Application of the method of monitoring partial discharges in insulation of high-voltage electrical machine stators

Many processes in electric isolation are caused by features of its structure - manifestation of polarization and redistribution of electric field. Differences in dielectric properties (dielectric permittivity) of isolation cause redistribution of electric field and formation of sections of isolation with the increased electric field intensity. In use there is deterioration in properties of isolation and its destruction under the influence of electric field, temperature, moistening, vibration, and so on. Transneft Electric Network Service, LLC in 2018 performed works on diagnostics of Siemens high-voltage electric motors of trunk pumping units with a power of 6300 and 8000 kW in the Transneft Far East, LLC facilities by a control method of partial discharges in isolation of stators of high-voltage machines. In this article the issues of selecting diagnostic equipment, as well as frequency range for registration of partial discharges are considered. The main areas of localization of insulation defects of the stator winding of an electric machine are determined. Also the article presents results of approbation of a test procedure for electric motor winding insulation by measuring partial discharges.