it to the ground through another. This is the concept of single point grounding.4 common impedance coupling and countermeasureWhen the ground current of the two circuits flows through a common impedance, a common impedance coupling occurs, as shown in Figure 2 (a).The ground potential of a circuit will be affected by the working state of another circuit,That is, the ground potential of one circuit is modulated by the ground current of another circuit, and the signal of the other circuit is coupled into the previous circuit.Ground coupled amplifier intervalve: Figure 2 (a) of the amplifier, because the preamplifier circuit and power amplification circuit share a section of ground wire, power amplifier circuit grounding current is large, resulting in a ground voltage V is larger in the ground. This voltage isexactly in the input circuit of the preamplifier circuit. If a certain phase relation is satisfied, positive feedback is formed, resulting in the amplifier self excitation.Solution: there are two solutions, one is the power position change, make it close to the power amplification circuit, so that there will be no great falls on the ground voltage input circuit of preamplifier circuit in Figure 2 (b), as shown in. Another method is that the power amplification circuit is connected to the power supply by a ground wire alone, which is actually changed into a single point parallel grounding structure, as shown in Figure 2 (D).5 grounding strategyThe signals are shown in Figure 3 in several ways.Single point grounding: the ground wire of all circuits is connected to the same point of common ground wire, and can be further divided into series single point grounding and parallel single point grounding. The biggest advantage is that there is no ring road, relatively simple. But the ground wire is often too long, resulting in excessive impedance of the ground wire.Multipoint earthing: all the ground wire of the circuit is close to the ground, and the ground wire is very short, suitable for high frequency grounding. The problem is the existence of the loop.Mixed grounding: the grounding system uses inductance and capacitance to connect, and uses inductance and capacitancedevices to have different impedance characteristics at different frequencies, so that the ground system has different grounding structures at different frequencies.The problem of common impedance coupling caused by series single point grounding is solved by parallel single point grounding. However, parallel single point grounding is often not feasible because of excessive ground wire. Therefore, the scheme is flexible, the circuit according to the signal characteristics of each packet, will not interfere with the circuit in a group, a group within the circuit using a series of single point grounding, different groups of circuits using parallel single point grounding. As shown in figure 4. In this way, the problem of common impedance coupling is solved, and the problem of excessive ground wire is avoided.There are many ways of grounding, and the specific way of using that depends on the structure and function of the system. The concept of grounding was first used in the design and development of telephones. From the beginning of 1881, the single cable was used as the signal channel, and the earth as the common circuit. This is the first grounding problem. But using earth as a signal loop can cause excessive noise and atmospheric interference in the earth's circuit. In order to solve this problem, the signal return route is increased. Many grounding methods now exist are derived from successful experiences of the past, and these methods include:1) single point grounding: as shown in Fig. 1, single point grounding is a method of providing common potential reference points for many circuits together, so that signals can betransmitted between different circuits. If there is no public reference point, an error signal is sent. Single point grounding requires each circuit to be earthed only once and connected to the same point. This point is often referenced by the earth. Since there is only one point of reference, it is possible to believe that there is no earth loop, and hence there is no interference.2) multipoint grounding: as shown in Figure 2, as can be seen from the diagram, the circuit in the equipment is the reference point of the casing, and the shell of each device is referenced by the ground. The grounding structure can provide a low ground impedance, because each ground wire can be very short when multipoint grounding; and the plurality of wires are connected in parallel to reduce the total inductance of the grounding conductor. In high frequency circuits, multipoint grounding must be used, and the length of each ground wire is required to be less than the 1/20 of the signal wavelength.3) hybrid grounding: hybrid grounding includes both single point grounding characteristics and multi point grounding characteristics. For example, the power supply in the system requires single point grounding, and the radio frequency signal requires multipoint grounding, so that the hybrid grounding shown in Fig. 3 can be used. For DC, the capacitor is open circuit, the circuit is single point grounding, for radio frequency, the capacitor is connected, the circuit is multipoint grounding.When many connected devices (large physical size equipment and connecting cables and any interference signals are largecompared to the wavelength), there is possibility of interference through the chassis and cable function. When this happens, the path of the interference current is usually present in the system ground loop.When considering the grounding problem, two aspects should be considered, one is the self compatibility of the system, the other is the coupling of the external disturbance into the earth loop, which leads to the wrong work of the system. Because external disturbances are often random, it is often harder to solve them.Grounding requirementThere are many reasons for grounding, and several are listed below:1) safety grounding: the equipment that uses alternating current must be earthed by yellow green grounding, otherwise, when the insulation resistance between the power source and the casing is changed, it will cause electric shock damage.2) lightning grounding: the lightning protection system of the equipment is an independent system composed of lightning rod, lower conductor and the joint connected with the grounding system. The grounding system is usually shared with the ground reference for the power reference and the yellow green safety ground wire. Lightning discharge grounding only for facilities, the equipment does not have this requirement.3) EMC ground: grounding for electromagnetic compatibilitydesign, including:*: in order to prevent the shielding and grounding circuit between the parasitic capacitors due to existence of mutual interference, radiation field or on the outside electric circuit must be sensitive, isolation and shielding necessary, the isolation and shielding of the metal must be grounded.* filter grounding: the filter usually contains the signal line or the power line to the ground bypass capacitor, when the filter is not grounded, these capacitors are in suspension state, can not play the role of bypass.* noise and interference suppression: the control of internal noise and external interference requires many points on the equipment or system to be connected to the ground, thus providing a minimum impedance channel for interfering signals.