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Research by Electrical Engineer Ahmet Becerik ahmet.becerik@emo.org.tr 16-Importance of Grounding in High-Rise Buildings: The need for electrical energy for all types of building operating systems used in high-rise buildings, the necessity for some systems to operate without interruption, the distribution of multifaceted and large electrical power, and the provision of working and usage conditions that foresee a high level of safety in the building are required. To ensure the continuity of electrical systems and the safety of human life, live parts in electrical systems are insulated. Insulation failures occurring for various reasons in electrically operated devices and installations cause the metal and conductive bodies or fixing parts of the installations and devices, which are not directly related to the operation, to become live. Dangerous voltages called "touch voltage" and "step voltage" pose a life-threatening danger to operating personnel and anyone who may come into contact with electrical installations. In the event of a fault of this or similar nature, one of the measures to be taken to ensure human safety is grounding. In general, a grounding system in high-rise buildings must meet the following three requirements: \u2022 Lightning and short circuit protection: The grounding system must ensure human safety and prevent damage such as fire, flashover, and explosion caused by direct lightning strikes, as well as overheating caused by short-circuit currents. \u2022 Safety protection: The grounding system must be able to carry lightning and short-circuit currents and should not generate unacceptable step voltages and touch voltages. \u2022 Device protection and functionality: The grounding system must protect the electronic system by creating a low-impedance path through the devices on the circuit. Appropriate cabling, grouping, and shielding applications are extremely important in preventing damage to electrical devices. Although the necessary aspects for these three issues are generally defined separately, their implementation requires a combined system approach. In both low-voltage (LV) and high-voltage (HV) installations, the effectiveness and usefulness of grounding depend on its proper execution and its ability to function as intended when needed. It would be a grave mistake to disregard grounding systems during the preparation of electrical projects for high-rise buildings that generally house both LV and HV installations, and during the construction and operation of these installations. 17-A General Overview of Grounding Systems: Grounding is an electrical installation that provides the necessary ground potential to prevent humans, other living beings, and electrical equipment from being exposed to dangerous voltages, and to ensure the safe and reliable operation of the protected installation at its operating voltage. There are two points to consider in grounding: a) Ensuring that the resistance (ground electrode transition resistance, spreading resistance) between the device or section to be grounded and the reference ground (a ground surface quite far from the electrode of the grounded object) is as small as possible; b) Ensuring that no potential difference occurs between devices, building equipment, and similar elements during operation. Today, in low-voltage installations, there are safer and more effective protection methods than grounding that utilize fault current and fault voltage. In contrast, in high-voltage installations, grounding is the only protection method against fault voltages. Types of Grounding: Grounding systems used in electrical installations, application areas, EMO Izmir branch, April 36, 2011, Electrical Engineering in High-Rise Buildings - VIII, \u201cGrounding Systems\u201d research, 18.2 - Grounding Electrode Sizing and Grounding Electrode Materials: The minimum dimensions required for grounding electrodes in terms of mechanical strength and corrosion, and the necessary conditions to be met, are determined in the Regulation on Grounding in Electrical Installations. If the smallest dimensions are used, the soil near the grounding electrodes should not heat up beyond the permitted value. For grounding electrodes located in the ground, hot-dip galvanized steel, copper (galvanized or tinned), or lead-coated copper can be used as materials. When a different material is chosen due to special conditions, it should be as reliable as the materials described above under normal conditions. The selection of grounding electrode material requires consideration of electrode cost and service life. Material corrosion and susceptibility to corrosion are two main factors determining the service life of a grounding system. Typical ground electrodes used as grounding electrodes are given below: \u2022 Simple surface ground electrodes - horizontally placed flat or ring-shaped strip or wire electrodes. \u2022 Rod (Vertical) electrodes - electrodes of sufficient length passing through soil layers with different conductivity; particularly suitable for thinner layers with lower conductivity compared to thicker layers. Preferred for areas with limited surface area where the ground electrode is to be placed. In installations consisting of common networks, the grounding system must meet the requirements for each installation in the network. 