State diagnosis device, state diagnosis method, and abnormality sign inference device of electric motor

A state diagnosis device for an electric motor, comprising:

• a current input circuitry which receives current data detected from the electric motor by a current detector;
• an analysis circuitry which performs frequency analysis on the current data received from the current input circuitry, to calculate an analysis result;
• a calculation circuitry which detects a plurality of peak intensities of sideband waves about a power supply frequency of the electric motor, from the analysis result;
• a characteristic peak extraction circuitry which calculates a natural frequency of a belt gear portion from rating information of the electric motor, and extracts, from the plurality of peak intensities detected by the calculation circuitry, the peak intensity of the sideband wave appearing at a position away by a distance of the natural frequency from the power supply frequency of the electric motor as a reference;
• and
• a judgment circuitry which compares the peak intensity extracted by the characteristic peak extraction circuitry with a peak intensity threshold calculated from the electric motor operating normally, to perform diagnosis for the electric motor.