Earthing And Grounding System Pdf
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Calculating the cross-section of the ground wire for power stations. Hence the LPS designer and the LPS installer should make special provisions for protection against dangerous step voltages in the vicinity of the earth-termination networks if they are installed in areas accessible to the public see Clause 8. The resistance value should be as low as possible in every case but especially in the case of structures endangered by explosive material. Still the most important measure is equipotential bonding. Steel in concrete has approximately the same galvanic potential in the electrochemical series as copper in soil.
To connect the metallic conductive Parts of an Electric appliance or installations to the earth ground is called Earthing or Grounding. In other words, to connect the metallic parts of electric machinery and devices to the earth plate or earth electrode which is buried in the moisture earth through a thick conductor wire which has very low resistance for safety purpose is known as Earthing or grounding.
To earth or earthing rather, means to connect the part of electrical apparatus such as metallic covering of metals, earth terminal of socket cables, stay wires that do not carry current to the earth.
Earthing can be said as the connection of the neutral point of a power supply system to the earth so as to avoid or minimize danger during discharge of electrical energy. Good to know. Let me clear the confusion among earthing, grounding and bonding.
Earthing and Grounding are the same terms used for earthing. The word Bonding used for jointing two wires as well as conductors, pipes or appliances together.
Bonding is known as connecting the metallic parts of different machines which is not considered to be carrying electric current during normal operation of the machines to bring them at the same level of electric potential. The primary purpose of earthing is to avoid or minimize the danger of electrocution, fire due to earth leakage of current through undesired path and to ensure that the potential of a current carrying conductor does not rise with respect to the earth than its designed insulation.
When the metallic part of electrical appliances parts that can conduct or allow passage of electric current comes in contact with a live wire, maybe due to failure of installations or failure in cable insulation , the metal become charged and static charge accumulates on it. If a person touches such a charged metal , the result is a severe shock.
To avoid such instances, the power supply systems and parts of appliances have to be earthed so as to transfer the charge directly to the earth. This is why we need Electrical Earthing or Grounding in electrical installation systems.
Below are the basic needs of Earthing. Earthing is not done anyhow. A complete electrical earthing system consists on the following basic components. That part of the earthing system which interconnects the overall metallic parts of electrical installation e. The resistance of the earth continuity conductor is very low. Size of the Earth Continuity Conductor or Earth Wire depends on the cable size used in the wiring circuit.
The cross sectional area of the Earth Continuity Conductor should not be less than the half of the cross sectional area of the thickest wire used in the electrical wiring installation. Generally, the size of the bare copper wire used as earth continuity conductor is 3SWG.
Earthing lead is the final part of the earthing system which is connected to the earth electrode which is underground through earth connecting point. There should be minimum joints in earthing lead as well as lower in size and straight in the direction. Generally, copper wire can be used as earthing lead but, copper strip is also used for high installation and it can handle the high fault current because of wider area than the copper wire. A hard drawn bare copper wire is also used as an earthing lead.
In this method, all earth conductors connected to a common one or more connecting points and then, earthing lead is used to connect earth electrode earth plat to the connecting point.
To increase the safety factor of installation, two copper wires are used as earthing lead to connect the device metallic body to the earth electrode or earth plate. It should not be considered that the two earth leads are used as parallel paths to flow the fault currents but both paths should work properly to carry the fault current because it is important for better safety.
The size or area of earthing lead should not be less than the half of the thickest wire used in the installation. The earth lead connection methods is shown in the above fig.
Note: We will post additional article about Earth Plate size with simple calculations… Stay tune. A metallic electrode or plate which is buried in the earth underground and it is the last part of the electrical earthing system.
In simple words, the final underground metallic plate part of the earthing system which is connected with earthing lead is called earth plate or earth electrode. A metallic plate, pipe or rode can be used as an earth electrode which has very low resistance and carry the fault current safely towards ground earth. Both copper and iron can be used as earthing electrode.
The size of earth electrode In case of copper. In case of Iron. It is recommended to bury the earth electrode in the moisture earth. If it is not possible, then put water in the GI Galvanized Iron pipe to make possible the moisture condition. In the earthing system, put the earth electrode in vertical position underground as shown in the above fig. This action makes the possible increase in the size of the earth electrode which leads a better continuity in the earth earthing system and also helps to maintain the moisture condition around earth plate.
Good to know:. Since, the water level is different in the different areas; therefore, the depth for earth electrode installation is also different in various areas. But, the depth for earth electrode installation should not be less than 10ft 3 meter and should below 1 foot Motors , Generator , Transformers etc should be connected from to earth electrode two different places. The metallic pipe should be 2 meter below from the surface of ground.
To maintain the moister condition, put 25mm 1inch coal and lime mixture around the earth plate. For effectiveness and convenience, you may use the copper rods We will discuss the installation method of rod earthing latter. Earthing can be done in many ways. The various methods employed in earthing in house wiring or factory and other connected electrical equipment and machines are discussed as follows. In plate earthing system, a plate made up of either copper with dimensions 60cm x 60cm x 3.
For proper earthing system, follow the above mentioned steps in the Earth Plate introduction to maintain the moisture condition around the earth electrode or earth plate. A galvanized steel and a perforated pipe of approved length and diameter is placed vertically in a wet soil in this kind of system of earthing.
