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
This paper focus on the prevention and risk management of DC arcs in batteries. Indeed some commercial Liion batteries include Positive Temperature Coefficient (PTC) and Current Interrupt Device (CID) to manage safety concerns. PTC is used to prevent too high currents inside the cell. CID is used to manage cell over-charge by opening the cell circuitry by internal pressure increase. Analysis will be used to improve the Li-ion batteries safety in high voltage applications. The experimental test bench is composed of a 48 V DC battery pack and a variable resistor which can deliver a continuous current up to 1000 A. Two configurations are considered to initiate the arc. In the first configuration, the CID opens dynamically by contact release. The second configuration consists in igniting an arc between the electrodes with a copper wire in a confined space. Arc voltage and current are measured. Arc image is recorded using a high speed video camera which allows an analysis of the physical phenomena. Arcing analysis leads to solution proposal to reduce arcing risk.
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