My master's thesis is focused on grounding of HV switchgear. The aim of this work is to create a computer program intended for dimensioning of earthing networks. The earthing networks are the most convenient alternative in term of effective grounding and distribution of ponential. They are based on latiny a flat conductor network cables and connection of appliance parts to network. Introduction of the thesis is dedicated to explanation of grounding theory and to description of requirements essential for properly designed earthing system (dimensioning of earthing system). Following chapter brings description of computer program algorithm testing propriety of an assigned earthing network for a particular switchgear. The chapter also contains description of an user interface and explanation of all features, included in the program. Last part provides presentation of program utilization to particular numerical assignment.

This thesis is a case study of a 230 kV transmission line in Lao P.D.R. Grounding of electrical systems is essential for safety and reliability of the system. Several standards are developed for designing a grounding system when building new facilities but it is harder to find references when it is an expansion of an old system or when the area for grounding is inferior. The transmission line is routed over a high resistive limestone ridge, where the requirements from the design standard can not be fulfilled. During normal conditions, each tower can be properly grounded to earth with ground electrodes, but in this case the resistivity of the solid rock is too high. By studying different shield wires of different materials and improve the down lead conductor in each side of the mountain, a suitable solution can be found. The importance of grounding, general description of grounding techniques and the risks for human and equipment due to an electrical fault is also presented in this thesis.

Η παρούσα διπλωματική εργασία ασχολείται με τον έλεγχο και τη μέτρηση των γειώσεων από τα συστήματα αντικεραυνικής προστασίας των κτιρίων του Πανεπιστημίου Πατρών. Σκοπός του συστήματος γείωσης είναι να υλοποιεί την απαγωγή και διάχυση του ρεύματος από τον κεραυνό μέσα στη γη, χωρίς να δημιουργούνται επικίνδυνες υπερτάσεις που μπορεί να πλήξουν τον άνθρωπο ή τον εξοπλισμό. Στο πρώτο κεφάλαιο γίνεται περιγραφή βασικών εννοιών σχετικά με τα ηλεκτρικά φαινόμενα που εμφανίζονται στην ατμόσφαιρα. Συγκεκριμένα αναλύεται πως δημιουργούνται οι κεραυνοί και ποια είναι τα είδη τους, η συχνότητα των κεραυνικών πληγμάτων, οι συνέπειές τους και η αρχή λειτουργίας των αλεξικεραύνων. Στο δεύτερο κεφάλαιο περιγράφονται βασικές έννοιες για το σύστημα αντικεραυνικής προστασίας, πως γίνεται η σχεδίασή του, τα υλικά που απαιτούνται και πως καθορίζεται η στάθμη προστασίας για την εκάστοτε κατασκευή και τον εκάστοτε τόπο. Στο τρίτο κεφάλαιο περιγράφονται οι συνθήκες και η επίδρασή τους στο αποτέλεσμα των μετρήσεων όπως οι καιρικές συνθήκες και οι διάφοροι μέθοδοι μέτρησης των γειώσεων. Τέλος παρουσιάζονται οι μετρήσεις των γειώσεων από όλα τα κτίρια του Πανεπιστημίου Πατρών. Ακολουθούν τα συμπεράσματα αυτής της μελέτης και το παράρτημα με τις εικόνες που επισημαίνουν διάφορα σημεία του Πανεπιστημίου Πατρών. Τέλος παρουσιάζεται η βιβλιογραφική αναφορά των πηγών για αυτή την εργασία. / The subject of this study deals with the control and measurement of earthing systems of lightning protection of buildings in the University of Patras. The purpose of the grounding system is to implement the kidnapping and diffusion current from the lightning into the earth without creating dangerous power surges that can harm humans or equipment. The first chapter is a description of basic concepts relating to electrical phenomena that occur in the atmosphere. It is analyzed that generated lightning and what are their types, the frequency of lightning strikes, their consequences and the operating principle of lightning conductors. The second chapter describes basic concepts for the lightning protection system, the way that this system can be designed, the materials needed and how the level of protection can be determined for each building and each site. The third chapter presents the conditions and their effect on outcome measurements such as weather conditions and the various methods of earthing measurement. Finally measurements of the ground are presented from all the buildings in the University of Patras. Following the conclusions of this study, is included the appendix with images that highlight various points. At the end, is the bibliographic reference sources for this work.

This dissertation thesis deals with application of probabilistic approach to assessment of earthing system safety in distribution networks, especially for cases with common earthing of high and low voltage side of distribution transformers HV/LV. In these cases, the increased potential during fault might be transferred from high voltage to low voltage network and thus the individuals from public can be exposed to increased risk. Thus, for these cases were in this thesis defined expectable touch scenarios together with the resulting risk imposed on individuals from the public. Based on the results it seems that adoption of probabilistic approach for these cases of earthing systems might be more suitable compared to the conventional deterministic worst case approach. In accordance to the aims of the thesis, a thorough analysis of currently adopted probabilistic approaches was carried out as well and it was pointed out to some new possible simplifications in the adopted probabilistic based methodologies. For example, it seems that appropriate modelling of human body resistance by the full lognormal distribution is not completely necessary and similar results can be obtained when only the resistance for 50 % of population together with c3 and c4 fibrillation curves are used. Much of the work was also devoted to the determination of possible uncertainty of calculated risk of evaluated earthing system, especially due to inappropriate modelling of earthing system. The appropriateness of different earthing system modelling methods together with other parameters on the value of calculated risk was investigated through conducting sensitivity analysis. Based on the analysis results it seems, that due to using more, or less simplified modelling method, a possible underrating in the resulting risk of about 40 % (about half an order/decade) is expectable. On the other hand, the change of parameters related directly to calculation of fibrillation probability seems to exhibit greater change in calculated risk by up to units of orders/decades.

