# Webinar "How to make a good grounding?", page 2

Webinar #6 of Electric energy saving and quality improvement" series

## Webinar text. Page 2

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 Располагаемая площадь Available area Пример относится к производственным корпусам, заводам, больницам, супермаркетам, стадионам, объектам ЖД и подстанциям The example is related to the production facilities, factories, hospitals, supermarkets, stadiums, railway facilities and substations Вокруг здания прокладывается горизонтальный контур длиной 160 м Horizontal circuit with the length of 160 m shall be laid around the building При удельном сопротивлении грунта 100 Ом*м Расчетное удельное сопротивление: 1,63 Ом At the soil resistivity of 100 Ohm*m Calculated soil resistivity: 1.63 Ohm С учетом непрерывной электрической связи колонн с арматурой фундаментов и присоединением к горизонтальному контуру By taking into account continuous electrical coupling of the columns with the foundation reinforcement and connection to the horizontal circuit Расчетное удельное сопротивление: 1,1 Ом Calculated resistivity: 1.1 Ohm

Available Area

—When selecting an earthing system, it would be more preferable to classify facilities  not by their load specifics, as Sergei Anatolyevich suggested at his webinars, but by the area they occupy. Therefore, another fundamental point is choosing a place to install an earthing system. Structures such as engineering works, factories, stadiums, supermarkets, railway facilities, substations, etc., can be equipped with a single earth loop installed around the perimeter which can immediately provide an earthing resistance of 1.2 – 1.4 Ohms or close to this value. On this slide, you can see an earth loop around the 30x50 m building. This loop provides the total resistance of 1.63 Ohm in the ground, such as, for example, loam with a resistivity of 100 Ohm*m.

Using a reinforced concrete foundation, attaching a horizontal loop to it and ensuring continuity of connecting the foundation reinforcements to each other, the earthing system resistance may be reduced to 1.1 Ohms, which corresponds to the recommended value for the energy-saving hardware. In other words, this is a very good value.

 Фундамент в агрессивных средах Foundations in aggressive media 1. Использование битумных, эпоксидных и оклеечных покрытий, которые усилены рулонами с защитной стенкой может значительно увеличить сопротивление заземления! 1. Use of bituminous, epoxy and glued coatings reinforced by rolls with a protective shield could increase the grounding resistance significantly! 2. Битумная и битумно-латексная гидроизоляция обычно не оказывает существенного влияния на сопротивление заземления. 2. Usually, bitumen and bitumen and latex hydro-isolations do not have a significant impact on the grounding resistance. 3. Естественное заземляющее устройство можно дополнить искусственными заземлителями для соответствия норме. 3. The natural grounding device may be supplemented by the artificial grounding devices in order to meet the standard. Чем агрессивнее среда, тем выше сопротивление заземляющего устройства из-за принятых защитных мер в соответствии со СНиП II-28-73! More aggressive the medium, higher the ground terminal resistance due to applied protective measures according to SNiP II-28-73! Технический центр Technical center

Foundations in Aggressive Environments.

— The use of reinforced concrete foundations is not always possible, as the earth resistance can increase significantly with the use of bitumen, epoxy and surface coatings insulated with protective coatings. As a rule, bitumen and bitumen/latex waterproof coatings have a very little effect on the earth resistance. If a glued covering impedes the process, its natural earthing can always be supplemented with a man-made one. It means that an earth loop installed around a building is not sufficient. It may be radiating at some distance, or you can install an additional earth loop in the form of grid cells, etc. Earth rods may be vertically driven in the grid intersection points. But we are going to turn to it a bit later. The use of coatings significantly increases the resistance of the foundation earthing system. Using it as the only available solution can be rather complicated. The most appropriate solution is to use artificial earthing. However, the corrosive environment, which makes the use of coatings mandatory, greatly affects and corrodes materials, such as standard steel and carbon steel. Therefore, corrosion-resistant materials, such as stainless steel and copper bonded steel, should be used. The only advantage of the corrosive environment is that, as a rule, soil resistivity is rather low and, therefore, the artificial earthing is quite limited, despite the fact that the foundation is coated.

