Continuous partial discharge analysis during automated thermal cycle aging experiment

This work presents an experiment proposal for continuous partial discharge analysis during an automated thermal cycle experiment for hydro generator stator coils/bars. It is an innovative approach because we propose to perform partial discharges test and thermal cycle experiment simultaneously, while they are usually performed individually. We developed an automated test bench that allows performing data acquisition throughout the experiments. We decided to force different coil failures during the tests to observe any changes in the partial discharges trend. First, we changed the thermal cycle temperature limits, and this led to coil overheating before an electrical failure occurred in the insulation. Later, we applied a voltage that was higher than the rated for the coil, which led to a faster electrical failure. The partial discharges trend changed moments before the electrical fault, and the system was able to identify such change. Our preliminary results show that the continuous analysis of partial discharges trends might lead to better maintenance planning by identifying the moment when the hydro generator aging gets critical.