{"id":78912,"date":"2022-03-23T02:26:43","date_gmt":"2022-03-23T00:26:43","guid":{"rendered":"https:\/\/gahzly.com\/%d8%a3%d9%86%d8%b8%d9%85%d8%a9-%d8%a7%d9%84%d8%aa%d8%a3%d8%b1%d9%8a%d8%b6-%d8%a7%d9%84%d9%83%d9%87%d8%b1%d8%a8%d8%a7%d8%a6%d9%8a%d8%a9\/"},"modified":"2023-10-31T19:05:27","modified_gmt":"2023-10-31T17:05:27","slug":"electrical-grounding-systems","status":"publish","type":"post","link":"https:\/\/gahzly.com\/en\/\u0645\u0642\u0627\u0644\/electrical-grounding-systems\/","title":{"rendered":"Electrical grounding systems 2"},"content":{"rendered":"
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Electrical grounding systems<\/span><\/span><\/h2>\n<\/div>\n
<\/div>\n<\/header>\n
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Electrical grounding systems are a very wide field that includes the grounding of electric current generators, methods of grounding electrical transformers, grounding electronics to ensure that they are not subject to interference from the main grounding, as well as the relationship of grounding systems with various electrical protection devices. <\/span>Despite the breadth of this field, the literature usually presents it by explaining the methods of grounding the different transformers and connecting the grounding point of them to the loads. <\/span>The focus is on grounding systems, starting from the second end of the distribution transformer, because before this point from the primary end of the transformer to the electric generators, it is electrically isolated (but magnetically connected) from the secondary end of the distribution transformer, which makes it possible to overlook it to simplify the matter. <\/span>Also, the secondary end of the low-voltage distribution transformers is what eventually feeds the loads, which makes the relationship between the grounding of the loads and this transformer a close relationship.<\/span><\/span><\/p>\n

The field of electrical grounding systems is usually introduced by\u00a0 <\/span><\/span>IEC 60364<\/span><\/span><\/span> \u00a0and\u00a0 <\/span><\/span>IEEE 80\/81 standards<\/span><\/span><\/span> \u00a0and the resulting literature in the field. <\/span>Therefore, this article will start from the same base and give a brief introduction in this field through these two standards (without going too deep into\u00a0 <\/span><\/span>IEEE<\/span><\/span><\/span> standards) with multiple additions, the most important of which is the \u00a0famous <\/span>Schneider\u00a0 <\/span><\/span>Electrical Installation Guide .<\/span><\/span><\/span><\/p>\n

The purpose of electrical grounding systems can be summarized in two main points:<\/span><\/span><\/p>\n

A- Ground Protection:-<\/span><\/span><\/strong><\/p>\n

Connecting current-conducting surfaces, grounding points of sockets, etc. to earth protects us from exposure to electric\u00a0 <\/span><\/span>shock<\/span><\/span><\/span> \u00a0by making sure that the voltage of the conductive surfaces is kept equal to the earth’s voltage. <\/span>After the failure of the electrical insulation of any of the wires and their contact with any metal surface, the current will pass directly to the ground instead of passing through the body of any person touching that surface, or passing through any flammable material and causing a fire, or passing through devices that are not intended for such a high current. causing damage to it.<\/span><\/span><\/p>\n

B- Functional grounding:-<\/span><\/span><\/strong><\/p>\n

What is meant by functional grounding is the current-carrying grounding line returning to the current source, as is practiced in some of the grounding systems presented in this article. <\/span>One of the power transmission systems based on the return of current through the ground is the\u00a0 <\/span><\/span>Single-Wire Earth Return system<\/span><\/span><\/a><\/p>\n

A –\u00a0 <\/span><\/span>Basic requirements for grounding electrical systems:<\/span><\/span><\/strong><\/span><\/h2>\n

The parts of electrical grounding systems are defined as follows:<\/span><\/span><\/p>\n