18.1-Construction of Grounding Lines: Neither fuses nor disconnectors can be placed on grounding connection conductors; these conductors are sized to withstand possible ground currents. Conductors connecting the electrode to the grounding point or installation should, as far as possible, be of the same type as the electrode's metal. Grounding conductors and connections should be easily identifiable. In parts not buried in the ground, these conductors should be accessible along their entire length to ensure inspection, separated from fire-hazardous parts of buildings, and protected against corrosion and mechanical impacts. Where possible, grounding conductors should avoid sharp bends. Grounding systems have different purposes and areas of application. Grounding is carried out in accordance with the following specifications: 1. Protective grounding: Grounding of the inactive metal parts of operating equipment to protect people from dangerous touch voltages. 2. Operational grounding: Grounding of the operating current circuit for the normal operation of the facility. 3. Functional grounding: Grounding performed to enable a communication facility or an operating element to perform its desired function. Protection against lightning effects, railway system grounding, grounding of low-current devices. 18-Sizing of Grounding Systems: Grounding systems should be sized according to the thermal load and the voltage in the grounding system. The grounding and touch voltages of a grounding system are calculated from known values such as the specific ground impedance and resistance. The dimensions of the grounding system are determined by the current passing through this section of the grounding system during a fault, the protection devices, and the tripping time of the circuit breakers during normal operation. This condition has different nominal voltages and top-emo Izmir branch 37 April 2011 research \u2022 Braided electrodes - electrodes usually placed horizontally in a mesh shape at a shallow depth below the ground \u2022 Ground electrode effective cable - a cable in contact with the ground with an open sheath or armored ground, similar in resistance to a strip-type ground electrode \u2022 Foundation ground electrodes - conductive metal parts embedded in concrete in contact with the ground over a large area 18.2.1-Foundation Grounding Application: Foundation ground electrodes are metal conductive parts embedded in the concrete structure of the building. Concrete parts embedded in the ground naturally contain a certain amount of moisture and their conductivity properties are considered to be close to soil conductivity. Since the area of these types of electrodes is large, their resistance is expected to be low. In addition, concrete protects the metal parts against corrosion, and steel electrode elements embedded in concrete do not need to be additionally protected against corrosion. Foundation ground electrodes are now applied as a very practical solution for building grounding. There are two main applications for foundation grounding in buildings: \u2022 Foundations without rebar \u2022 Foundations with rebar The ground electrode material used for both applications is: \u2022 Rectangular steel strip with a cross-section no smaller than 30mm x 3.5mm \u2022 Round steel bar with a cross-section no smaller than 10mm Steel elements can be zinc-coated (galvanized), but if the thickness of the concrete surrounding the electrode is more than 50 mm, zinc coating is not necessary due to the corrosion-protective properties of the concrete. In a foundation without rebar, the electrode is usually placed along the perimeter of the building, under the foundation walls. In buildings with wide foundations, the electrodes are usually in the form of interconnected rings along the foundations. In a building with rebar, the ground electrode is placed at the very bottom of the braided rebar, thus providing protection against corrosion of the electrode. A similar foundation is also available within the building's insulation. The electrode is connected to the reinforcing steel with wire at intervals along the electrode, with a distance of no more than 2m between them. Since the main electrical conduction will be through the concrete, the electrode-reinforcement steel connections do not need to be electrically robust. If the building foundations are constructed in separate panels connected by expansion joints, the electrode of each panel must be galvanically connected to the others. These connections should be easily accessible for ease of measurement and maintenance. The foundation ground electrode terminal must be at least 150cm above ground level. The terminal should be as close as possible to the main junction point of the building's electrical system. The main connection of the foundation ground electrode to lightning protection must be outside the building. References: \u2022 Safety and Grounding in Electrical Installations - Prof. Dr. Mustafa \u0130lisu-Bayram - Electrical Engineer EMO Publication - 2004\/Istanbul \u0130sa \u2022 Grounding Analysis in High Voltage Electrical Installations - Fato\u015f \u00dcresin - Unpublished Master's Thesis - KTU\/Institute of Science - 2010 \u2022 A Systems Approach for Grounding - Reyer Venhuizen - lPQ\u0130 - Sarkuysan A.\u015e. Publication - 2002 \u2022 Basic Construction Calculations of Grounding Systems - Henry Markiewicz - Antoni Klajn - lPQ\u0130 - Sarkuysan A.\u015e. Publication - 2004 \u2022 ETTY\/What the New Regulation Brings - Electrical Engineer \u0130sa \u0130lisu - EMO \u0130zmir Event Presentation EMO \u0130zmir Branch 38 April 2011<\/pre>\n
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