Γείωση είναι η αγώγιμη σύνδεση ενός σημείου κάποιου κυκλώματος ή ενός μη-ρευματοφόρου μεταλλικού αντικειμένου μιας εγκατάστασης με το έδαφος, με σκοπό να αποκτήσουν το ίδιο δυναμικό με τη γη, το οποίο θεωρείται –κατά σύμβαση- ίσο με μηδέν. Σκοπός ενός συστήματος γείωσης είναι να μεταφέρει και να διαχέει το ρεύμα σφάλματος στη γη, εμφανίζοντας τη μικρότερη δυνατή αντίσταση στη διέλευση του ρεύματος στον ελάχιστο δυνατό χρόνο. Με αυτόν τον τρόπο ελαττώνεται ο κίνδυνος ηλεκτροπληξίας και παρέχεται ασφάλεια κατά την εκδήλωση σφάλματος ή σε περίπτωση κεραυνού, τόσο για τους χρήστες όσο και για τον εξοπλισμό της ηλεκτρολογικής εγκατάστασης. Αποτελεί απαραίτητο τμήμα των ηλεκτρικών εγκαταστάσεων για να εξασφαλιστεί η σωστή λειτουργία τους αλλά και η ποιότητα της παρεχόμενης ηλεκτρικής ισχύος. Τέλος παρέχει ένα δυναμικό αναφοράς για τα ηλεκτρικά σήματα στον τομέα των τηλεπικοινωνιών. Για να επιτευχθούν οι παραπάνω στόχοι πρέπει η αντίσταση γείωσης να έχει πολύ χαμηλή τιμή. Υπάρχουν περιπτώσεις που είναι αδύνατη η τοποθέτηση περισσοτέρων του ενός ηλεκτροδίου διότι η εργασία είναι αρκετά δαπανηρή , είτε λόγω της δομής του εδάφους, είτε λόγω του ανεπαρκή χώρου. Μια εναλλακτική μέθοδος που έχει αναπτυχθεί είναι η χρήση βελτιωτικών υλικών γείωσης γύρω από τα ηλεκτρόδια. Στην παρούσα διπλωματική εργασία τοποθετήθηκαν ηλεκτρόδια γείωσης στο χώρο του Πανεπιστημίου Πατρών και έγινε μέτρηση των αντιστάσεων τους, με σκοπό τη μελέτη της συμπεριφοράς διαφόρων βελτιωτικών υλικών γείωσης σε συνάρτηση με το χρόνο και τις περιβαλλοντικές συνθήκες. Ειδικότερα η διπλωματική αυτή εργασία αποτελείται από τα εξής κεφάλαια: Στο κεφάλαιο 1 πραγματοποιείται μια αναφορά στην ορολογία και στις βασικές αρχές που διέπουν τα συστήματα γείωσης. Ακόμη γίνεται αναφορά στα είδη των ηλεκτροδίων γείωσης και στις διατάξεις που υπάρχουν. Δίνεται επίσης ο ορισμός της αντίστασης γείωσης και παρουσιάζονται οι μέθοδοι μέτρησης της τιμής της.Στο κεφάλαιο 2 περιγράφεται η έννοια και ο ορισμός της ειδικής αντίστασης εδάφους. Στην συνέχεια παρουσιάζονται οι παράγοντες που την ειδική αντίσταση επηρεάζουν και γίνεται αναφορά στους τρόπους μέτρησης της. Τέλος αναφέρονται τρόποι διόρθωσης της αντίστασης γείωσης σε περίπτωση που οι τιμές τις είναι εκτός των επιτρεπτών ορίων. Στο κεφάλαιο 3 γίνεται αναφορά στα βελτιωτικά υλικά γειώσεων και στις βασικές αρχές που τα διέπουν. Επίσης παρουσιάζεται το βελτιωτικό που χρησιμοποιήθηκε στην παρούσα διπλωματική εργασία. Στο κεφάλαιο 4 αναφερόμαστε στα όρια ασφάλειας που πρέπει να πληροί ένα σύστημα γείωσης. Περιγράφεται η αντίσταση του ανθρώπινου σώματος καθώς και οι παράγοντες που επιδρούν στην περίπτωση ηλεκτροπληξίας. Τέλος, με την βοήθεια των ισοδύναμων κυκλωμάτων κατά την διάρκεια του βραχυκυκλώματος δίνονται τα επιτρεπτά όρια τάσης επαφής και βηματικής τάσης. Στο κεφάλαιο 5 περιγράφεται η διεξαγωγή του πειράματος με αναφορά στην εγκατάσταση και στην διαδικασία μέτρησης των ηλεκτροδίων. Στην συνέχεια γίνεται επεξεργασία των μετρήσεων με χρήση διαγραμμάτων. Τελικά καταλήγουμε σε χρήσιμα συμπεράσματα και γίνονται κάποιες προτάσεις για προέκταση της συγκεκριμένης διπλωματικής εργασίας. Τέλος, η διπλωματική εργασία ολοκληρώνεται με το Παράρτημα, στο οποίο δίνονται αναλυτικά οι πίνακες με τα μετεωρολογικά δεδομένα την περίοδο που πάρθηκαν οι μετρήσεις. / Grounding is the conductive connection of a circuit’s point, or of a non-current carrying metallic object of an installation to the ground, in order to obtain the same potential as the earth, which is, by convention, equal to zero. The objective of a grounding system is to transfer and dissipate the fault current to earth, showing the least possible resistance to the passage of current to the minimum possible time. Thereby decreasing the risk of electric shock and provide security in the event of error or in case of lightning, both for users and for the installation of electrical equipment. Finally, provides a reference potential for the electrical signals in the telecommunications