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Brytspänningen är den spänning som uppkommer när överkopplingsmotståndet i lindningskopplaren lämnar sitt föregående läge vid omkoppling. Storleken på brytspänningen i lindningskopplaren beror på hur stor läckinduktansen är. Är den inte känd så kan brytspänningen istället beräknas med hjälp av FEM-programmet ACE (internt ABB-program) i samband med Mathcad. I ACE beräknas först reaktanserna i p.u-enheter mellan lindningarna och hur stora de är beror på lindningslayouten. Det är tidskrävande att använda ACE och Mathcad och uppgiften är att utreda de parametrar som påverkar storleken på brytspänningen samt att ta fram en förenklad beräkning av densamma. Genom simulering i ACE av en mängd olika lindningslayouter visar det sig snart att det är alltför många parametrar som påverkar reaktanserna. De förenklingar som trots det har tagits fram är lite för grova för att det ska vara pålitligt. Mathcad är än mer komplext med tunga beräkningar som inte är lätta att förenkla. Arbetet har ändå gett mer kunskap om hur reaktanserna påverkas av geometrierna i lindningarna och kommer att vara till viss nytta, även om det inte gick att förenkla ACE- och Mathcadberäkningarna så som var tänkt. / The recovery voltage is the voltage that occur when the transition resistor in the tap-changer leaves its previous position during an operation cycle. The amplitude of the recovery voltage depends on the leakage inductance. If the leakage inductance is unknown, the recovery voltage can instead be calculated using a FEM-program called ACE (internal ABB-program) in conjunction with Mathcad. First, the reactances between the windings are calculated in per unit (p.u) using ACE and they depend on the winding layout. It is time consuming to use ACE and Mathcad and the task has been to investigate the parameters that affects the recovery voltage and to develop a simplified calculation of it. Through simulation using ACE of a number of different winding layouts one soon comes to the conclusion that there are simply too many parameters affecting the reactances. Although the simplified calculations that despite this has been developed, they soon prove to be too rough to be useful. Mathcad is even more complex with heavy calculations that are not easy to grasp. However, this thesis has given more knowledge about the way the reactances are affected by the geometry of the windings, even though it was not possible to in a reasonable way simplify the calculation of ACE and Mathcad.

Esta dissertação aborda o cálculo da taxa de crescimento da tensão de restabelecimento transitória (TCTRT), considerando o caso de falha na barra, durante a abertura do primeiro polo e o cálculo da tensão de restabelecimento transitória (TRT) nos primeiros instantes de tempo, incluindo o efeito da capacitância. Os principais casos possíveis de falha na barra foram analisados e os resultados demonstraram a precisão das expressões obtidas. Normalmente, o cálculo da TCTRT e da TRT é feito por meio de simulações em programas de transitórios eletromagnéticos em que há rotinas específicas para a extração dos valores destas, porém, em determinadas condições, podem ocorrer oscilações ou imprecisões numéricas. Por ser um assunto de grande interesse convém desenvolver expressões que possam esclarecer resultados duvidosos sem a necessidade de artifícios de redução do passo de integração a valores muitas vezes não factíveis. As expressões obtidas neste trabalho podem ser utilizadas não só para se obter de forma precisa e simplificada os valores da taxa de crescimento da tensão de restabelecimento transitória de um circuito real, assim como os valores da TRT nos primeiros instantes de tempo. / This study is focused on the rate of rise of transient recovery voltage (RRTRV) calculation considering the case of bus fault, during the first pole to open, and also includes the transient recovery voltage (TRV) calculation, in the first instants of time, including the capacitance effect. The main cases of bus fault have been evaluated and demonstrate that the expressions developed in this study are relevant and with good precision. Usually, the RRTRV and the TRV are calculated with the use of simulation programs, using specific routines, nevertheless, in certain conditions, there might be oscillations and numeric imprecisions which requires a mathematic expression. This topic is of great interest and it is important to have mathematical expressions that could clarify doubtful results. The expressions obtained in this study can be use in a very simples and effective mode to calculate RRTRV and the TRV in the first instants of time, considering a real life circuit.

