Supply voltage level optimization in industrial low voltage networksVinnal, Toomas; Janson, Kuno; Kalda, Heljut; Sakkos, TiiuPQ2012 : 8th International Conference : 2012 Electric Power Quality and Supply Reliability : June 11-13, 2012, Tartu, Estonia : conference proceedings2012 / p. 149-154 : ill https://ieeexplore.ieee.org/document/6256219