The main subject of this diploma’s thesis is the creation of laboratory task on the partial discharge. The thesis is made up of two parts: theoretical and practical. In the theoretical part there are information about partial discharge. One of them is classification partial discharge by type, effects of partial discharge in insulation systems, parameters to assess the quality of electrical insulation of power systems and measurement techniques. Further part is user’s manual for measurement instrument. In practical part is created laboratory task on problematic of the partial discharge measurement. It is demonstrative measure of partial discharge with the aim of understanding problematic of partial discharge, calibration and noise.

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The continuous increase of the voltage levels in power transmission systems has lead to the occurrence of higher switching transients during their operation. The design of equipment and grid components able to sustain such a stressful operation, requires an intensive study of the electric field stress generated by these transients, and their distribution to the vicinity of each configuration. Sphere-plane gaps are the most theoretically and practically interesting electrode configurations. So far, the majority of the conducted work is referred to the study of the discharge characteristics of this structure. However, a study of the electrostatic electric field is required. An accurate calculation of the electric field can contribute significantly to an even better understanding of the discharge characteristics and the principles behind them. In this project, is presented a simulation approach for the calculation of the electro-static field of a sphere-plane configuration, varying the dimensions of the sphere and the gap distance. For this purpose, a Finite Element Method (FEM) solver was used, in which the configuration was designed and the numerical solution of the problem was implemented. After that, an attempt was performed to specify the breakdown voltage based on the electric field calculation and distribution. Useful results were recorded from both the simulation of the electrostatic model and the calculation of the breakdown voltage. One of the most important findings, was the specification of an approximate relation between the diameters of the sphere and the tube where this is mounted. As a consequence, the study of the electric field distribution became easier, while at the same time an accurate calculation of the breakdown voltage was achieved. A series of validations were performed, through the comparison with the already ex-isting, published and unpublished, experimental tests and a number of conclusions were listed. One of the most significant, was the specification of the correlation between the electrostatic model and test measurements and how these different approaches can be linked to each other in a practically efficient way. At the end, there is a proposal for further work on the subject, and possible improvements of the already conducted work. / Ökningen av spänningsnivåerna i kraftöverföringssystem har lett till högre kop-plingstransienter under drift. Konstruktionen av utrustning och nätverkskomponen-ter som kan motstå en sådan påkänning, kräver en noggrann förstudie av de elektriska fältet som genereras av dessa transienter. Ett gap av sfär-platta är den mest teoretiskt och praktiskt intressanta elektrodkon-figurationen att studera. Hittills har majoritetet av genomfört arbete avsett att studera urladdningsegenskaper för denna struktur. Dock krävs studie av elektrostatiska elek-triska fältet. En noggrann beräkning av elektriska fältet kan bidra till en ännu bättre förståelse för urladdningsegenskaper och principerna bakom dem. I detta projekt presenteras en simuleringsmetod för beräkning av elektrostatiska fäl-tet av en sfär-plan konfiguration, med varierande dimensioner av sfären och gapavstån-det. För detta ändamål har använts en Finite Element Method (FEM) lösning, där kon-figurationen utformades och problemets numeriska lösningen genomfördes. Därefter har gjorts ett försök för att ange genombrottsspänningen baserad på beräkning och distribution av elektriskta fältet. Resultat registrerades från både simulering av elektrostatiska modellen och beräkn-ing av genomslagsspänningen. Ett av de viktigaste resultaten var specifikationen av ett ungefärligt förhållande mellan diametrarna av sfären och röret där sfären är monterad. Som en konsekvens blev studiet av elektriska fältfördelningen lättare, medan en exakt beräkning av genomslagsspänningen uppnåddes. En valideringsserie har genomförts genom jämförelse med de redan existerande, publicerade och opublicerade, experimentella tester och ett antal slutsatser har noterats. En av de mest meningsfulla, var specifikation av sambandet mellan den elektrostatiska modellen och provmätningarna samt hur dessa olika tillvägagångssätt kan kopplas till varandra på ett praktiskt och effektivt sätt. Slutligen finns det ett förslag för fortsatta arbete samt eventuella förbättringar av redan genomfört arbete.

The main subject of the final thesis is to find a suitable method for measuring the partial discharge (PD) in the dielectric of high-voltage capacitor. In the theoretical part of my thesis contains from the mechanisms of origin and the harmful effects of partial discharge at high voltage insulation of capacitor. It describes the global galvanic method of partial discharge measurement, the principle of cascade voltage multiplier, its main components are high-voltage capacitor and diode, facilities quality measurement of capacitors for voltage multipliers, advantages and disadvantages and principles of HIPOTRONICS DDX-8003 with the pulse discrimination system. In the experimental part of the diploma thesis is familiar with the diagnostics of high – voltage capacitors by means of laboratory measurements on the electronic bridge and with the help of partial discharge measurement system. Design of suitable electrode arrangement is described which eliminates the influence of corona which makes it impossible to measure partial discharges and the dissipation factor (tg ). Analysis data from measurement and determination of quality level, eventual degradation of measured capacitors. The result of this project should be designed the methodology for finding of poor – quality capacitors in order to increase the reliability of the voltage multiplier.

The main subject of the final thesis is to find a suitable method for measuring the partial discharge (PD) in the dielectric of high-voltage capacitor. In the theoretical part of thesis contains from the mechanisms of origin and the harmful effects of partial discharge at high voltage insulation of capacitor. It describes the global galvanic method of partial discharge measurement, the principle of cascade voltage multiplier, its main components (high-voltage capacitor and diode). Nowadays are presented the possibilities of measuring the quality of capacitors for voltage multipliers. In the experimental part of the diploma thesis is familiar with the diagnostics of high – voltage capacitors by means of laboratory measurements on the electronic bridge and with the help of partial discharge measurement system. It describes the design of a suitable electrode arrangement that eliminates the influence of the corona, which makes it impossible to measure partial discharges and the dissipation factor tg . The thesis analyzes the obtained data from measurements and determines the quality level or the degradation of the measured capacitors. The result of the project should be designed the methodology for finding poor quality capacitors in order to increase the reliability of the voltage multiplier.