The Impact of Inertia on Rotor Fault Effects—Theoretical Aspects of the ViennaMonitoring Method

This paper investigates the impact of inertia on the fault signatures of squirrel cage induction machines. Rotor faults give rise to harmonic sideband currents and double slip frequency shaft torque oscillations, however. The total drive inertia thus influences the speed ripple which, again, influences the balance of the magnitudes of the lower and upper sideband current. Considering certain assumptions, the impact of the speed ripple on the current harmonics with respect to the stator and rotor fixed reference frame is investigated analytically. Additionally, the derived equations are applied to the Vienna Monitoring Method, a model-based rotor fault detection method.