Diagnosis of Bearing Faults in Induction Machines by Vibration or Current Signals: A Critical Comparison

TLDR

Mechanical imbalances and bearing faults dominate machine failures, especially in small‑to‑medium sized units, making their diagnosis a heavily researched area with recent focus on current‑signal methods. The study compares vibration‑based and current‑based bearing fault detection, employing a simple signal‑processing method and theoretically linking torque disturbances to current components while reviewing existing fault models. The authors use a straightforward signal‑processing technique on both vibration and current data, theoretically relate torque disturbances to current amplitudes, and validate the approach by recreating realistic incipient faults experimentally. Experiments confirm the proposed method, showing that radial effects appear only with large failures causing air‑gap variations.

Abstract

Mechanical imbalances and bearing faults account for a large majority of the faults in a machine, particularly for small-medium size machines. Therefore, their diagnosis is an intensively investigated field of research. Recently, many research activities were focused on the diagnosis of bearing faults by current signals. This paper compares the bearing fault detection capability obtained with the vibration and current signals. The paper contribution is the use of a simple and effective signal processing technique for both current and vibration signals, and a theoretical analysis of the physical link between faults, modeled as a torque disturbance, and current components. The focus of the paper is on the theoretical development of the correlation between torque disturbances and the amplitude of the current components, together with a review of fault models used in the literature. Another contribution is the re-creation of realistic incipient faults and their experimental validation. Radial effects are visible only in case of large failures that result in air-gap variations. Experiments are reported that confirm the proposed approach.