sector. To achieve these objectives, the grounding resistance should have very low value. There are cases where it is impossible to insert more than one electrode because the process is quite expensive, either because of the structure of the soil, either because of insufficient space. An alternative method that has been developed is the use of ground enhancing compounds around the ground electrodes. In this diploma thesis grounding electrodes placed in the university of Patras and their resistance was measured, with the aim of studding the behavior of various materials ground improvement in relation to time and environmental conditions. The earthing system is an essential part of power networks, is required for correct operation of the electricity supply network and to ensure good power quality. Specifically this thesis consists of the following chapters: Chapter 1 includes a reference to the terminology and basic principles of grounding systems. Also is referring to the existing types of grounding electrodes and their arrangements. It also gives the definition of ground resistance and presents methods of measuring its value. Chapter 2 describes the concept and definition of soil resistivity. Then follow the factors that affect resistivity and are mentioned ways of measurement. Finally it is mentioned the way of improving the ground resistance if the measured values are unacceptable. Chapter 3 refers to the ground improvement materials and their principles. Also it is presented the ground enhancing compound which was used in this diploma thesis. Chapter 4 is referring to the safety limits of a grounding system. Therefore is described the resistance of the human body and the affecting in case of electric shock. Finally, with the help of equivalent circuits during short circuit the permissible values of touch and step voltages. Chapter 5 describes to the experiment procedure referring to the installation and the process of the measurements. Then follows the processing of the measurements with diagrams. Eventually we arrive at useful conclusions and made some suggestions for extension of this thesis.Finally, in the Appendix there are the meteorological data for the months during which the experiment took place.

Master's thesis deals with principles of design of earthing of a substation 110/22 kV. Specific requirements for safety have to be fulfilled when designing power installations exceeding 1kV. The aim of this paper is to design a new earthing system for reconstructed substation 110/22kV considering valid standards. Reconstruction of a property is always more or less complicated by new orders and regulations for construction. Earthing is a part of all electric equipment, therefore it is essential for the design engineer to consider a broad spectrum of requirements, even those seemingly not related to this subject, from legislative requirements to the study of reactions of a human body to electric current. The theoretical part of this work examines different approaches to earthing system's design, and analyzes the origins and earthing standards throughout history. The correctness in consideration of effects of the environment is an often neglected factor. Defining of all types of effects of the environment is a broad field, therefore this paper only summarizes the main principles. The practical part of this paper deals with the basic design of substation's earthing system and it's verification in respect of touch voltage and step voltage according to the Czech national standard ČSN 33 3201 (Power installations exceeding 1kV a.c.) and of company's energetics' standard PNE 33 0000-1 ed.4 (Protection against electric shock in distribution network and transmission system) required by the substation's distributor. This paper later quotes and takes into consideration the requirements of other standards, more or less related to listed documents, creating an interconnected body for design and testing the earthing system.

