High frequency behavior of AC machine: application of turn insulation aging diagnostic

The stator insulation breakdown is a major cause of AC machine failures. Ground insulation defaults are easily detected by classical systems based on the leakage current measurements, however the turn to turn insulation degradations are more difficult to detect. For large machines, on-line methods, based on partial discharge detection and analysis, give good results but they cannot be used for low-voltage machines fed by adjustable speed drives (ASD). This paper presents a new monitoring system able to detect slight variations of high frequency resonances in the winding of a working machine fed by an industrial inverter. The new system works in association with statistical data on the accelerated aging of the magnet wire