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Illustration of the components of the grounding system according to the number shown in the picture:<\/span><\/span><\/figcaption><\/figure>\n<\/div>\n

1- (No. 1 in the picture above) \u2013 the\u00a0 <\/span><\/span>Earth Electrode<\/span><\/span><\/span> \u00a0, which is a single conductor (copper cable without insulation), or a group of conductors connected together and located underground (under the soil) with the possibility of\u00a0 <\/span><\/span>Rode<\/span><\/span><\/span> rods \u00a0planted in the ground and connected with the conductors To form a grounding network under the soil. <\/span>And the rods are planted in the ground at sufficient distances so that the maximum value of the current passing through one of them does not affect or raise the voltage of the rest. <\/span>The following picture provides a more detailed illustration of the shape of the grounding grid placed under the soil.<\/span><\/span><\/p>\n

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<\/figure>\n<\/div>\n

2- The Earthing\u00a0 <\/span><\/span>Conductor<\/span><\/span><\/span> \u00a0is a conductor (cable), or group of conductors, that connects the main grounding line (No. 6 in the image above) to the\u00a0 <\/span><\/span>Earth Electrodes<\/span><\/span><\/span> \u00a0(No. 1). <\/span>Its practical design looks as shown in the two pictures here:<\/span><\/span><\/p>\n

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<\/figure>\n<\/div>\n
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<\/figure>\n<\/div>\n

3 –\u00a0 <\/span><\/span>Protective Conductor<\/span><\/span><\/span> \u00a0or\u00a0 <\/span><\/span>Protective Earthing (PE)<\/span><\/span><\/span> \u00a0responsible for connecting all metal surfaces of electrical devices together in the facility and connecting them to the same main earthing line (No. 6). <\/span>An example of this protective conductor is the third line plug\/plug (often the longest and middle to the top) found in homes. <\/span>As well as ground lines for air conditioners and other loads connected to the body of the distribution board. <\/span>They are usually yellow and green.<\/span><\/span><\/p>\n

4 \u2013\u00a0 <\/span><\/span>Extraneous Conductive Part Defined<\/span><\/span><\/span> \u00a0by the British Standard\u00a0 <\/span><\/span>BS 7671<\/span><\/span><\/span> \u00a0as devices that meet the three conditions together:<\/span><\/span><\/p>\n

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  • 1- It must be made of a conductive material<\/span><\/span><\/li>\n
  • 2- It should be liable to bear the earth\u2019s effort (such as if its surface is in contact with the ground).<\/span><\/span><\/li>\n
  • 3- It shall not be part of any electrical system<\/span><\/span><\/li>\n<\/ul>\n

    As you can see from the definition, you do not need to ground every metal in your facility or home because the second requirement is that this metal is liable to carry an electric potential. <\/span>The reason for this condition is that if any of the live wires come into contact with the surface of any electrical device (such as the surface of a microwave oven, for example), then when a person touches the surface of the microwave on the one hand and the surface of any other metal object that carries the earth’s voltage on the other hand, the current will pass through his body, which is what should be banned. <\/span>From this rule, you can exclude all objects that cannot support the effort of the earth, such as door handles (for wooden doors), window frames, and others. <\/span>There is also another obvious condition that is not mentioned in the list above, which is accessibility and touchability of the device. <\/span>Therefore, you can exclude pipes buried underground or behind a wall from the list. <\/span>Metal surfaces covered with an electrical insulator such as plastic and others are also excluded.<\/span><\/span><\/p>\n

    From the same point of view, and based on the method of installing and connecting the various devices, it is possible to exclude pieces such as stair railings, metal tables, and others. <\/span>As a general rule, pieces with electrical resistance must be grounded to earth equal to or greater than the following:<\/span><\/span><\/p>\n