Die Auslegung von Erdungsanlagen nach der DIN EN 50522 basiert im Wesentlichen auf der Bewertung der bei Erdfehler auftretenden Erdungs- bzw. Berührungsspannungen. Deren Berechnung setzt die Kenntnis der Fehlerstromaufteilung (bzw. der wirksamen Reduktionsfaktoren) voraus, da nur der Stromanteil, der als Erdungsstrom über der Erdungsimpedanz wirksam wird, tendenziell gefährliche Potentialanhebungen verursacht. Maßgebend für die Verteilung der Ströme im Erdungssystem sind die induktiven Kopplungen zwischen dem fehlerstromführenden Leiter und den zum Sternpunkt zurückführenden Strompfaden. Daraus geht hervor, dass sowohl die räumliche Anordnung der Leiter als auch die Frequenz der Fehlerstromanteile die vorherrschenden Verhältnisse entscheidend beeinflussen. Beide Einflüsse werden in den Standards und der Fachliteratur bis dato nur bedingt betrachtet. Diese Arbeit befasst sich daher mit der rechnerischen Bestimmung und Bewertung der Potentialanhebungen, welche sich im Falle eines Erdfehlers in Abhängigkeit von den Frequenzanteilen des Fehlerstroms in unterschiedlich aufgebauten Erdungssystemen ergeben. Wesentlicher Bestandteil der Ausführungen ist die Entwicklung eines Modells zur Berechnung der frequenzabhängigen Stromverteilung und den daraus resultierenden Erdungsspannungen in verbundenen Erdungsanlagen. Dieses bildet, in Erweiterung zu bestehenden Ansätzen, insbesondere den Einfluss der dreidimensionalen Anordnung der Leiter auf deren magnetische Kopplungen ab. Durch theoretische Betrachtungen und begleitende Messungen werden die Grenzen derartiger rechnerischer Bewertungsverfahren aufgezeigt. Anhand einfacher Modellanordnungen wird beispielhaft der Einfluss der räumlichen Struktur des Erdungssystems auf die frequenzabhängige Fehlerstromverteilung, die wirksamen Erdungsimpedanzen und die resultierenden Erdungsspannungen analysiert. Dabei werden explizit Erdfehler an zusammengeschlossenen Hoch- und Niederspannungs-Erdungsanlagen untersucht. Die Ergebnisse zeigen, dass rein zweidimensionale Berechnungsverfahren den theoretischen Worst-Case hinsichtlich der Erdungsspannung nicht abdecken. Für die praktische Anwendung des Modells werden sowohl Vereinfachungen als auch zusätzliche Sicherheitsaufschläge abgeleitet. Weiterhin erfolgt die modellbasierte Untersuchung einpoliger Fehler in voll- und teilverkabelten Netzen. Im Fokus steht dabei die potentialanhebende Wirkung der Frequenzanteile des einpoligen Fehlerstroms. Es wird aufgezeigt, dass infolge der induktiven Kopplungen ein hoher Anteil des Rückstroms in den beidseitig geerdeten Schirmen der fehlerstromführenden Kabel fließt. Bedingt durch die Frequenzcharakteristik des Reduktionsfaktors wirken die höherfrequenten Anteile des Erdfehlerstroms in vollverkabelten Netzgebieten in deutlich geringerem Maße potentialanhebend als der Grundschwingungsanteil. Daher lassen sich insbesondere für die Erdungssysteme von Kabelnetzen mit Resonanz-Sternpunkterdung vereinfachte Bewertungsmethoden ableiten. In Summe liefert diese Arbeit einen Beitrag dazu, wie der rechnerische Nachweis zulässiger Berührungsspannungen geführt und das Prozedere zur Auslegung von Erdungsanlagen vereinfacht werden kann. / The design of earthing installations in European high voltage grids has to comply with the standard EN 50522. The determining quantities for the risk assessment are the touch and step voltages occurring during an earth fault. Since the direct estimation of these voltages is complicated, earthing installations are usually assessed by means of the earth potential rise. For the calculation of the earth potential rise the knowledge of the fault current distribution (or the effective reduction factors) is required, since only the proportional current to earth raises the potential of the earthing installations. The inductive coupling between the conductor carrying the fault current and the current paths leading back to the neutral point is decisive for the distribution of the currents in the earthing system. This indicates that both the spatial arrangement of the conductors and the frequency of the fault current components have a determining influence on the prevalent conditions. To date, both influences have only been considered to a minor extent in the standards and technical literature. This thesis relates to the calculation and evaluation of the earth potential rises in differently structured earthing systems. Thereby, the varying potential raising effect of the harmonics in the earth fault current is examined. For this purpose, a model for the calculation of the frequency-dependent current distribution in interconnected earthing installations is developed. In extension