Synergistic Effect of Epoxy Resin Dielectric Properties Deterioration Under the Action of High-frequency Square Wave Electric Field-temperature Field
The epoxy resin sealing insulation in high-frequency transformers has been exposed to prolonged high-frequency square wave voltage stress and thermal stress.The deterioration of the insulation performance within the epoxy resin under these conditions significantly hampers the operational reliability of the transformers.Previous studies primarily focused on analyzing the dielectric properties of epoxy resins under alternating current sinusoidal electric fields and temperature fields,however,the studies on the change of dielectric properties of epoxy resin under the action of high-frequency square-wave electric field and temperature field are rarely available in the literature.In this paper,a high-frequency square-wave voltage and temperature joint aging experimental platform is set up to study the dielectric properties of epoxy resin samples under different aging electric field strengths and temperatures,and the results of the combined electro-thermal aging are compared with the results of the separate thermal aging and electric aging.The ex-perimental results show that the effect of electro-thermal joint aging on the dielectric properties of epoxy resin is more significant and greater than the superimposed effect of electricity and heat,indicating there is a synergistic effect in the process of electro-thermal joint aging.By constructing the polarization loss simulation model of epoxy resin under high-frequency square-wave voltage,it is clarified that the temperature increase of the sample caused by the polarization loss of epoxy resin under the action of high-frequency square-wave electric field is an important reason to aggravate the deterioration of the dielectric properties of epoxy resin.The results of this study can provide a reference for the evaluation of the insulation state of high-frequency transformers.
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