    R < Vo\/Ib<\/span><\/p>\n

    Where the voltage\u00a0 <\/span><\/span>Vo\u00a0<\/span><\/span><\/span> is the voltage of the electrical system in the facility ( <\/span><\/span>230V\u00a0<\/span><\/span><\/span> for example) and\u00a0 <\/span><\/span>Ib<\/span><\/span><\/span> \u00a0is the limit of current allowed without causing harm to humans ( <\/span><\/span>30mA\u00a0<\/span><\/span><\/span> according to\u00a0 <\/span><\/span>IEC<\/span><\/span><\/span> standards ). <\/span>As an example of\u00a0 <\/span><\/span>230V\u00a0<\/span><\/span><\/span> , any piece with a resistance higher than\u00a0 <\/span><\/span>230\/0.030 = 7.66OHM<\/span><\/span><\/span> \u00a0between it and the earth must be grounded with a separate cable.<\/span><\/span><\/p>\n

    5 –\u00a0 <\/span><\/span>Bonding Conductor<\/span><\/span><\/span> \u00a0, which aims to connect all metal parts together to ensure that no voltage difference forms between any of them and the ground, and creates what is known as\u00a0 <\/span><\/span>Equipotential Bonding<\/span><\/span><\/span> . <\/span>It is used to connect the different pieces that were explained in the previous point.<\/span><\/span><\/p>\n

    The linking of all metal pieces together is known as the\u00a0 <\/span><\/span>Equipotential Bonding\u00a0<\/span><\/span><\/span> system according to\u00a0 <\/span><\/span>IEC\u00a0<\/span><\/span><\/span> standards , and it was established with the aim that if any of the various metal surfaces in the facility (such as water or gas pipes) come into contact with any of the live electrical voltage lines, the voltage on all These surfaces will be equal (because it will become like a single metallic body without any electrical resistance between its parts), so no current discharge will occur anywhere else to save the lives of people and devices until the protection devices catch the error and separate the circuit.<\/span><\/span><\/p>\n

    6 – The main earthing\u00a0 <\/span><\/span>terminal<\/span><\/span><\/span> \u00a0, which is\u00a0 the <\/span><\/span>bar\u00a0<\/span><\/span><\/span> or the metal tape to which all the grounding points in the facility are connected from the connection connections (No. 5) and protection conductors (No. 3) as explained in the previous points. <\/span>It is usually located inside the\u00a0 <\/span><\/span>Distribution Boards <\/span><\/span><\/span>\u00a0(as the following picture)\u00a0<\/span><\/span><\/span> , or\u00a0 the <\/span><\/span>Switchboard\u00a0<\/span><\/span><\/span> , etc., but some local designs and standards require its presence outside the facility or building, as shown in some of the previous pictures. <\/span>Also, there may be several bars\u00a0 <\/span><\/span>in\u00a0<\/span><\/span><\/span> several different distribution boards, so they are also all connected to each other.<\/span><\/span><\/p>\n

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    <\/figure>\n<\/div>\n

    7-\u00a0 <\/span><\/span>Removable Link<\/span><\/span><\/span> earthing system separation piece \u00a0for testing the resistance and validity of the ground rods.<\/span><\/span><\/p>\n

    B – Types of electrical grounding systems:<\/span><\/span><\/h2>\n

    After presenting the methods of connecting the various loads and pieces to the grounding points in the facility, you must know the relationship between those grounding points and the electrical distribution transformer, which will be explained in this part of the article.<\/span><\/span><\/p>\n

    There are different types of grounding systems and the choice of any of them determines the type or protection requirements for the electrical system and how it is connected to the loads. <\/span>These different types fall under three main types that are different from each other, and the network designer chooses any of them during his design of the electrical distribution system according to his needs and in accordance with the standards and requirements followed in his country. <\/span>Choosing the type of grounding system by the network designer will result in three important and independent decisions:<\/span><\/span><\/p>\n

