Enhancing Motor Reliability for Thermal and Environmental Stresses

Induction motors require robustness and the ability to withstand environmental factors in the application. One of these factors can be the presence of humidity, which directly affects the performance of the insulation systems. In the context of insulation systems, the impregnation aims to provide greater dielectric and mechanical rigidity to the winding, as well as to act as a barrier to the external environment, thus enabling resistance to potential increases in humidity due to the application. To evaluate the effectiveness of the different impregnation system that can be part of the Electric Insulation System, in this work were developed two cycles of testing with different conditions in four different types of impregnations. To consider the high humidity of application, initially, the samples were placed in a wet chamber with 95% relative humidity and a temperature of 40 degrees C, where the behavior of insulation resistance over 500 hours was assessed. In a second phase, the motorettes were subjected to thermal aging campaign, and the behavior of the Partial Discharge Inception Voltage (PDIV) of the samples was evaluated until failure. The thermal cycles started at 180 degrees C, and each cycle lasted for 500 hours, with an increase of 20 degrees C in each cycle. Additionally, the PDIV of the samples was monitored, and its decay over time was recorded. The experimental results indicate that the impregnation method has a significant impact on the useful life of the samples, in addition to allowing the observation of a decline in insulation resistance in cycle 1 and a decline in PDIV values over time before failure in the cycle 2.