Ageing Indicators of Stator Winding Insulation subjected to Elevated Frequency Voltage Thermal Stresses

摘要

Laboratory studies were carried out to identify ageing indicators of stator winding insulation during ageing under elevated frequency, voltage and thermal stresses. A group of six generator bars was subjected to either electrical, thermal and combined electrical-thermal stresses. Electric stresses of 5kV/mm, 915 Hz and 6 kV/mm, 915 Hz and thermal stresses 170°C, 180°C and 200°C were chosen for the ageing studies. Combined electrical-thermal ageing studies were conducted at 5kV/mm, 915 Hz and 100°C. Evaluation study was conducted by electrical, thermo-analytical and spectroscopic techniques. The results are presented and discussed in this paper.