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    • The method of connecting the neutral line in the network and its relationship to the apparent parts and pieces of the loads.<\/span><\/span><\/li>\n
    • Use a\u00a0 separate <\/span><\/span>Protective Earthing (PE)<\/span><\/span><\/span> line\/cable or combine \u00a0it with the neutral line and use only one cable.<\/span><\/span><\/li>\n
    • How to use ground fault protection devices (from a short circuit with earth or current leakage to earth) to separate the circuit or give an alarm of a ground fault.<\/span><\/span><\/li>\n<\/ul>\n

      The different earthing systems are also known as \u201cEarthing\u00a0 <\/span><\/span>System Arrangements<\/span><\/span><\/span> \u201d and describe the method of earthing the lower part of the network on the secondary end of the\u00a0 <\/span><\/span>MV\/LV Transformers<\/span><\/span><\/span> \u00a0(specifically the neutral connection\u00a0 <\/span><\/span>of\u00a0<\/span><\/span><\/span> the transformer) and how to earth the visible parts of the electrical connections connected to the network. <\/span>Grounding methods also describe whether the transformer’s neutral\u00a0 <\/span><\/span>(N)<\/span><\/span><\/span> \u00a0and protective conductor\u00a0 <\/span><\/span>(PE)\u00a0<\/span><\/span><\/span> are separate or connected together. <\/span>Finally, choose whether the use of a protective device for the increase in current is sufficient, or is there a need for a special protection to read and disconnect the circuit when the insulation of the conductors fails and there is a leakage current to the ground. <\/span>All these points have been combined together and covered by the standard as described throughout this article.<\/span><\/span><\/p>\n

      The\u00a0 <\/span><\/span>IEC 60364<\/span><\/span><\/span> standard \u00a0classifies the different grounding systems with two letters, the first letter of which identifies the method of connection between the ground and the current-providing equipment (whether it is an electrical transformer, generator, or other), while the second letter identifies the method of connection between the ground or the electrical network and the various electrical equipment (including loads) that are being fed. <\/span>The characters available according to the standard are as follows:<\/span><\/span><\/p>\n

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      • The letter\u00a0 <\/span><\/span>T<\/span><\/span><\/span> : symbolizes a direct connection with the ground, which is an abbreviation of the French word\u00a0 <\/span><\/span>Terre\u00a0<\/span><\/span><\/span> , which means \u201cland.\u201d<\/span><\/span><\/li>\n
      • The letter\u00a0 <\/span><\/span>I<\/span><\/span><\/span> : means the absence of any connection with the ground, or the presence of a connection with high resistance, which is an abbreviation of the word\u00a0 <\/span><\/span>isole\u00a0<\/span><\/span><\/span> in French and means \u201cisolation\u201d.<\/span><\/span><\/li>\n
      • The letter\u00a0 <\/span><\/span>N<\/span><\/span><\/span> : It symbolizes the connection of the neutral coming from the transformer, and it is an abbreviation for the French word\u00a0 <\/span><\/span>Neutre\u00a0<\/span><\/span><\/span> , which means \u201cneutral.\u201d<\/span><\/span><\/li>\n<\/ul>\n

        The first letter of the earthing system can only be either\u00a0 <\/span><\/span>T<\/span><\/span><\/span> \u00a0or\u00a0 <\/span><\/span>I<\/span><\/span><\/span> \u00a0, and the second letter can only be\u00a0 <\/span>\u00a0either <\/span><\/span>T<\/span><\/span><\/span> \u00a0or\u00a0 <\/span><\/span>N. <\/span><\/span><\/span>This just gives us the following combinations:<\/span><\/span><\/p>\n

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        • TT<\/span><\/li>\n
        • IT<\/span><\/li>\n
        • TN<\/span><\/li>\n
        • IN\u00a0<\/span><\/span><\/span> (it is a non-existent form because it is included in\u00a0 <\/span><\/span>IT\u00a0<\/span><\/span><\/span> as you will see later)<\/span><\/span><\/li>\n<\/ul>\n

