A method of diagnostics of induction-motor rotor eccentricity

Electroenergetics and industry mainly use induction motors (IMs) as drives of mechanisms. One method to improve their operational reliability and service life is effective and timely diagnosis of abnormal operating modes, in particular, rotor eccentricity. However, for a number of reasons, it has not before been possible to develop a diagnostic system that would allow one to effectively identify the rotor static eccentricity during an operational process. To solve this problem, a method of diagnostics of rotor eccentricity in IM has been proposed that uses a stator current, and the amount of eccentricity is determined by the operative value of additional current. It is proposed to carry out IM diagnostics in an idling regime in two stages. At the first stage, the reference values of a harmonics of stator current’s components of additional current, its operative value, and dependence from the rotor eccentricity are determined and saved for a fully functioning machine. At the second stage, the values of a harmonics of stator current’s and components of additional current are determined. The operative value of additional current iscalculated taking into account the relation of the received harmonics to their reference value, and the shift of a rotor is determined by reference dependence. © A.N. Novozhilov, E.V. Kryukova, T.A. Novozhilov, 2014.