Advances in diagnosis of electrical machines through external magnetic field

Promising parameter in the analysis and diagnosis of electrical machines is the external magnetic field that can be measured in the vicinity of the machine. This variable provides an image of the internal magnetic state of the machine and it is sensitive to very small imbalances in the machine. Therefore, information about the presence of an anomaly can be found in the analysis of this field. The magnetic field is measured close to the machine by specific wound flux sensor and is analyzed considering the evolution of its spectral content in presence of stator or rotor electrical faults. The paper gives an overview of measurement methods, fault signatures, and analysis tendency in the diagnosis of rotating electrical machines using the measurement of the external magnetic field.