          The standard also allows the presence of sub-letters following the grounding system\u00a0 , <\/span><\/span>TN\u00a0<\/span><\/span><\/span> , as follows:<\/span><\/span><\/p>\n

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          • TN-C<\/span><\/span><\/span><\/li>\n
          • TN-S<\/span><\/span><\/span><\/li>\n
          • TN-CS<\/span><\/span><\/span><\/li>\n<\/ul>\n

            Where the letter\u00a0 <\/span><\/span>C<\/span><\/span><\/span> is \u00a0an abbreviation for the word\u00a0 <\/span><\/span>Combined\u00a0<\/span><\/span><\/span> , i.e. combined, and the letter\u00a0 <\/span><\/span>S<\/span><\/span><\/span> is \u00a0an abbreviation for the word\u00a0 <\/span><\/span>Separate\u00a0<\/span><\/span><\/span> , i.e. separated. <\/span>Hence, we present all the installations of grounding systems in one picture, as you can see here:<\/span><\/span><\/p>\n

            <\/figcaption><\/figure>\n

            B1 \u2013\u00a0 <\/span><\/span>TT grounding system<\/span><\/span><\/span><\/h2>\n

            We first start by talking about the\u00a0 <\/span><\/span>TT<\/span><\/span><\/span> grounding system . As the type of this system indicates, the neutral end of the current-providing side (such as a transformer) is directly connected to the ground,\u00a0 <\/span><\/span>T<\/span><\/span><\/span> \u00a0, through an\u00a0 <\/span><\/span>electrode<\/span><\/span><\/span> . <\/span>Likewise, the grounding point on the side of the load is connected to a different grounding that is directly related to it through another ground rod, and this grounding includes the grounding of the\u00a0 <\/span><\/span>Protective Conductor<\/span><\/span><\/span> \u00a0and the\u00a0 <\/span><\/span>Extraneous Conductive Part<\/span><\/span><\/span> . <\/span>Also, the neutral point coming out of the transformer goes and is connected to the loads by means of a separate cable. <\/span>The only connection between the grounding and neutral of a transformer is that the two are connected together at the transformer end only. <\/span>Check out the picture of the\u00a0 <\/span><\/span>TT\u00a0<\/span><\/span><\/span> system to learn more about it.<\/span><\/span><\/p>\n

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            <\/figure>\n<\/div>\n

            The method used to protect humans from the ground leakage current in this system is by using a\u00a0 <\/span><\/span>Residual Current Device<\/span><\/span><\/span> \u00a0( <\/span><\/span>RCD<\/span><\/span><\/span> ), which is usually set (according to the standards for each country) to disconnect the circuit breaker when the amount of ground leakage current exceeds\u00a0 <\/span><\/span>30mA<\/span><\/span><\/span> . <\/span><\/span>TT\u00a0<\/span><\/span><\/span> earthing systems\u00a0 <\/span>separate the grounding line from the neutral allowing the use of four-phase circuit breakers, but it is necessary to ensure good soil between the loads and the transformer because the only path available for the earth-leaked current to return to the transformer is through the soil of the earth. <\/span><\/span>If the loads are earthed at more than one point (as in the picture), RCD\u00a0<\/span><\/span><\/span> protection must be provided\u00a0 <\/span>at each of these points.<\/span><\/span><\/p>\n

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            <\/figure>\n<\/div>\n

            The most important characteristics of this system can be summarized as follows:<\/span><\/span><\/p>\n

