Motor insulation condition assessment using expert systems software

An expert system has been developed which helps maintenance personnel diagnose the condition of rotor and stator windings in motors and turbine generators rated 2300 V and above. The expert system, called MICAA, uses an approach which has been found to be effective for diagnosing medical problems, and which has proven to be a much better medium than a printed handbook for diagnostic applications. The user interacts with the program to input machine nameplate information, operating status, and any past test data that is available. In addition, the program suggests tests which may be useful, as well as guiding maintenance personnel on what to look for in visual inspections of the machine. The expert system stores and correlates all this information, calculates the overall condition of both the stator and rotor windings, and identifies the most likely specific causes of any deterioration. The latter is very useful for determining what maintenance or operating changes are needed to extend winding life. In addition to its diagnostic capability, the program´s comprehensive technical help and the ability to store test data in a permanent database have also been of benefit to users. The expert system is now being used by over 200 maintenance personnel primarily in power utility companies in the United States. This paper first describes the reason for the development of an expert system in this area, and then describes its application as a preventive maintenance tool for motor and generator condition assessment