Measurements of physicochemical and electrical properties of insulating liquids

This paper provides a comparative analysis of key physicochemical and electrostatic parameters of Trafo En oil and Midel 7131® synthetic ester, changing in temperature and accelerated thermal ageing. The parameters tested included the density, kinematic viscosity, conductivity and relative electric permittivity. In addition to that, Electrostatic Charging Tendency (ECT) tests of those fluids were performed in a flow system using cellulose and aramid paper pipes. The effect of liquid flow velocity combined with temperature variations and accelerated ageing time on the streaming electrification current generated was determined. The relationship between the fluid electrification degree and measuring pipe material was also investigated.