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            • It is the easiest in terms of design and installation.<\/span><\/span><\/li>\n
            • It does not require permanent monitoring of the grounding state during the network operation, but a periodic examination of the current leakage protection devices must be carried out.<\/span><\/span><\/li>\n
            • Protection against leakage current is ensured by the use of\u00a0 <\/span><\/span>RCDs\u00a0<\/span><\/span><\/span> , which also reduces the risk of fire.<\/span><\/span><\/li>\n
            • Any current leakage to the ground (such as the failure of the cable insulation, which causes it to connect to the ground or to the surrounding metal objects) will result in circuit separation and loss of the current load. <\/span>However, this separation will be limited to the load in which the problem occurred, according to the settings and timing of the separation of the\u00a0 <\/span><\/span>RCD\u00a0<\/span><\/span><\/span> circuit breakers connected in series.<\/span><\/span><\/li>\n
            • Some loads that by their nature produce a leakage current to the ground (such as welding machines) will disconnect the breaker frequently and undesirably during their work, so these loads will need a separate isolation transformer of their own, or that\u00a0 <\/span>specialized <\/span><\/span>RCD\u00a0 devices be used for them.<\/span><\/span><\/span><\/li>\n<\/ul>\n

              B2 \u2013 TN<\/span><\/span> grounding system\u00a0<\/span><\/span><\/h2>\n

              The TN\u00a0<\/span><\/span><\/span> system\u00a0 is <\/span>similar\u00a0 to the <\/span><\/span>TT\u00a0<\/span><\/span><\/span> system in the grounding point of the current source (transformer or generator) in terms of connecting the neutral point directly to the ground, but it differs in grounding the end of the loads. <\/span>In this system, ground poles planted or connected to the soil are not constructed from the load side (except in some exceptions as you will see below), but it is sufficient to use the neutral and\/or ground cable coming from the transformer for various grounding purposes. <\/span>This system is divided into three types according to the arrival of the neutral cable from the current source to the loads as follows:<\/span><\/span><\/p>\n

              TN-S<\/span><\/span> system\u00a0<\/span><\/span><\/p>\n

              In this system, five cables come out of the transformer, of which one cable is used as a neutral point for loads, while the second is used as a protective earthing <\/span>\u00a0( <\/span>PE<\/span><\/span> ) <\/span><\/span>cable . <\/span><\/span><\/span>It is one of the most popular and frequently used systems. <\/span>This system is mandatory by\u00a0 <\/span>IEC\u00a0<\/span><\/span> standard for circuits with a cable cross-sectional width of less than\u00a0 <\/span>10\u00a0<\/span><\/span> millimeters ( <\/span>mm2<\/span><\/span> ) or when portable devices (eg those connected to sockets) are used. <\/span>Underground wire sheathing or metal reinforcement can be used to connect\u00a0 <\/span>PE\u00a0<\/span><\/span> protection line and is generally applicable.<\/span><\/span><\/p>\n

              An example of using this system in electrical sockets is that one of the two cables is connected to the ground (\u00a0 <\/span><\/span>PE\u00a0<\/span><\/span><\/span> ) and the other to the point of the cold line,\u00a0 <\/span><\/span>N<\/span><\/span><\/span> , \u00a0as in the picture:<\/span><\/span><\/p>\n

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              <\/figure>\n<\/div>\n
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              <\/figure>\n<\/div>\n

              This system saves the costs of establishing an earthing network for each load or facility separately, but it requires an additional grounding cable from the transformer (through the distribution substation) to the loads.<\/span><\/span><\/p>\n

              TN-C<\/span><\/span> system\u00a0<\/span><\/span><\/p>\n

              It is completely similar to the previous system, except that instead of using two separate cables for neutral and ground, only one cable is used for the two purposes together, as in the picture below, and this cable is called the\u00a0 <\/span><\/span>Protective Earth and Neutral (PEN)<\/span><\/span><\/span> cable . <\/span>The disadvantage of this system is that if there is a need to open the current circuit breakers for the loads, the circuit breaker will separate the neutral and ground lines together (in order to ensure positive isolation of the\u00a0 <\/span><\/span>load<\/span><\/span><\/span> \u00a0), and this is not safe because the grounding point will lose the purpose of its existence. <\/span>Also, separating the hot lines only without separating the neutral line is not recommended because it is not a positive separation, in the sense that it will not separate all the lines or cables through which the short current may pass.<\/span><\/span><\/p>\n

