@inproceedings{HartmannHarrerDotterweichetal., author = {Hartmann, J{\"u}rgen and Harrer, S. and Dotterweich, C. and Zink, Markus H. and Hemberger, Frank and Ebert, Hans-Peter and Schnitzler, Tim}, title = {Phase change materials for use in thermally and electrically stressed insulation for high voltage applications}, series = {2016 IEEE Electrical Insulation Conference}, booktitle = {2016 IEEE Electrical Insulation Conference}, publisher = {IEEE}, isbn = {978-1-4673-8706-4}, pages = {605 -- 608}, abstract = {The temperature of high voltage equipment is often the limiting factor when transmitting electrical energy because the electrical insulation can get severely aged when the temperature is exceeding a certain limit. Hence, cooling has to be improved or heat generation must be reduced to avoid damage of the insulation. In this paper a new method was examined by investigating electrically insulating phase change materials which are able to store latent heat during a phase change from the solid to liquid state in times of high energy demand. To verify the electrically insulating properties of paraffins, one class of phase change materials, a special test cell was designed allowing the determination of breakdown voltage of phase change materials. The measurements on one paraffin sample proved the promising electrical insulating properties and it was shown that the breakdown voltage in the liquid state is comparable …}, language = {en} } @inproceedings{ZinkDotterweichHartmannetal., author = {Zink, Markus H. and Dotterweich, C. and Hartmann, J{\"u}rgen and Harrer, S. and Hemberger, F. and Ebert, Hans-Peter and Schnitzler, Tim}, title = {Phase Change Materials for Use in Thermally and Electrically Stressed Insulation for High Voltage Applications}, series = {IEEE Electrical Insulation Conference}, volume = {2016}, booktitle = {IEEE Electrical Insulation Conference}, pages = {605 -- 608}, language = {en} } @inproceedings{WirthReumannZinketal., author = {Wirth, Isabell and Reumann, Andreas and Zink, Markus H. and K{\"u}chler, Andreas and Langens, Achim and Schnitzler, Tim}, title = {Messung elektrischer und thermischer Transienten an Hochspannungsgleichstromdurchf{\"u}hrungen}, series = {Highvolt Kolloquium, Dresden, 2015 (Poster)}, booktitle = {Highvolt Kolloquium, Dresden, 2015 (Poster)}, language = {de} } @incollection{KuechlerWirthReumannetal., author = {K{\"u}chler, Andreas and Wirth, Isabell and Reumann, Andreas and Zink, Markus H. and Schnitzler, Tim and Langens, Achim and Berger, Frank}, title = {Steady-state and Transient Electrical Potential Distributions in HVDC Bushings Measured under Different Thermal Conditions}, series = {19th International Symposium on High Voltage Engineering}, booktitle = {19th International Symposium on High Voltage Engineering}, address = {Pilsen, Czech Repbulic}, abstract = {High voltage DC (HVDC) applications become more and more important and the voltage level for energy transportation increases steadily. Hence the design of the DC insulation systems becomes more and more difficult. The difference between HVDC and HVAC insulation systems is that in HVAC the electrical field is distributed according to the permittivities of the materials. Permittivity is only weakly dependent on temperature, so there is no significant difference between the electrical field distribution at room temperature and operating temperature of the insulation system. In HVDC however the electrical field is distributed according to the conductivities of the insulation materials whereas the conductivity is strongly dependent on temperature. This can lead to completely different field distributions at varying temperatures. The investigations presented here show simulation results of HVDC bushing cores in comparison with measurements on those test objects. Simulations and measurements were performed both for temperature distributions and electric potentials of the grading layers in the bushing at DC voltage. For the first time, it was shown by experiment that the FEM simulation can reproduce real DC field distributions very well. It was also shown, that there is a strong influence of temperature gradients or temperature transients on transient and steady-state electrical potential distribution inside the insulation.}, language = {en} } @inproceedings{WirthReumannKuechleretal., author = {Wirth, Isabell and Reumann, Andreas and K{\"u}chler, Andreas and Schnitzler, Tim and Langens, Achim and Berger, Frank and Zink, Markus H.}, title = {Steady-state and Transient Electrical Potential Distribution in HVDC Bushings Measured under Different Thermal Conditions}, series = {19th International Symposium on High Voltage Engineering}, booktitle = {19th International Symposium on High Voltage Engineering}, address = {Pilsen, Czech Republic}, language = {en} } @inproceedings{WirthSturmKuechleretal., author = {Wirth, Isabell and Sturm, Sebastian and K{\"u}chler, Andreas and Zink, Markus H. and Berger, Frank and Schnitzler, Tim}, title = {Ber{\"u}cksichtigung von Leitungs- und Polarisationsmechanismen in transienten FEM-Simulationen von HG{\"U}-Isoliersystemen}, series = {VDE-Hochspannungstechnik 2018, Berlin}, booktitle = {VDE-Hochspannungstechnik 2018, Berlin}, abstract = {The calculation of electrical field distributions in insulation systems for high voltage direct current (HVDC) transmission using the finite element method (FEM) usually only considers the dielectric properties in the form of permittivities and conductivities. Due to not sufficiently well simulated transient processes, state of the art is considering the polarization processes by equivalent network models. The application and implementation of polarization mechanisms in a FEM soft- ware closes this gap and allows calculating the electric field distribution more precisely. An implementation of additional differential equations, according to the RC-network model, describing the field dependent polarization mechanisms, are complementing the displacement and conduction current. Material equations and their parameters are determined by measuring the polarization and depolarization currents (PDC). These equations are necessary for both the RC-network models and the differential equations for the FEM. They can be adapted to the actual temperatures in the insulation system. Hence, the necessarily multidimensional electric field calculations of complex insulation systems with stationary or transient temperature-gradients are possible. The described calculation method is verified by reactionless fieldmill voltmeter measurements of transient voltage profiles at the grading foils of modified high voltage DC-bushings. A better accuracy is achieved for the simulation of transient and stationary potential distributions.}, language = {de} } @inproceedings{WirthReumannKuechleretal., author = {Wirth, Isabell and Reumann, Andreas and K{\"u}chler, Andreas and Zink, Markus H. and Berger, Frank and Langens, Achim and Schnitzler, Tim and Heil, B.}, title = {Measurement and simulation of transient field stresses and impacts on advanced insulation design and new test procedures for HVDC components}, series = {Cigre-Konferenz, Paris}, booktitle = {Cigre-Konferenz, Paris}, language = {en} }