Space charge behaviour in an epoxy resin: the influence of fillers, temperature and electrode material
Résumé
This study has the aim to characterize the behaviour of the space charge in an epoxy resin used as electrical insulation in systems such as transformers and bus bars. Temperature, field level, filler content and nature of the electrodes are the parameters that were considered. Space charge measurements were performed using the Pulsed Electro Acoustic technique (PEA), in a range of field and temperature up to 40kV/mm and 72°C, respectively, on gold-coated and uncoated samples. We discuss the possibility of performing space charge measurement on filled epoxy resin despite the piezoelectricity of quartz fillers. Under DC field we observed a quasi-symmetrical build-up of homocharges at both electrodes, followed by a substitution of the homocharges by heterocharges, mainly close to the cathode. In addition, we recorded the space charge behaviour just before breakdown on filled sample at 72°C under 12kV/mm
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