* circuit reference: if the signal between the circuits is to be properly transmitted, a common potential reference point must be provided. This common potential reference point is the ground. Therefore, all interconnected circuits must be grounded.All of the above reasons form a comprehensive grounding requirement. However, the requirements for safety and lightning protection grounding are generally specified only when the design requirements are met,Others are implicit in the user's electromagnetic compatibility requirements for systems or equipment.Return directory3 grounding technology applicationsThe grounding technology and method used at present can be regarded as the experience summary of solving problems in the past. Typical grounding requirements are often limited to what is known as "single point grounding".The specific requirements of the docking site are not specifically proposed at the level of the circuit, as it is inappropriate to present specific requirements at this level. For digital circuits, most logic chips operate in a single ended circuit. That is to say, the potential of all signals is based on the power loop, and the potential is 0V. In analog circuits, the situation is similar. When the distance between the components is very close, it is easy to complete the generation, processing and shaping of the logic signal, but it will cause problems if the transmission line is too long or the reference point potential is not correct. We want to establish the concept that grounding is not required for every part or every system, for example, a single block circuit board does not have to be earthed to work properly. Grounding is necessary when data is being transmitted between devicesSeven 、 earthingThe safety of grounding grounding, grounding, here it is the work of grounding, grounding design is to minimize the coupling interference between the current of each branch, the mainmethods are: single point grounding, grounding, grounding plane series. In electronic equipment, grounding is an important way to control interference. If grounding and shielding can be correctly combined, most interference problems can be solved. In electronic equipment, the ground wire structure is roughly systematic, enclosure (shielded), digital (logical) and analog. In ground design, we should pay attention to the following points:1. correct selection of single point grounding and grounding point in low frequency circuit, the working frequency of the signal is less than 1MHz, the influence of inductance wiring and the smaller devices, and the grounding circuit formed by circulation on the interference influence, which should be used for grounding point. When the signal operating frequency is greater than 10MHz, the ground impedance becomes very large. At this point, the ground impedance should be reduced as far as possible, and the ground multipoint grounding should be adopted. The high frequency circuit should adopt multi-point series grounding, the ground wire should be short and leased, and the high frequency components shall be covered with grid like large area foil as far as possible. When the working frequency is between 1 and 10MHz, if one point grounding is adopted, the ground wire length shall not exceed 1/20 of the wavelength, or multipoint grounding method shall be adopted.2. separate analog and digital circuit circuit board both high-speed logic circuit, and a linear circuit, so they should try to separate them, and do not ground phase, ground wire and connected to the power supply end respectively. The grounding area of the linear circuit should be increased as much aspossible.3., as far as possible thickening of the grounding wire, if the ground wire is very thin, the grounding potential changes with the current, resulting in the electronic device timing signal level instability, noise performance deterioration. Therefore, the ground wire should be thickened as far as possible.4., the grounding wire constitutes a closed loop design, only by the digital circuit of the printed circuit board ground system, the grounding wire as a closed loop, can significantly improve the noise immunity. The reason is that there are a lot of integrated circuit components on printed circuit boards, especially when there are many power consuming components, because they are limited by the thickness of the grounding wire,If the grounding structure is loop, the potential difference will be reduced and the anti noise capability of electronic equipment will be improved.The two basic principles of electromagnetic compatibility (EMC): the first principle is to minimize the area of the current loop; the second principle is that the system uses only one reference plane.Of all the EMC problems, the main problem is caused by improper grounding. There are three signal grounding methods: single point, multipoint, and hybrid. When the frequency is lower than 1MHz, a single point grounding method can be adopted, but not suitable for high frequency. In high frequency applications, multipoint grounding is best adopted. Hybrid grounding is amethod of low frequency single point grounding and high frequency multipoint grounding. Ground layout is critical. The ground loop of high frequency digital circuits and low-level analog circuits must not be mixed.When designing a high frequency (f>10MHz) circuit, multipoint grounding or multilayer (complete ground level) is required.Analog signals and digital signals must be returned to the ground, because the digital signal changes rapidly, so that the noise caused by the digital ground will be very large, and analog signals need a clean reference work. If the analog and digital mix together, the noise will affect the analog signal. In general, analog and digital are to be separately handled and then joined together by fine wire or single point together. The general idea is to try to block the noise from the digital ground to simulate the ground. Of course, this is not a very strict requirement. Analog and digital must be separated. If the numbers near the analog part are still very clean, they can be put together.For general devices, the nearest ground is the best, the design has a complete multilayer plane, for grounding signal is very easy, the basic principle is to ensure the continuity of the line, reduce the number of vias; close to the ground plane or power plane, etc..Shielded cables have received interface board instead of signal, this is because there are a variety of noise signal on the ground, if the shield received signal, noise voltage will drive the common mode current along the interference shielding layeroutside, so the cable design is not good is generally the maximum noise output the source of electromagnetic interference. The premise, of course, is that the interface must be very clean.Ground wire zero lineThe first use of electricity and household electric power for electricity.Power is often said that the 380 volts of electricity, used for the factory. This is a three-phase four wire line in four. Three FireWire, a zero line. Three FireWire after load such as electric motors and other electrical equipment after the zero line to form a loop, the equipment can work normally. The zero line in power plant is grounded.Household electric means we often say 220 volts of electricity is also called single-phase electric, two wires, a live wire, a zero line. After fire loads such as light bulbs and other electric appliances after the zero line to form a loop, the use of electrical appliances to work properly. The zero line here in the power plant is grounded.Electric power and household electric zero line is grounded in a power plant, but we usually say the ground wire and the zero line is not a concept. You look at the three hole power socket in our house, if it is a formal construction, where a hole is a hole line, Shiling line, a hole is ground.Here the ground wire, the entire building after the collectionof ground. This is often said that the ground wire. Most household appliances are required to ground wire, that is, and the ground wire together2, FireWire ground wire zero lineThe first use of electricity and household electric power for electricity.Power is often said that the 380 volts of electricity, used for the factory. This is a three-phase four wire line in four. Three FireWire, a zero line. Three FireWire after load such as electric motors and other electrical equipment after the zero line to form a loop, the equipment can work normally. The zero line in power plant is grounded.Household electric means we often say 220 volts of electricity is also called single-phase electric, two wires, a live wire, a zero line. After fire loads such as light bulbs and other electric appliances after the zero line to form a loop, the use of electrical appliances to work properly. The zero line here in the power plant is grounded.Electric power and household electric zero line is grounded in a power plant, but we usually say the ground wire and the zero line is not a concept. You look at the three hole power socket in our house, if it is a formal construction, where a hole is a hole line, Shiling line, a hole is here the ground wire. The whole building after gathering ground. This is only the ground often said. Most household appliances are required to ground, and the ground wire is to connect together.Only one A/D can be grounded at one point, not more than two analog and digital.It is suggested that the mixed signal circuit board be split digitally and analog so that digital and analog isolation can be achieved. Although this method is feasible, there are many potential problems, especially in complex large-scale systems. The key problem is that the wiring can not be broken across the gap gap, and the electromagnetic radiation and signal crosstalk will increase dramatically once the wiring is broken across the gap gap. In PCB design, the most common problem is that the signal line crosses the partition or the power source to create the EMI problem.。