to existing approaches, this model particularly represents the influence of the three-dimensional arrangement of the conductors on their magnetic coupling. Through theoretical considerations and accompanying measurements, the limits of such calculational evaluation methods are demonstrated. Based on simple model arrangements, the influence of the spatial structure of the earthing system on the frequency-dependent fault current distribution (reduction factors), the effective impedances to earth and the resulting earth potential rise is analysed exemplarily. Thereby, earth faults at interconnected high-voltage and low-voltage earthing installations are investigated explicitly. The results show that two-dimensional calculation methods do not cover the theoretical worst case regarding the earth potential rise. For the practical application of the model, simplifications as well as additional safety surcharges are derived. Furthermore, model-based investigations of single-pole faults in fully and partially cabled grids are carried out. The focus is on the potential-raising effect of the harmonic components of the single-pole fault current. It is shown that, due to inductive coupling, a high percentage of the return current flows via the shields of the cables carrying the fault current. Due to the frequency characteristic of the reduction factor, in fully cabled grid areas higher-frequency components of the earth fault current have a significantly lower potential-raising effect than the fundamental component. Particularly for the earthing systems of cable grids with resonant earthing, simplified assessment methods can thus be derived. In summary, this thesis provides a contribution on how to proof permissible touch voltages by calculation and how to simplify the procedure for the assessment of earthing installations in perspective.

The main topic of the thesis is the design of single-track electrification of a direct current system of 3 kV and an alternating current system of 5 kV 50 Hz and then economically evaluate it over a period of 30 years. The work deals with basic traction systems and also deals with the calculation of main parameters of electric trains. The thesis describes in detail the procedure for the design of the electrification of the track and a partial introduction to the simulation programs that were used for energy calculations.

This Thesis is concerned with the concept of grounding of 110/22 kV transformer station. The aim of the Thesis is to create a ground network for grounding a specified outdoor substation. This 110 kV outdoor substation is formed according to H-scheme and encircles a wide area. In additon to this, an earth potential has to be distributed as equally as possible within the whole area of the substation. The most convenient alternative from the point of view of effective grounding and distribution of potential is a grid network. Therefore, the grid network is the means of grounding which I have chosen as a solution for this issue. In this solution, flat conductor network cables are used to cover the whole substation, with ground rods placed at the points of intersection. Parts of appliance can be then connected to this existing network, thus creating several parallel channels which provide grounding with low resistance. The network is made of common steel zinc-coated stip, size 30 x 4 mm. When proposing a concept of grounding and adjustment of ground electrodes, we have to take account of grounding requirements, stated according to ČSN standards. The proposed earthing system was created in appropriate size in order to meet all these grounding requirements. These requirements are also mentioned and described in a theoretical part of the Thesis. Second part of the Thesis consists of proposed concept of the grounding itself, together with calculated parameters. The grounding has to be carried out according to both safety regulations and electrical appliance requirements. The issue of grounding substations of power system is resolved by the ČSN standards 33 3201 (“Elektrické instalace nad AC 1kV”), 33 2000-4-41 (“Elektrická zařízení – Ochrana před úrazem elektrickým proudem”) and 33 2000-5-54 (“Elektrická zařízení – Výběr a stavba elektrických zařízení – Uzemnění a ochranné vodiče”) and by the PNE company standards 33 0000-4 (“Příklady výpočtů uzemňovacích soustav v distribuční a přenosové soustavě dodavatele elektřiny”) and 33 0000-1 (“Ochrana před úrazem elektrickým proudem v distribuční soustavě dodavatele elektřiny”). These standards apply to creating a concept of grounding and grounding of new, reconstructed or expanded electrical substations of power system.

