Stator insulation system evaluation and improvement for medium voltage adjustable speed drive applications

In the last decade, industries have refined motor insulation systems to be more suitable for low voltage (LV) adjustable speed drive (ASD) applications. Furthermore, recent advances in power electronics and control systems have significantly increased the use of medium voltage (MV) ASD on motors. However, the challenge for reliability and service life has become more critical since many MV ASD fed motor systems are often associated with much larger and more critical process controls as compared with LV ASD fed motor systems. Thus far, only limited research has been conducted to evaluate and further develop medium voltage ASD fed motor insulation systems. IEC TC 2 WG 27 experts have spent nearly 5 years developing guidelines for qualifying insulation systems that are used for ASD fed motors (IEC TC 60034-18-42). To support the frame work of this technical guideline development, a series of research studies have been conducted. In this report, partial results of these studies will be presented. The focus of this research was to evaluate the impacts of MV ASD on all insulation components in motor stator windings. Information gathered by this project provides a better understanding of the aging processes generated from MV drives on the insulation system, and helps with the improvement of insulation system designs.