Motor Stator Windings On-site Assessment Challenges and Recommendations for Reliability and Condition Monitoring

Large machines stator winding diagnostic testing performed during on-site assessment can pose different types of challenges compared to tests that are performed during factory acceptance tests (FAT). These challenges can be associated to limitations of test instrumentation, complex site set-up, environmental and/or site conditions, access to certain machines component and other parts that might influence the final results. Determining reliability and condition of the machine on-site is a critical element of machine operation for end-users which is done through several tests defined in relevant Industry standards. However, some of these tests are suited more for in factory setup rather than for in-situ. Advancement of testing methods and instrumentation over recent years has reduced difficulty to carry out in-situ testing e.g. EL-CD) for detection of imperfection in stator cores, compact design DC hi-potential set, portable inter-turn surge tester and VLF hipot equipment. In this paper, based on years of exposure and insight obtained, critical gaps in the Industry standards have been discussed along with the recommendations. Reliable machine operation and its condition assessment is a crucial element to avoid unnecessary outages.