9/19/2023 0 Comments Spectra on 7th![]() ![]() Traditionally a single xed frequency of the applied voltage is used for such measurements as in the Phase Resolved Partial Discharge Analysis (PRPDA) technique. Measurements of partial discharges are commonly used to diagnose the insulation system in high voltage components. , F3, Lindstedtsvägen 26, Stockholm, 13:15Ģ005 (English) Licentiate thesis, comprehensive summary (Other scientific) Abstract Other Electrical Engineering, Electronic Engineering, Information Engineering Trita-EE, ISSN 1653-5146 2008:018 Keywordspartial discharges, measurements, modelling, variable frequency, cavities, disc-shaped, polycarbonate This effect also contributes to the PD frequency dependence. The simulation results also show that certain cavity parameters, like the cavity surface conductivity and the rate of electron emission from the cavity surface, change with the time between consecutive PDs, and accordingly with the applied frequency. The PD frequency dependence is interpreted as a variation in influence on the PD activity from the statistical time lag of PD and the charge transport in the cavity surface, at different applied frequencies. The simulations show that essential features in the measured PD patterns can be reproduced. Moreover, the PD frequency dependence changes with the applied voltage amplitude, the size of the cavity and the location of the cavity (insulated or electrode bounded).Ī physical model is presented and used to dynamically simulate the sequence of PDs in the cavity at different applied frequencies. The PD phase and magnitude distributions, as well as the number of PDs per voltage cycle, change with the varying frequency. ![]() The measurements show that the PD process in the cavity is frequency dependent. The aim is to interpret the PD frequency dependence in terms of physical conditions at the cavity. In this thesis the PD process in a disc-shaped cavity is measured and modelled at variable frequency (0.01 - 100 Hz) of the applied voltage. With this technique, the frequency dependence of PD can be utilized to extract more information about the insulation defects than is possible from traditional PD measurements at a single applied frequency. The Variable Frequency Phase Resolved PD Analysis (VF-PRPDA) technique measures PD at variable frequency of the applied voltage. To diagnose the condition of high voltage insulation, PD measurements is commonly used. ![]() The presence of partial discharges (PD) in high voltage components is generally a sign of defects and degradation in the electrical insulation. Other Electrical Engineering, Electronic Engineering, Information Engineering Identifiers URN: urn:nbn:se:kth:diva-8457 DOI: 10.1109/ICPADM.2003.1218552 ISI: 000186114700209 ISBN: 0-7803-7725-7 (print) OAI: oai::kth-8457 DiVA, id: diva2:13786 Conference7th International Conference on Properties and Applications of Dielectric Materials, NAGOYA, JAPAN, JUN 01-05, 2003Ģ008 (English) Doctoral thesis, comprehensive summary (Other scientific) Abstract 839-842Ĭapacitance, Computer simulation, Electric conductivity, Electric fields, Electric impedance, Electric insulation, Electric network analysis, Electric variables measurement, Permittivity National Category Place, publisher, year, edition, pages2003. The results of simulations are compared with result of measurements on an asphalt-mica insulated machine stator bar. It is shown how the frequency dependence is influenced by the conductivity of the bulk insulation, the surface conductivity of the cavity walls and the statistical time lag. In this paper, simulations illuminate the frequency dependence of PD of a discharging cavity embedded in an otherwise homogeneous insulation. In this method the frequency of the applied voltage is variable and not fixed at the power frequency as in the standard PRPDA implementation. Variable Frequency Phase Resolved Partial Discharge Analysis (VF-PRPDA) is a newly developed method for partial discharge measurements. 839-842 Conference paper, Published paper (Refereed) Abstract 2003 (English) In: Proceedings of the 7th international conference on properties and applications of dielectric materials, 2003, p. ![]()
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