Esta dissertação aborda o cálculo da taxa de crescimento da tensão de restabelecimento transitória (TCTRT), considerando o caso de falha na barra, durante a abertura do primeiro polo e o cálculo da tensão de restabelecimento transitória (TRT) nos primeiros instantes de tempo, incluindo o efeito da capacitância. Os principais casos possíveis de falha na barra foram analisados e os resultados demonstraram a precisão das expressões obtidas. Normalmente, o cálculo da TCTRT e da TRT é feito por meio de simulações em programas de transitórios eletromagnéticos em que há rotinas específicas para a extração dos valores destas, porém, em determinadas condições, podem ocorrer oscilações ou imprecisões numéricas. Por ser um assunto de grande interesse convém desenvolver expressões que possam esclarecer resultados duvidosos sem a necessidade de artifícios de redução do passo de integração a valores muitas vezes não factíveis. As expressões obtidas neste trabalho podem ser utilizadas não só para se obter de forma precisa e simplificada os valores da taxa de crescimento da tensão de restabelecimento transitória de um circuito real, assim como os valores da TRT nos primeiros instantes de tempo. / This study is focused on the rate of rise of transient recovery voltage (RRTRV) calculation considering the case of bus fault, during the first pole to open, and also includes the transient recovery voltage (TRV) calculation, in the first instants of time, including the capacitance effect. The main cases of bus fault have been evaluated and demonstrate that the expressions developed in this study are relevant and with good precision. Usually, the RRTRV and the TRV are calculated with the use of simulation programs, using specific routines, nevertheless, in certain conditions, there might be oscillations and numeric imprecisions which requires a mathematic expression. This topic is of great interest and it is important to have mathematical expressions that could clarify doubtful results. The expressions obtained in this study can be use in a very simples and effective mode to calculate RRTRV and the TRV in the first instants of time, considering a real life circuit.

Transient Recovery Voltage (TRV) is an important consideration in the selection and installation of circuit breakers with appropriate ratings. Capacitor banks with inrush current limiting reactors are an integral part of the power system. Capacitor banks with inrush reactors on the load side terminal of the capacitor breaker alter the TRV seen across the breaker and it is critical to carry out the TRV analysis to prevent circuit breaker failure. TRV analysis has been performed for various capacitor bank - inrush reactor configurations, with the fault occurring at different terminals on the load side. Analytical solutions have been presented for both single-phase and three-phase ungrounded capacitor banks. Neutral displacement voltage of three-phase ungrounded capacitor banks result in increased stress across the breaker. Results have been validated with PSCAD simulation and MATLAB plots. / text

The present thesis attempts at an overview of DC methods used for diagnosing electrical isolation systems. It investigates the problem of small currents and how to measure them. Part of the thesis deals with building a workstation designed for long-term monitoring of absorbing characteristics of dielectric materials and it also presents a layout of a workstation used for measuring recovery voltage. Both workplaces are computer-automated using the VEE Pro application provided by Hewlett-Packard. Tests were performed on both workstations and the obtained results were processed in a test report as specified under ČSN IEC 93. During the experiment, every effort was made to ensure and monitor the atmospheric conditions of the measuring process.

[pt] O trabalho desenvolvido estabelece uma metodologia de estudo para a determinação dos requisitos de tensão de restabelecimento transitória de disjuntores através de simulações em computador digital com a utilização do programa de cálculo de transitórios elétricos Electromagnetic Transients Program (EMTP) de Bonneville Power Administration (BPA). / [en] It is established in this paper a study method to determine the transient recovery voltage requirements for circuit breakers, by means of simulations in digital computer, using the Electromagnetic Transients Program (EMTP) de Bonneville Power Administration (BPA).

No description available.

In this work describe to the Dielectric relaxation spectroscopy for the evaluation of the actual status of insulation systém. The used methods of quantifying the dielectric response in time domain are polarization-depolarization current and recovery voltage measurement and in frequency domain the loss factor and the complex capacitance measurement. Influence of thermal ageing and temperature dependences of charge and dischage currents are observed.