电气设备接地的规范要求

电气设备接地的规范要求电气设备接地是一项确保电气系统安全运行的重要措施。

在电气安全方面，接地是一项基本规范要求。

本文将介绍电气设备接地的规范要求，包括接地原理、接地形式、接地电阻要求以及接地系统的设计。

一、接地原理电气设备接地的原理是为了确保人身安全，防止电击事故的发生。

通过将电气设备与地进行连接，可以将设备的故障电流引入地下，从而消除电气设备的潜在危险。

二、接地形式根据电气设备的不同类型和用途，接地形式也有所不同。

常见的接地形式包括单点接地、多点接地和等电位接地。

1. 单点接地单点接地是将电气设备的中性点与地进行连接，通常用于低压配电系统。

单点接地的好处是易于实施和维护，但在发生线间短路时可能导致设备受损。

2. 多点接地多点接地是将电气系统的多个设备进行接地，可以避免单点接地时设备受损的问题。

多点接地适用于中压配电系统，其接地电阻要求较低。

3. 等电位接地等电位接地是在电气系统中同时接地多个设备，使得这些设备的接地电势相同。

等电位接地主要用于高压电力系统和对地电位要求较高的场所，能够有效地防止设备之间的电位差。

三、接地电阻要求为了确保电气设备接地系统的工作可靠，国家标准对接地电阻有一定的要求。

常见的接地电阻要求为：1. 低压配电系统：接地电阻小于4Ω；2. 中压配电系统：接地电阻小于1Ω；3. 高压电力系统：接地电阻小于0.5Ω。

接地电阻的测量应采用合适的仪器，并确保测量结果准确可靠。

四、接地系统的设计电气设备接地系统的设计涉及到接地电极的布置、导体截面的选择等方面。

在设计时，应考虑以下因素：1. 接地电极：接地电极的选择应根据实际情况进行，地下接地电极应埋入湿度较高的土壤中，以提高接地效果。

2. 导体截面：导体截面的选择应满足电流负荷的要求，并考虑导体的热稳定性和电气性能。

3. 接地回路：接地回路应设计为可靠的闭合回路，以确保故障电流能够顺利通过。

4. 设备保护：接地系统还应与设备的保护系统进行配合，确保在短路和过载等故障情况下能够及时切断电流。

ETCR2000钳形接地电阻测试仪使用说明书

ETCR2000钳型接地电阻测试仪使用说明书尊敬的顾客感谢您购买本公司ETCR2000钳型接地电阻测试仪。

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关于电缆屏蔽一点接地与两点接地的分析

关于电缆屏蔽一点接地与两点接地的分析《电力装置的继电保护和自动化装置设计规范》（GB50062-92）第条规定，当采用静态保护时，"采用屏蔽电缆，屏蔽层宜在两端接地。

"这与热工自动化专业规定屏蔽层一点接地不一致。

理论上讲，屏蔽层多点接地（注意，这里所指多点接地的地是全厂接地网的地，而非当地的自然地），屏蔽层完全处于等电位，干扰将减至最小，但实际无法办到，因此电气后退为"宜"两端接地。

由于静态保护的现场设备相对集中这也易于实现。

热工自动化做一点接地规定有以下考虑：1、热工自动化设备比较分散，就地设备处的屏蔽层都要接到全厂公用地困难较大，反之，对于接地热电偶等，如将两端均接至现场地也一样困难。

