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Electrical energy networks' reliability is driven by both, the quality and the reliability of its electrical equipment, e.g. power transformers. Local failures inside their oil/paper insulation can cause breakdowns and resulting high outage and penalty costs. Power transformers are tested on partial discharge (PD) activity at a factory routine test. Complementary, UHF PD monitoring can be used to...
We present EMI simulations of a silicon carbide MOSFET traction inverter. The simulations are based on a transient circuit simulation and frequency domain simulations of different 3D geometry models. In a first step, an equivalent circuit is derived from parts of the geometry model and combined with an analytical model of the MOSFETs and an equivalent circuit model of the DC link capacitor. The results...
This contribution investigates behavioral MOSFET models used for the simulation of conducted and radiated electromagnetic interferences (EMI) of an automotive inverter. A combined simulation of an equivalent circuit and the 3D geometry for a traction inverter based on 1.2 kV, 40 A SiC MOSFETs is presented. The model considers the MOSFET as a combination of parasitic elements of the package, voltage-dependent...
The paper presents a long-term monitoring example of an aged generator step-up transformer with several PD sources showing different activity. Monitoring data is recorded by the use of the electromagnetic PD measurement method, also known as the UHF-method. The phase resolved PD patterns of collected UHF measuring data are analyzed using cross-correlation. The method searches for characteristics of...
This paper discusses the use of vibrations for power transformer surveillance. Therefore, basic research of transformer vibration is presented including the physical background of vibrations and methods of measurement in terms of sensor techniques comparing in-oil and outside tank wall measurement. A case study of an outside tank wall measurement performed on an aged generator step-up transformer...
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