Controlled addition of spherical metallic nanofillers below the percolation threshold has shown improved interfacial properties in mitigating the space charge accumulation over the base epoxy polymer material The theoretical model is utilized in the present study to elucidate the variation in an interfacial area with the addition of aluminium nanoparticles. It results in the inclusion of nanoflller until a particular filler concentration has shown an increase in the interfacial volume. In contrast, reduction in inter particle distance with the further addition of nanoparticles has shown the reduced interfacial volume. Since the space charge information in a given material is unique at a given instant of time within the bufk, a classification technique, Le. principal component analysis is employed in classifying the nanocomposite materials having different filler concentrations. © 2020 Institute of Electrical Engineers of Japan. All rights reserved.