2、两端接地时，虽因屏蔽层感应产生的电流是二个方向相反的电流，因此，干扰可减少。

但是，在沿线全部浮空的情况下，仅一端接地，感应干扰也不会很大，可以满足要求。

为降低电场和磁场的干扰，二次控制系统中广泛使用屏蔽电缆。

屏蔽电缆的屏蔽层如何接地一直是一个令人关注的问题，现在尚无统一规定，而是根据具体情况采用不同的实施方法。

电缆屏蔽层接地有两种方式：一点接地或两端接地。

众所周知，对于通过电容耦合的电场干扰，一点接地即可大大降低干扰电压，发挥屏蔽作用。

对于通过感应耦合的磁场干扰，一点接地不能起到屏蔽作用，只有两端都接地，外部干扰电流产生的磁场才能在屏蔽层中感应产生一个与外部干扰电流方向相反的电流，这个电流起到抵销降低干扰电流的作用，即屏蔽作用。

可是两端接地时，如果两端地电位不一致(在地网流过暂态电流时)，则将在屏蔽层中产生一个附加电流，这个电流将在屏蔽电缆中信号线产生干扰电压。

正是由于两点接地的这种“有利”和“有弊”之间的矛盾，须根据具体情况来确定是否采用。

对于以往大量应用的通过高压开关场的常规二次回路，如电流、电压回路及直流控制回路等，其控制电缆的屏蔽层一般采用两点接地，因为这些电缆通常是长距离电缆，高压开关场的电磁干扰很强烈，必须采用两点接地以降低电磁干扰。

单点接地和多点接地详解

接地的方法很多，具体使用那一种方法取决于系统的结构和功能。“接地”的概念首次应用在电话的设计开发中。从1881年初开始采用单根电缆为信号通道，大地为公共回路。这就是第一个接地问题。但是用大地作为信号回路会导致地回路中的过量噪声和大气干扰。为了解决这个问题，增加了信号回路线。现在存在的许多接地方法都是来源于过去成功的经验，这些方法包括：
单点接地多点接地
单点地要解决的问题就是针对“公共地阻抗耦合”和“低频地环路”，
多点地是针对“高频所容易通过长地走线产生的共模干扰”.
低频电路中，信号的工作频率小于1MHz，它的布线和器件间的电感影响较小，而接地电路形成的环流对干扰影响较大，因而应采用一点接地。
当信号工作频率大于10MHz时，地线阻抗变得很大，此时应尽量降低地线阻抗，应采用就近多点接地。
电感成分：任何导体都有内电感（这区别于通常讲的外电感，外电感是导体所包围的面积的函数），内电感与导体所包围的面积无关。对于圆截面导体如下：
L=0.2S[ln(4.5/d) -1] （μH）
式中S=导体长度(m)，d=导体直径(m)
表1说明了直流电阻与交流阻抗的巨大差异。频率很低时的阻抗可以认为是导体的电阻，从表中可以看出，随着频率升高，阻抗增加很快，当频率达到100MHz以上时，直径6.5mm长度仅为10cm的导线也有数十欧姆的阻抗。
1．正确选择单点接地与多点接地在低频电路中，信号的工作频率小于1MHz，它的布线和器件间的电感影响较小，而接地电路形成的环流对干扰影响较大，因而应采用一点接地。当信号工作频率大于10MHz时，地线阻抗变得很大，此时应尽量降低地线阻抗，应采用就近多点接地。高频电路宜采用多点串联接地，地线应短而租，高频元件周围尽量用栅格状大面积地箔。当工作频率在1～10MHz时，如果采用一点接地，其地线长度不应超过波长的1/20，否则应采用多点接地法。

变压器铁芯多点接地故障处理

变压器铁芯多点接地故障处理变压器铁芯多点接地，是变压器较常见故障之一，查找和处理都有一定的难度。

常规的方法是吊罩检查，若直观上找不到故障点，一般用直流法或者交流法进行查找，不但工作量大、费用高、停电时间长给用户用电造成影响，而且大型变压器吊罩存在很大的风险。

下面介绍一种用电容器放电冲击法处理变压器铁芯多点接地的经过。

经过某变电所在预防性试验时，发现主变铁芯绝缘电阻严重降低（铁芯经小套管引至壳外接地），用兆欧表测量绝缘电阻读数有时为0，此时用万用表测量电阻为十几欧姆；有时在0～40MΩ之间摆动，同时听到变压器内部有轻微的放电声。

其它试验项目均正常（无色普仪，没做绝缘油色普分析）。

初步分析认为是残留杂物引起铁芯接地。

变压器基本情况此变压器投运前吊罩检查和试验无异常。

后因保护电源中断受到长达数分钟的6KV侧短路电流冲击，造成6KV三相套管烧坏，变压器油漏出着火，110KV A相套管闪络。

事后吊罩检查在变压器底部发现铜珠，测量线圈直流电阻、线圈绝缘电阻及铁芯对地绝缘电阻均无异常，更换套管后，各项试验均无问题。

初步处理此变电所始建于解放初期，几经扩建增容，使得变压器周围空间十分狭小HVDW3305地网接地电阻测试仪适用于测试各类接地装置的工频接地阻抗、接触电压、跨步电压、等工频特性参数以及土壤电阻率。