Bei Erdschlüssen in Mittelspannungsnetzen mit Resonanz-Sternpunkterdung wird der einpolige Fehlerstrom, genannt Erdschluss-Reststrom, oft von den Oberschwingungsanteilen dominiert. Dadurch wird in manchen Netzen die betrieblich festgelegte Obergrenze für den Erdschluss-Reststrom, auf deren Grundlage die Erdungsanlagen ausgelegt wurden, überschritten. Für eine Bewertung hinsichtlich des Personenschutz muss geprüft werden, ob dies eine Überschreitung der zulässigen Berührungsspannung nach DIN EN 50522 zur Folge hat. Dazu wird die erdpotenzialanhebende Wirkung der Harmonischen im Erdschluss-Reststrom für repräsentative Anordnungen untersucht. Dies wird mittels eines Modells realisiert und durch Messergebnisse verifiziert. Hierbei werden jeweils Aussagen zur charakteristischen Stromverteilung im Erdungssystem, den wirksamen Erdungsimpedanzen sowie zur resultierenden Erdungsspannung getroffen. Wesentliche Einflussfaktoren werden benannt und eine vom Fehlerort abhängige Risikobewertung durchgeführt. Im Ergebnis kann eine Vielzahl potenzieller Fehlerorte als grundsätzlich unkritisch eingestuft und somit umfangreiche Untersuchungen sowie Fehlinvestitionen vermieden werden.

Kenneth John Nixon, Student no: 9307628H, PhD thesis, Electrical & Information Engineering, Faculty: Engineering & the Built Environment. 2006. / The work presented extends and contributes to research in earthing and lightning protection and focuses on the transient behaviour of a driven rod earth electrode. Although previous work in this area has produced practical guidelines and models that may be used for lightning protection system design and analysis purposes, there has not been an investigation into the commonly encountered scenario of multiple layers of di erent soil types, particularly where high current densities cause ionisation to occur in the surrounding soil. In the research presented, the behaviour of a practical driven rod earth electrode subjected to peak impulse currents of up to 30 KA is analysed. Measurements obtained using a large-scale experiment arrangement are compared against results obtained using a time-domain circuit model simulation. It is shown that a single apparent resistivity value calculated from the steady state resistance equation and the measured steady state resistance can be used as a simpli cation for modelling the lightning current transient behaviour of a driven rod earth electrode in multi-layer soil. This represents a unique and valuable contribution to engineers working in the eld of earthing and lightning protection.

The connection of high penetrations of new low carbon technologies such as PV and electric vehicles onto the distribution network is expected to cause power quality problems and the thermal capacity of feeder cables may be exceeded. Replacement of existing infrastructure is costly and so feeder cables are likely to be operated close to their hosting capacity. Network operators therefore require accurate simulation models so that new connection requests are not unnecessarily constrained. This work has reviewed recent studies and found a wide range of assumptions and approximations that are used in network models. A number of these have been investigated further, focussing on methods to specify the impedances of the cable, the impacts of harmonics, the time resolution used to model demand and generation, and assumptions regarding the connectivity of the neutral and ground conductors. The calculation of cable impedances is key to the accuracy of network models but only limited data is available from design standards or manufacturers. Several techniques have been compared in this work to provide guidance on the level of detail that should be included in the impedance model. Network modelling results with accurate impedances are shown to differ from those using published data. The demand data time resolution has been shown to affect estimates of copper losses in network cables. Using analytical methods and simulations, the relationship between errors in the loss estimates and the time resolution has been demonstrated and a method proposed such that the accuracy of loss estimates can be improved. For networks with grounded neutral conductors, accurate modelling requires the resistance of grounding electrodes to be taken into account. Existing methods either make approximations to the equivalent circuit or suffer from convergence problems. A new method has been proposed which resolves these difficulties and allows realistic scenarios with both grounded and ungrounded nodes to be modelled. In addition to the development of models, the voltages and currents in a section of LV feeder cable have been measured. The results provide a validation of the impedance calculations and also highlight practical difficulties associated with comparing simulation models with real measurement results.

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.

This master thesis is focused on the design of earthing switch for the indoor three pole generator disconnector from IVEP, a.s. The main task of the theoretical part of the master thesis was mechanical and electrical calculations on the contact system and the design of two variants of earthing switch construction. It has been proposed two variants of earthing switch construction. The first variant included three earthing knives for each pole of earthing switch and the other variant included two earthing knives for each pole. The aim of the practical part of this diploma thesis was to create a model of the earthing switch for generator disconnector, to simulate the heating of the contact system by passing the short-circuit current and to prepare the production documentation. For modeling, calculations and simulations were used Autodesk Inventor 2018, Matlab and Ansys Workbench.

The following master thesis is devoted to the design of distribution systems of LV (Low Voltage) and HV (High Voltage) voltage levels. The aim of the thesis is to create a complete project documentation for the construction of a new distribution transformer station (22kV/0.4kV) situated directly in the city of Blansko along with a transformer capable of performance of up to 630kVA. Subsequently a design of cable routes of LV and HV is included in the project documentation. The first part of the thesis introduces the fundamental issues and solutions regarding the design of electrical equipment related to the LV and HV voltage levels. Thereafter it deals with proper legislation, technical regulations and related standards. The second part is dealing with project documentation. More precisely analyzing each step in the process and thoroughly going through individual parts of the project documentation. Other focus of the thesis is software resources and tools which are essential for drawing documentation. Then follows a selection of appropriate electrical equipment and budget evaluation. The major portion of the work is a design of distribution transformer station and cable lines of LV and HV. Including dimensioning of the LV and HV switchboards, earthing system and fuse protection system. The essence of all this work serves as a foundation for complete design documentation.