It is the most common system of earthing. The size of pipe to use depends on the magnitude of current and the type of soil. The dimension of the pipe is usually 40mm 1. The moisture of the soil will determine the length of the pipe to be buried but usually it should be 4.
A copper rod of The length of embedded electrodes in the soil reduces earth resistance to a desired value. In this method of earthing, the waterman Galvanized GI pipes are used for earthing purpose. Make sure to check the resistance of GI pipes and use earthing clamps to minimize the resistance for proper earthing connection.
If stranded conductor is used as earth wire, then clean the end of the strands of the wire and make sure it is in the straight and parallel position which is possible then to connect tightly to the waterman pipe. In this method of earthing, strip electrodes of cross-section not less than 25mm x 1. If copper with a cross-section of 25mm x 4mm 1in x 0. If at all round conductors are used, their cross-section area should not be too small, say less than 6.
The length of the conductor buried in the ground would give a sufficient earth resistance and this length should not be less than 15m. The usual method of earthing of electric equipments, devices and appliances are as follow:. Various specifications in respect to earthing as recommended by Indian Standards are given below.
Here are few;. As emphasized on earlier, earthing is provided in order. However, if excessive current is not earthed, appliances will be damaged without the help of fuse in place.
You should note that excessive current are earthed at their generating stations which is why earth wires carries very little or no current at all. It therefore implies that it is not necessary to earth any of the wires live, earth and neutral wires contained in a PVC. Earthing the live wire is catastrophic. I have seen a person killed simply because a live wire got cut from overhead pole and fell to the ground while the ground was wet.
Excessive current is earthed at generating stations and if at all the earthing is not efficient due to fault, earth fault interrupters will be there to help. Fuse help only when the power transmitted is above the rating of our appliances, it blocks the current from reaching our appliances by blowing off and protecting our appliances in the process. In our electrical appliances, if excessive currents are not earthed, we would experience severe shock.
Earthing takes place in electrical appliances only when there is a problem and it is to save us from danger.
If in an electronic installation, a metallic part of an electrical appliance comes in direct contact with a live wire that results from maybe failure of installation or otherwise, the metal will be charged and static charge will accumulate on it. If you happen to touch the metallic part at that moment you will be zapped. But if the metallic part of the appliance is earthed, the charge will be transferred to earth instead of accumulating on the metallic part of the appliance.
In addition, if a live wire touches accidentally in a faulty system to the metallic part of a machine. Now, if a man touches that metallic part of the machine, then the current will flow through their body to the ground, hence, he will get shocked electrocuted which may lead to serious injuries even to death. To be continued…. Thanks for share great info with us. I will recommend you to prefer plate earthing than pipe earthing. Plate earthing is the best earthing.
Outstanding blog, covering almost everything about the types of earthing! The importance of earthing, its types and fuse is very well explained. Hope to see such informative blogs more. Also for grounding electrical components, does it make any difference on the type of metal used in the grounding wire? Request if you can exclusively mention a pipe earthing for residential use for current ranging from 20 to 40 Amps.
A schematic diagram labelling dimensions, parts, quantity of charcoal, lime and salt. Can we get effective earthing of 8 feet digging out of 4 to 6 feet digging by adopting any suitable means. Thank you for your tutorials. It is very useful for me.
Difference Between Grounding and Earthing
One of the major difference between the grounding and the earthing is that in grounding, the current carrying part is connected to the ground whereas in earthing the non-current carrying parts is connected to ground. The other differences between them are explained below in the form of the comparison chart. The body of the equipment is connected to ground. Location Between the neutral of the equipment and ground Between the equipment body and earth pit which is placed under the earth surface. Protect the human from electric shock. Application Provide the return path to the current.
To connect the metallic conductive Parts of an Electric appliance or installations to the earth ground is called Earthing or Grounding. In other words, to connect the metallic parts of electric machinery and devices to the earth plate or earth electrode which is buried in the moisture earth through a thick conductor wire which has very low resistance for safety purpose is known as Earthing or grounding. To earth or earthing rather, means to connect the part of electrical apparatus such as metallic covering of metals, earth terminal of socket cables, stay wires that do not carry current to the earth. Earthing can be said as the connection of the neutral point of a power supply system to the earth so as to avoid or minimize danger during discharge of electrical energy. Good to know. Let me clear the confusion among earthing, grounding and bonding.
Earthing or grounding means connection of neutral point or body / enclosure of a system with the ground mass to avoid any accident & smooth functioning of.
Substation Earthing Design
In electrical engineering , ground or earth is the reference point in an electrical circuit from which voltages are measured, a common return path for electric current , or a direct physical connection to the earth. Electrical circuits may be connected to ground for several reasons. Exposed conductive parts of electrical equipment are connected to ground, so that failures of internal insulation which create dangerous voltages on the parts which could be a shock hazard will trigger protective mechanisms in the circuit such as fuses or circuit breakers which turn off the power. In electric power distribution systems, a protective earth PE conductor is an essential part of the safety provided by the earthing system.
Неисправность ТРАНСТЕКСТА угрожала и базе данных, а легкомыслие Стратмора не имело оправданий. Всем известно, что ТРАНСТЕКСТ и главная база данных АНБ тесно связаны между. Каждый новый шифр после его вскрытия переводится на безопасное хранение из шифровалки в главную базу данных АНБ по оптико-волоконному кабелю длиной 450 ярдов. В это святилище существует очень мало входов, и ТРАНСТЕКСТ - один из .
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