吊罩时需要运离现运行位置，这就意味着此变压器需要长时间停电，将直接影响煤矿的生产与安全，这是不允许的。

根据上述情况，决定放油后打开人孔检查并用高速油流冲洗铁芯。

打开人孔检查没发现问题，冲洗铁芯后测量铁芯对地绝缘为5000，恢复正常值。

注油后复测又变为0，将变压器投入运行带负荷测量铁芯对地电流为0.6A，说明这次处理没有效果，但进一步证实了是残留物引起的铁芯接地。

电容器放电冲击据有关资料介绍⑴，杂物悬浮引起的铁芯接地可用电容器放电冲击处理。

电容器瞬间放电产生的巨大电流将熔化或烧断残留杂物，或者电容器瞬间巨大冲击电流产生的电动力使残留杂物移开原来位置。

试述直流电桥式励磁回路一点接地保护基本原理及励磁回路两点接地保护基本原理

试述直流电桥式励磁回路一点接地保护基本原理及励磁回路两点接
地保护基本原理
直流电桥式励磁回路是一种常用的电力设备励磁回路，其保护基本原理可以分为一点接地保护和两点接地保护。

一点接地保护基本原理：在直流电桥式励磁回路的一点接地保护中，回路的负极接地，将回路的正极与地完全隔离。

当回路有异常时，如接地故障，电流会通过接地点流入地中，导致接地电流增大。

通过监测接地电流的大小，若接地电流超过设定值，就会触发保护装置，切断励磁回路，保护设备和人身安全。

两点接地保护基本原理：在直流电桥式励磁回路的两点接地保护中，回路的正极和负极均接地，形成一个闭环。

当回路有异常时，如接地故障，电流会从正极通过接地点流入地中，再从地中的另一接地点回到负极，形成一个环路。

通过监测回路两个接地点之间的电压差，若电压差超过设定值，就会触发保护装置，切断励磁回路，保护设备和人身安全。

两种接地保护方式的选择取决于具体的应用场景和电气设备的要求。

一点接地保护适用于对设备和人身安全要求较高的场合，能够及时发现并切断接地故障。

而两点接地保护适用于要求较高的电气设备，能够更加精确地检测接地故障的位置，减少故障引起的影响。

总之，直流电桥式励磁回路的一点接地保护和两点接地保护都是为了保护设备和人身安全而设计的，通过监测接地电流或回路电压差，一旦超过设定值就会触发保护装置，切断励磁回路。

