Effective Selection of a Dielectric Health Index for Diagnosis of Electric Motors

The development of proper condition monitoring routines is essential for the secure and reliable operation of industrial induction motors, either low or medium voltage motors. In an induction motor, is possible to develop a series of testing to evaluate the condition of its insulation system. The insulation system of an induction motor is subjected to various stresses, which degrades their characteristics day. Therefore, monitoring their condition is key to guide decision making by those in charge of their operation. In this work, a new methodology for evaluate the condition of the insulation system of induction motors based in a health index is proposed. This proposal uses a health index based on a classic method of construction, combining expert criteria with a validation using real data of motors repaired. Several study cases are required to adjust the parameters used to calculate the health index. Once the parameters of the health index are adjusted, the operating condition of several induction motors are established to test the effectiveness of the proposed tool. The results show a good performance evaluating induction motors repaired in an electric motor workshop that participated in this work. This also indicates that moving towards the use of a health index for evaluate induction motors might enhance the behavior (reliability) of an industrial plant (as a whole).