| This study has the aim of characterizing the behaviour of the space charge in an epoxy resin used as electrical insulation in systems such as transformers and bus bars, using films as laboratory specimen. Temperature, field level and nature of the electrodes are the physical parameters on which we have acted. A spatio-temporal measurement technique of space charge, known as Pulsed Electro Acoustic (PEA) method, and external current measurements were implemented in thermalized environment, under DC field up to 40kV/mm. We observed chronologically a quasi-symmetrical build-up of homocharges, then a substitution of heterocharges, more importantly close to the cathode. These phenomena are discussed in the light of the measured external currents and of the quantitative differences which appeared depending on material, temperature and nature of the interface considered |