不同的保护方式适用于不同的应用场景，能够有效预防和减少接地故障带来的风险。

弱电施工弱电系统的接地

弱电施工弱电零碎的接地之相礼和热创作A．一样平常规定1．弱电零碎的接地，按用处分有呵护性接地和功能性接地.呵护性接地分为：防电击接地、防雷接地、防静电接地和防电蚀接地；功能性接地分为：工作接地、逻辑接地、屏蔽接地和信号接地.分歧的接地有分歧的要求，应按计划决定的接地施工.2．必要接地的弱电零碎的接地安装应符合下列要求：（1）当配管采取镀锌电管时，除计划明白规定处，管子与管子、管子与金属盒子连接后不必跨接，但应服从下述规定：1）管子间采取螺纹连接时，管端螺纹长度不该小于管接头长度的1/2，螺纹概况应光滑、无锈蚀、缺损，在螺纹上应涂以电力复全脂或导电性防腐脂.连接后，其螺纹宜外露2~3扣.2）管子间采取带有紧定螺钉的套管连接时,螺钉应拧紧在振动的场合,紧定螺钉应有防松动措施.3）管子与盒子的连接不该采取塑料纳子，应采取导电的金属纳子.4）弱电管子内有PE线时，每只接线盒都应和PE线相连.（2）当配管采取镀锌电管，计划又规定管子间必要跨接时，应服从下述规定：1）明敷配管不该采取熔焊跨接，应采取计划指定的公用接上去线卡子跨接.2）埋地或埋设于混凝土中的电管，不该用线卡跨接，可采纳熔焊跨接.3）若管内穿有裸软PE铜线时，电管可不跨接.此PE 线必须与它所经过的每一只接线盒相连.（3）配管采取黑铁管时，若计划不要求跨接，则不必跨接.若要求跨接时，黑铁管之间及黑铁管与接线盒之间可采取圆钢跨接，单面焊接，跨接长度不宜小于跨接圆钢直径的6倍；黑铁管与镀锌桥架之间跨接时，应在黑铁管端部焊一只铜螺栓，用不小于4mm的铜导线与镀锌桥架相连.（4）当强弱电都采取PVC管时，为防止干扰，弱电配管应尽量防止与强电配管平行敷设，若必须平行敷设，相隔距离宜大于0.5m.（5）当强弱电用线槽敷设时，强弱电线槽宜分开；当必要敷设在同一线槽时，强弱电之间使用金属隔板隔开.B．电信设备的接地1．为防止外界电压危害人身安全和对设备的损害，抑制电气干扰，包管通讯设备正常工作，电信设备的以下部分均应接地：（1）直流电源、电信设备的机架、机壳；人站通讯电缆的金属护套和屏蔽层.（2）交流配电屏、整流器屏等供电设备的外露导电部分.（3）直流配电屏的外露部分.（4）交直流两用电信设备的机架、机框内与机架、机框不断缘的供电整流盘的外露导电部分.（5）电缆、架空线路及有关必要接地的部分，如放电器、避雷器、呵护间隙等.2．当低压配电零碎采纳TN制式供电，电信设备若要求严厉限定工频交流对其的干扰，且电信设备不容易做到与站内各种金黄色属构件尽缘时，应采取TN-S制式；当对干扰要求不太严厉时，可采取TN-C制式；当电信设备的走漏电流在10mA及以上时，应采取TN-S制式.3．配电屏、整流器屏等外露导电部分，当加固安装将其与机架、机框在电气上已连通时，仍需与PE线或PEN线相连.4．当采纳IT制式供电，电信设备的走漏电流在10mA 以上时，为了防止呵护设备误动作，可采纳双线圈变压器供电，其一次侧接入IT制式，二次侧若以TN制式供电，此时供电设备的接地与TN制式相反.5．电信设备的工作接地，一样平常要求单独设置，亦可与建筑物内变压器的工作接地共用一个接地安装.但必须经过尽缘的公用接地线与接地安装相连.6．电信设备采取共同接地安装时，其接地电阻应不大于1Ω，宜用两根截面积不小于25mm２的铜芯尽缘线穿管敷设到共同接地极上.当采取根底钢筋作为共同接极时，连接处应有铜铁过渡接头.C．电子设备的接地1．电子设备的信号接地、逻辑接地、功率接地、屏蔽接地和呵护接地等，一样平常合用一个接地极，其接地电阻不大于4Ω；当电子设备的接地与工频交流接地、防雷接地合用一个接地极时，其接地电阻不大于1Ω.屏蔽接地如单独设置，则其接地电阻一样平常为30Ω.2．对抗干扰才能差的电子设备，其接地应和防雷接地分开，两者互相距离宜在20m以上，对抗干扰才能较强的电子设备，两者距离可酌情减少，但不宜超出5m.当电子设备接地和防雷接地采取共同接地安装时，为了防止雷击时蒙受反击和包管设备的安全，应采取埋地铠装电缆供电.3．电缆屏蔽层必须接地，为防止发生干扰电流，对信号电缆和1MHZ及以下低频电缆应一点接地；对1MHZ以上电缆，为包管屏蔽层为地电位，应采纳多点接地.4．为了防止环路电流、瞬时电流的影响，辐射式接地零碎应采取一点接地；为消弭各接地点的电位差，防止彼此之间发生干扰，环式接地零碎应采取等电位连接；对混合式接地零碎，在电子设备外部采取辐射式接地，在电子设备外部采取环式接地零碎.5．接地环母线的截面，当电子设备频率在1MHZ以上时，用铜箔120mm×0.35mm；在1MHZ以下时，用铜箔mm×0.35mm.6．电子设备的接地极宜采取公开程度敷设，做成耙形或星形.D．数据处理设备的接地1．数据处理设备的接地电阻一样平常为4Ω，当与交流工频接地和防雷接地合用时，接地电阻为1Ω.2．对于走漏电流10mA以上的数据处理设备，其主机室内的金属体应互相连接成一体，连接线可采取6mm2的铜导线或25mm×4mm 镀锌扁钢，并进行接地，接地电阻不大于4Ω.3．为了减少趋肤效应和通道阻抗，直流工作接地的引下线应采远多芯铜导线，截面不宜小于35 mm2，当必要改善信号的工作条件时，宜采取多股铜绞线.4．直流工作接地与交流工作接地如不采取共同接地时，两者之间的电差不该超出0.5V，以免发生干扰.5．输出信号的电缆穿钢管敷设，或敷设在带金属盖板的金属桥架内，钢管及桥架均应接地.E．电声、电视零碎的接地1．电声、电视零碎的接地电阻一样平常为4Ω，工业电视零碎如设备容量≤0.5kV A时，接地电阻可不大于10Ω.2．架设在建筑物顶部的天线金属底座必须与建筑物顶部的避雷网相连，构成避雷零碎，经过至多在分歧方向的两根引下线或建筑物内的主钢筋进行接地.3．为防止由于接地电位差形成交流杂散波的干扰，闭路电视和工业电视必须采取一点接地.4．电视零碎的传输电缆穿金属管敷设时，金属管要接地，用以防止干扰.F．接地极和接地线的安装1．强弱电采取联合接地极时，接地电阻必须小于1Ω.2．采取联合接地极时，弱电接地引出线和强电接地引出线不克不及从同一点引出，两者要相距3m以上.3．对于抗干扰要求高的设备，例如电脑、消防操纵室的接地干线使用截面积不小于25 mm2尽缘铜导线两根或固定在尽缘子上的接地排，防止和强电接地线相通.。

