Space charge measurements on filled epoxy

The effects fillers can have on the space charge measurement are discussed. A review of the influence of particle piezoelectricity, permittivity, electrostrictivity and expansivity, on the space charge signal is presented. A silica filled epoxy resin is analysed using the light-induced-pressure-pulse (LIPP) method. A spurious signal is measured and is shown to be due to the piezoelectric effect of the silica filler particles. Finally, space charges are detected at the epoxy/silica interfaces, after poling for 2 hours at 10 kV/mm.