A practical experimental method with high accuracy for research of thermal aging properties in winding insulating systems

Summary form only given. In the research of thermal stress performance as well as aging phenomena and properties of insulating materials and systems for electrical machine the controlling accuracy of the thermal stress intensity (the aging temperature) exercises immediately an influence on the precision of the researching results. Such as the statements in another paper, some deviation and error that occurred in the conclusion of many aging tests and studies were just caused by the inaccurate control of thermal stress intensity. A practical experimental method with high accuracy and reliability for research of thermal aging properties in winding insulating systems has been developed in this works in consideration of the distinction between thermal aging and thermal breakdown in the thermal aging process. By means of this method the aging phenomena and performance of the tested winding insulating systems can be accurately observed, measured, and analyzed in various aging phases or periods, so that these experimental data will provide reliable scientific basis not only for the improvement, of the insulating systems design but also for the fault detection and fault prognosis in the applications. There are many experimental techniques, which are used in this method, such as SPS, sensor-technique, signal-feedback-control, reverse-driving, PC-monitoring, EDP system and etc. The test winding insulating systems aged practically at the complete stresses that include the accurate control of thermal stresses (deviations: ±1°C) in a specially developed driving-stand. The experimental results provided with lots of reliable and accurate data for research of thermal aging properties in winding insulating systems and verified the necessity of the distinction between thermal aging and thermal breakdown in the meantime