弱电施工弱电系统的接地

弱电施工弱电系统的接地之公保含烟创作A．一般规则1．弱电系统的接地，按用途分有呵护性接地和功用性接地.呵护性接地分为：防电击接地、防雷接地、防静电接地和防电蚀接地；功用性接地分为：任务接地、逻辑接地、屏蔽接地和信号接地.分歧的接地有分歧的要求，应按设计决议的接地施工.2．需要接地的弱电系统的接地装置应契合下列要求：（1）当配管采用镀锌电管时，除设计明确规则处，管子与管子、管子与金属盒子衔接后不用跨接，但应遵守下述规则：1）管子间采用螺纹衔接时，管端螺纹长度不应小于管接头长度的1/2，螺纹概略应润滑、无锈蚀、缺损，在螺纹上应涂以电力复全脂或导电性防腐脂.衔接后，其螺纹宜外露2~3扣.2）管子间采用带有紧定螺钉的套管衔接时,螺钉应拧紧在振动的场所,紧定螺钉应有防松动办法.3）管子与盒子的衔接不应采用塑料纳子，应采用导电的金属纳子.4）弱电管子内有PE线时，每只接线盒都应和PE线相连.（2）当配管采用镀锌电管，设计又规则管子间需要跨接时，应遵守下述规则：1）明敷配管不应采用熔焊跨接，应采用设计指定的专用接下来线卡子跨接.2）埋地或埋设于混凝土中的电管，不应用线卡跨接，可采用熔焊跨接.3）若管内穿有裸软PE铜线时，电管可不跨接.此PE 线必需与它所经过的每一只接线盒相连.（3）配管采用黑铁管时，若设计不要求跨接，则不用跨接.若要求跨接时，黑铁管之间及黑铁管与接线盒之间可采用圆钢跨接，单面焊接，跨接长度不宜小于跨接圆钢直径的6倍；黑铁管与镀锌桥架之间跨接时，应在黑铁管端部焊一只铜螺栓，用不小于4mm的铜导线与镀锌桥架相连.（4）当强弱电都采用PVC管时，为避免搅扰，弱电配管应尽量避免与强电配管平行敷设，若必需平行敷设，相隔间隔宜年夜于0.5m.（5）当强弱电用线槽敷设时，强弱电线槽宜分开；当需要敷设在同一线槽时，强弱电之间应用金属隔板隔开.B．电信设备的接地1．为避免外界电压危害人身平安和对设备的损害，抑制电气搅扰，担保通信设备正常任务，电信设备的以下局部均应接地：（1）直流电源、电信设备的机架、机壳；人站通信电缆的金属护套和屏蔽层.（2）交流配电屏、整流器屏等供电设备的外露导电局部.（3）直流配电屏的外露局部.（4）交直流两用电信设备的机架、机框内与机架、机框不时缘的供电整流盘的外露导电局部.（5）电缆、架空线路及有关需要接地的局部，如放电器、避雷器、呵护间隙等.2．当高压配电系统采用TN制式供电，电信设备若要求严格限制工频交流对其的搅扰，且电信设备不容易做到与站内各种金黄色属构件绝缘时，应采用TN-S制式；当对搅扰要求不太严格时，可采用TN-C制式；当电信设备的泄漏电流在10mA及以上时，应采用TN-S制式.3．配电屏、整流器屏等外露导电局部，当加固装置将其与机架、机框在电气上已连通时，仍需与PE线或PEN线相连.4．当采用IT制式供电，电信设备的泄漏电流在10mA 以上时，为了避免呵护设备误举措，可采用双线圈变压器供电，其一次侧接入IT制式，二次侧若以TN制式供电，此时供电设备的接地与TN制式相同.5．电信设备的任务接地，一般要求独自设置，亦可与修建物内变压器的任务接地共用一个接地装置.但必需通过绝缘的专用接地线与接地装置相连.6．电信设备采用共同接地装置时，其接地电阻应不年夜于1Ω，宜用两根截面积不小于25mm２的铜芯绝缘线穿管敷设到共同接地极上.当采用根底钢筋作为共同接极时，衔接处应有铜铁过渡接头.C．电子设备的接地1．电子设备的信号接地、逻辑接地、功率接地、屏蔽接地和呵护接地等，一般合用一个接地极，其接地电阻不年夜于4Ω；当电子设备的接地与工频交流接地、防雷接地合用一个接地极时，其接地电阻不年夜于1Ω.屏蔽接地如独自设置，则其接地电阻一般为30Ω.2．对立搅扰能力差的电子设备，其接地应和防雷接地分开，两者相互间隔宜在20m以上，对立搅扰能力较强的电子设备，两者间隔可酌情增加，但不宜超越5m.当电子设备接地和防雷接地采用共同接地装置时，为了避免雷击时遭受还击和担保设备的平安，应采用埋地铠装电缆供电.3．电缆屏蔽层必需接地，为避免发作搅扰电流，对信号电缆和1MHZ及以下低频电缆应一点接地；对1MHZ以上电缆，为担保屏蔽层为地电位，应采用多点接地.4．为了避免环路电流、瞬时电流的影响，辐射式接地系统应采用一点接地；为消除各接所在的电位差，避免彼此之间发作搅扰，环式接地系统应采用等电位衔接；对混合式接地系统，在电子设备内部采用辐射式接地，在电子设备外部采用环式接地系统.5．接地环母线的截面，当电子设备频率在1MHZ以上时，用铜箔120mm×0.35mm；在1MHZ以下时，用铜箔mm×0.35mm.6．电子设备的接地极宜采用地下水平敷设，做成耙形或星形.D．数据处置设备的接地1．数据处置设备的接地电阻一般为4Ω，当与交流工频接地和防雷接地合用时，接地电阻为1Ω.2．关于泄漏电流10mA以上的数据处置设备，其主机室内的金属体应相互衔接成一体，衔接线可采用6mm2的铜导线或25mm×4mm 镀锌扁钢，并停止接地，接地电阻不年夜于4Ω.3．为了增加趋肤效应和通道阻抗，直流任务接地的引下线应采遥多芯铜导线，截面不宜小于35 mm2，当需要改善信号的任务条件时，宜采用多股铜绞线.4．直流任务接地与交流任务接地如不采用共同接地时，两者之间的电差不应超越0.5V，以免发作搅扰.5．输入信号的电缆穿钢管敷设，或敷设在带金属盖板的金属桥架内，钢管及桥架均应接地.E．电声、电视系统的接地1．电声、电视系统的接地电阻一般为4Ω，工业电视系统如设备容量≤0.5kVA时，接地电阻可不年夜于10Ω.2．架设在修建物顶部的天线金属底座必需与修建物顶部的避雷网相连，构成避雷系统，通过至少在分歧方向的两根引下线或修建物内的主钢筋停止接地.3．为避免由于接地电位差造成交流杂散波的搅扰，闭路电视和工业电视必需采用一点接地.4．电视系统的传输电缆穿金属管敷设时，金属管要接地，用以避免搅扰.F．接地极和接地线的装置1．强弱电采用结合接地极时，接地电阻必需小于1Ω.2．采用结合接地极时，弱电接地引出线和强电接地引出线不能从同一点引出，两者要相距3m以上.3．关于抗搅扰要求高的设备，例如电脑、消防控制室的接地支线应用截面积不小于25 mm2绝缘铜导线两根或固定在绝缘子上的接地排，避免和强电接地线相通.。