 Что если размеры здания меньше What if the building dimensions are lower Например: жилой дом, офисное здание For example: residential building, office building Сопротивление до 1,3 Ом обеспечивает контур габаритами 40x60 м. The resistance of up to 1.3 Ohm is provided by 40 x 60 m circuit. Если горизонтальный контур длиной меньше 200 м в грунте 100 Ом*м, принимаются следующие меры: If the horizontal circuit with the length of below 200 m in the soil of 100 Ohm*m, the following measures shall be taken: 1. Устанавливаются вертикальные заземлители. Они позволят снизить сопротивление заземления на величину до 30%. 1. Vertical ground terminals are to be installed. These allow the grounding resistance reduction by the value of up to 30 %. 2. Устанавливаются электролитические заземлители 2. Electrolytic ground terminals are to be installed 3. Выполняется выносное заземление или замена грунта 3. Remote grounding or soil replacement shall be made

Options for Smaller Building Dimensions.

— As we can conclude by now, the 1.3 Ohm resistance provides a 40x60 m earth loop for soils with resistivity of 100 Ohm*m. The length of the horizontal earth loop may be less than 200 m for such buildings like laundries or any other small-sized facilities, for example, residential buildings or offices.

The following measures can be taken to standardize an earthing system: vertically driven earth rods, which reduce the earth resistance by 30%, chemical earth rods or the use of remote-driven earth rods. It may be done together with the soil replacement, but this measure is not always effective, since there are certain drawbacks. They were reviewed at E. M. Baselyan's webinars, where he spoke of very large ground areas required.

 Использование вертикальных электродов Use of vertical electrodes Горизонтальный контур без вертикальных электродов дает сопротивление 1,72 Ом Horizontal circuit without vertical electrodes provides the resistance of 1.72 Ohm. Добавление 10 вертикальных электродов снижает сопротивление до 1,4 Ом Addition of 10 vertical electrodes reduces the resistance down to 1.4 Ohm. Снижение сопротивления 22% Resistance reduction by 22 % Технический центр Technical center

Use of Vertically Driven Earth Rods

— Let's consider the options of vertically driven earth rods. Ten 6-meter earth rods were driven into the soil within a 15-meter area. As a result, the earthing system resistance was reduced from 1.72 Ohms to 1.4 Ohms, which is the recommended value for the energy-saving hardware. The resistance was reduced by 22%, which is quite good. Longer vertically driven earth rods can reach the water-bearing layers, thus reducing the earthing resistance even more. These ones were 6-meter long, but vertically driven earth rods can be 15 meters or more. In this case their number can be reduced. These are never installed along the whole loop, but only at four intersection points. This may be quite sufficient, but you'd better re-check it with calculations.

 Молниезащита Lightning protection При установке молниеприемников по периметру здания или прокладке сетки в соответствии с СО 153 и РД 34 вокруг здания прокладывается контур из горизонтального заземлителя. When installing the lightning arresters by the building perimeter or when laying the mesh in accordance with SO 153 and RD 34 the horizontal grounding circuit shall be laid around the building. При достаточной длине контура условия для установки УЭС уже выполнены! Proper circuit length provides enough compliance with the conditions for the ESH installation!

Lightning Protection

— The feasibility of the earthing system for the energy-saving hardware may be affected by a surge protection circuit. If a building is protected by vertical discharge interception rods mounted along its perimeter (they can be either installed on the building roof, or attached to the wall), and a surge protection circuit is installed around the building perimeter from the down conductor, downleads should be run through the building in 20-25 meters. A 20-meter distance meets the requirements of the industrial standard SO 153, and a 25-meter distance meets the requirements of the ruling document RD-34.

A surge protection circuit is installed along the perimeter of the entire building. It is sufficiently large for a building with specified dimensions (a factory or a plant). It immediately ensures a rated resistance of 1.2 – 1.4 Ohms, which is quite sufficient and no additional measures are required.

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