Submitted by SBI Biblioteca Digital (sbi.bibliotecadigital@puc-campinas.edu.br) on 2018-02-19T16:48:56Z No. of bitstreams: 1 CAMILA MADEIROS ALCANTARA PIMENTA.pdf: 4765494 bytes, checksum: dac59f354329911b1dfcb8422a61af1b (MD5) / Made available in DSpace on 2018-02-19T16:48:56Z (GMT). No. of bitstreams: 1 CAMILA MADEIROS ALCANTARA PIMENTA.pdf: 4765494 bytes, checksum: dac59f354329911b1dfcb8422a61af1b (MD5) Previous issue date: 2017-12-15 / Electrical grounding is part of the Atmospheric Discharge Protection System (ADPS), whose functions are to provide a path for the circulation of electric current in the ground and to enable the detection of a possible fault between the energized conductors and the earth. For grounding to be efficient, some characteristics must be taken into account, such as soil type and resistivity. In this sense, measurements of resistivity and soil stratification are important for a correct sizing of the grounding system. Soils with high water concentration (low resistivity) are better current conductors than dry soils, for example. Soils with high resistivity can cause a return current. Thus, some decisions aimed at strengthening the grounding system should be taken when there are soils with inadequate grounding characteristics. Therefore, this work aims to evaluate the influence of soil electrical resistivity and enveloping types using concrete types in the substation electrical grounding system through software simulations, taking into account soil resistivity characteristics. In the analysis of types of envelopment, it was possible to observe that the concretes with greater amount of water in their composition have a lower electrical resistivity. The use of concrete enveloping is feasible for soils with high resistivity, as in the case of the land located in the city of Campinas, and it was possible to verify that for soils with low resistivity its use may be impractical since other options such as inclusion of more cables and installation of the rods in the layers with less resistivity are sufficient and more economical. / O aterramento el?trico faz parte do Sistema de Prote??o Contra Descargas Atmosf?ricas (SPDA), cujas fun??es s?o fornecer um caminho para a circula??o de corrente el?trica na terra, escoamento para a terra de cargas induzidas nas carca?as dos equipamentos el?tricos e, em conjunto com os dispositivos diferenciais-residuais, possibilitar a detec??o de uma poss?vel falha entre os condutores energizados e a terra. Para que o aterramento seja eficiente, algumas caracter?sticas devem ser levadas em considera??o, tais como o tipo e a resistividade do solo. Neste sentido, medi??es da resistividade e a estratifica??o do solo s?o importantes para um dimensionamento correto do sistema de aterramento. Solos com alta concentra??o de ?gua (baixa resistividade) s?o melhores condutores de corrente do que um solo seco, por exemplo. Solos com alta resistividade podem ocasionar uma corrente de retorno. Assim, algumas decis?es visando o refor?o do sistema de aterramento devem ser tomadas quando se tem solos com caracter?sticas inadequadas ao aterramento. Portanto, esse trabalho teve como objetivo avaliar a influ?ncia da resistividade el?trica do solo e de tipos de envelopamento utilizando tipos de concreto no sistema de aterramento el?trico de subesta??es atrav?s de simula??es em software, levando em conta as caracter?sticas de resistividade do solo. Nas an?lises de tipos de envelopamento, foi poss?vel observar que os concretos com maior quantidade de ?gua em sua composi??o possuem uma resistividade el?trica mais baixa. A utiliza??o do envelopamento de concreto ? vi?vel para solos com alta resistividade, como ? o caso do terreno localizado na cidade de Campinas, e foi poss?vel verificar que para solos com resistividade baixa sua utiliza??o pode ser invi?vel j? que outras op??es como inclus?o de mais cabos e instala??o das hastes nas camadas com menor resistividade s?o suficientes e mais econ?micas.