TY - JOUR N2 - Varying ohmic loss in the winding of electrical machines, which are operated at various operating points, results in temperature changes during operation. Particularly, when the temperature is varying dynamically, the insulation system suffers from repeated thermalmechanical stress, since the thermal expansion coefficients of the insulating materials and copper conductors are different. For the appropriate design of an insulation system, the effect of thermal-mechanical stress must be known. In the present work, motorettes are subjected to repeated thermal cycles. The expected lifetime is estimated and compared to the lifetime which is achieved by applying a lifetime-model which only considers thermal aging while ignoring thermal-mechanical stress effects. In addition, the hotspot temperature is simulated, the lifetime at the hotspot is estimated as theworst case. As expected, the results indicate that the thermal-mechanical stress plays a significant role during dynamic thermal aging of the winding insulation system. To better understand the thermal-mechanical stress effect, the resulting thermal-mechanical stress in a single wire is analyzed by the finite element method. A preliminary analysis of the aging mechanism of materials due to cyclic thermal-mechanical stress is performed with the theory of material fatigue. L1 - http://www.czasopisma.pan.pl/Content/118980/PDF/art16.pdf L2 - http://www.czasopisma.pan.pl/Content/118980 PY - 2021 IS - No 1 EP - 244 DO - 10.24425/aee.2021.136064 KW - hotspot KW - insulation system KW - material fatigue KW - thermal-mechanical stress A1 - Yang, Liguo A1 - Pauli, Florian A1 - Hameyer, Kay PB - Polish Academy of Sciences VL - vol. 70 DA - 2021.03.25 T1 - Influence of thermal-mechanical stress on the insulation system of a low voltage electrical machine SP - 233 UR - http://www.czasopisma.pan.pl/dlibra/publication/edition/118980 T2 - Archives of Electrical Engineering ER -