A Power Quality problem is defined as a problem that results in voltage, current, or frequency deviations and subsequently in failure, misoperation or premature aging of customer's equipment. However, beside these consequences, reduced Power Quality also leads to additional losses in the power system. Three phenomena that lead to additional losses, namely Harmonic Distortion, Unbalance and low Power Factor, are presented in this paper and a method for calculating the losses that they cause in the various parts of a typical industrial installation, such as transformers and cables, are analyzed. Additionally, a classification method for these losses is proposed. The goal was to create a classification method which could be implemented in an i...