A New Method for AC Machine Turn Insulation Diagnostic Based on High Frequency Resonances

Abstract

International audienceThe stator insulation breakdown is a major cause of AC machine failures. Ground insulation defaults are easily detected by classical systems based on 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 accelerated aging of the magnet wire used to build the machin

Wide frequency range analysis of the electromagnetic emissions of electrical machine for diagnosis

“…A HF lumped parameter model of the machine winding shows that the turn-to-turn capacitance variation have a significant impact on the winding HF resonances [12].…”

“…A detailed study of the HF behaviour of the motor winding show that the lower part of the HF impedance spectrum can be modeled by a RLC parallel equivalent circuit [12]. The inductance of this equivalent circuit depends on leakage flux in the machine, the resistance on HF losses and the capacitance is strongly linked to the winding turn-to-turn ones.…”

Evaluation and current-response based identification of insulation degradation for high utilized electrical machines in railway application

“…The results show that one reliable parameter for the estimation of insulation degradation is the measured capacitance. According to [7] changes of the turn-turn capacitances resulting from stress through thermal cycling is detectable. The insulation degradation process is usually slowly developing, first starting with the deterioration of the turn-turn insulation and finally leading to higher severity faults like phase to phase or phase to ground, respectively until a breakdown of the insulation.…”

Detecting turn insulation failures in motor coils using ground current signals

“…PD measured on-line or off-line is widely used to detect turn-to-turn insulation damage for relatively large motors [5][6]. Recently, a new method based on the indirect measurement of the turn-to-turn capacitance of stator windings was proposed [7]. It was found that winding turn-toturn capacitance increases with insulation aging.…”