发电厂电力系统接地故障的判断与措施分析丁晓毅

发电厂电力系统接地故障的判断与措施分析丁晓毅发表时间：2017-06-13T11:29:53.293Z 来源：《电力设备》2017年第6期作者：丁晓毅[导读] 摘要：随着电网改造工程的逐步实施,配电线路供电方式也发生了一系列的改变。

传统的“两线一地”供电方式,被当前的中性点不接地“三相三线”所代替。

（河南省国家电投平顶山热电有限公司河南省 467000）摘要：随着电网改造工程的逐步实施,配电线路供电方式也发生了一系列的改变。

传统的“两线一地”供电方式,被当前的中性点不接地“三相三线”所代替。

改变供电输电方式后,带来三大优势:第一是配电线路的绝缘水平大幅度提高了;第二是配电线路的跳闸率大幅度降低了;第三是供电的稳定性增强,减少了线路的损耗。

这三点变化对于电网的运行意义重大,但是新的供电方式在实际的运营中,往往极易出现单相接地故障,这些故障在大风天、雨雪天等恶劣天气环境中的故障发生率更高,导致配电网和变电设备在安全经济运行方面受到了极大的影响。

本文着重对发电厂直流系统接地故障的判断与措施进行了简要的分析。

关键字：电力系统；接地故障；措施1引言在电力系统中，发电厂直流系统是非常重要的构成部分之一。

直流系统需发挥的功能包括面向继电保护装置、自动控制装置、事故信号、事故照明、主设备操作控制提供电源支持。

在整个系统正常运行的状态下，直流系统负极对地、正级对地均为绝缘状态。

若两者中的其中一点发生接地故障，但由于未形成完整回路，故直流系统的整体运行不会受到影响。

此时，若另一点同样出现接地故障，形成完整回路后就极易导致正极、负极金属短路事故，或造成继电器短接，对整个电力系统而言有非常不利的影响。

故而，从直流系统运行维护的实践上来看，在已发生一点接地故障后，必须根据故障的具体表现来快速查找故障发生点，并采取有效处理措施以消除接地故障对直流系统运行不良影响，确保其可靠性与稳定性。

2发电厂电力系统中常见的接地故障2.1两点接地故障相关研究表明，因电阻性单点接地而引发的接地电阻阻值不高问题，当其比预定的直流系统值还低时，就会出现明显的接地故障。

EMC中的两种接地技术

EMC中的两种接地技术郭亚红【摘要】电磁兼容接地设计有单点接地和多点接地2种基本方法，低频电路中要求用单点接地，高频电路中用多点接地，用多点接地设备如果不能通过EFT/B测试，可以尝试单点接地方法。

实验证明，对某些高频电路完全可以用单点接地方法满足EMC要求。

%The EMC grounding design consists of single-point grounding and multi-point grounding. Low-frequency circuits require single-point grounding, while multi-point grounding is usually used for equipments of high-frequency circuits. However, when the equipment can not pass the EFT/B test, single-point grounding can be used instead. Experiments prove that some high-frequency circuits can use single-point grounding to meet the EMC requirements.【期刊名称】《河北工业科技》【年(卷),期】2011(028)004【总页数】3页(P270-271,274)【关键词】接地技术；EMC；EFT/B【作者】郭亚红【作者单位】漯河职业技术学院，河南漯河462002【正文语种】中文【中图分类】TM15接地技术是一种成本最低、在EMC(电磁兼容)技术中比较可行的技术。

通常,应用良好的接地技术可以解决50%以上的EMC问题[1]。

当然接地技术本身是融入到屏蔽和滤波技术中的,因而它又是一种相对复杂的技术[2]。

在设计产品时,必须明确接地方法,而不能随意使用,可以在单点和多点接地技术这2种基本接地方法中任选一种。

一点接地 多点接地 IEEE142

电气接地方式

详解电路设计中的单点接地-多点接地-混合接地

单点接地和多点接地

单点接地和 多点接地详解(Single point grounding and multipoint grounding)

电气设备接地的规范要求

ETCR2000钳形接地电阻测试仪使用说明书

关于电缆屏蔽一点接地与两点接地的分析

单点接地和 多点接地详解

变压器铁芯多点接地故障处理

试述直流电桥式励磁回路一点接地保护基本原理及励磁回路两点接地保护基本原理

弱电施工弱电系统的接地

弱电施工弱电系统的接地

发电厂电力系统接地故障的判断与措施分析 丁晓毅

EMC中的两种接地技术

一点接地多点接地 IEEE142

单点接地和多点接地详解(Single point grounding and multipoint grounding)

单点接地和多点接地详解

发电厂电力系统接地故障的判断与措施分析丁晓毅