              The standard does not prevent a separate grounding point\/bars from being provided at the end of the load and connected to the grounding line coming from the current source, and this also applies to the\u00a0 <\/span><\/span>TN-S<\/span><\/span><\/span> system \u00a0as well. <\/span>Also, it is forbidden to use the\u00a0 <\/span><\/span>TN-C<\/span><\/span><\/span> system \u00a0with a neutral and earth conductor with a cross section of less than\u00a0 <\/span><\/span>10\u00a0<\/span><\/span><\/span> square millimeters ( <\/span><\/span>mm2<\/span><\/span><\/span> ) and it is forbidden to use it with portable devices (such as those connected to sockets).<\/span><\/span><\/p>\n

              When using this system, care must be taken to have an environment with equal voltage\u00a0 <\/span><\/span>in\u00a0<\/span><\/span><\/span> the network, and that is done by planting earthing rods distributed at equal distances as much as possible, because the\u00a0 <\/span><\/span>PEN\u00a0<\/span><\/span><\/span> line will carry the neutral current and the\u00a0 <\/span><\/span>3rd Harmonic<\/span><\/span><\/span> currents . <\/span>Therefore it is necessary to connect the\u00a0 <\/span><\/span>PEN\u00a0<\/span><\/span><\/span> line with grounding.<\/span><\/span><\/p>\n

              \n
              <\/figure>\n<\/div>\n

              TN-CS<\/span><\/span> system\u00a0<\/span><\/span><\/p>\n

              Here we combine the two previous systems together, as only one cable comes out of the transformer, collecting the ground and neutral, and then it is divided in one of the distribution panels into two separate cables, as in the picture.<\/span><\/span><\/p>\n

              \n
              <\/figure>\n<\/div>\n

              In this system, it is forbidden to use the\u00a0 <\/span><\/span>PE\u00a0<\/span><\/span><\/span> ground line as a neutral point\u00a0 <\/span><\/span>N<\/span><\/span><\/span> \u00a0to feed the load after the point of separation of the neutral cable from the ground as shown in the picture below. <\/span>It is also forbidden to connect the ground and neutral lines together after their separation, because any unintended separation of the neutral cable at the top of the circuit, then it will result in the separation of the\u00a0 <\/span><\/span>PE<\/span><\/span><\/span> ground protection line \u00a0at the bottom of the circuit, which is dangerous and unacceptable.<\/span><\/span><\/p>\n

              \n
              <\/figure>\n<\/div>\n

              Below you can see how the breaker disconnects current in both\u00a0 <\/span><\/span>TN-C<\/span><\/span><\/span> \u00a0and\u00a0 <\/span><\/span>TN-S<\/span><\/span><\/span> systems . <\/span>In the\u00a0 <\/span><\/span>TN-C<\/span><\/span><\/span> system \u00a0, the current will not be separated from the neutral point of the load, because this point itself connects the ground protection line of\u00a0 <\/span><\/span>PE\u00a0<\/span><\/span><\/span> loads and should not be cut off under any circumstances, while this can be done in the\u00a0 <\/span><\/span>TN-S<\/span><\/span><\/span> system \u00a0because the neutral line is separated from the ground line.<\/span><\/span><\/p>\n

              Although Schneider’s\u00a0 <\/span><\/span>Electrical Installation Guide<\/span><\/span><\/span> specifies \u00a0a way to protect the circuit only by using circuit breakers to increase the current, it is possible to use circuit breakers to protect against leakage current, but after studying each load separately and carefully, and this point will not be discussed in this article.<\/span><\/span><\/p>\n

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              <\/figure>\n<\/div>\n

              The characteristics of the TN\u00a0<\/span><\/span><\/span> earthing system are\u00a0 <\/span>summarized as follows:<\/span><\/span><\/p>\n