Insulation in rotating machines is a common cause for failure. Therefore, it is important to further increase the knowledge of the phenomena related to insulation degradation. Today, there are many different methods of detecting Partial Discharge (PD) in stator bar insulation and this study aims to perform a selected variety of commonly used methods for comparison and to further enhance the current knowledge on the matter. 20 stator bars from a hydro generator, that was being taken out of operation due to insulation problems, were obtained for this study. The following measurements were performed on the bars: electrical phase resolved partial discharge analysis, acoustic partial discharge measurements, and breakdown testing. An attempt was made to locate the partial discharge source within the stator bars as well as to identify the different types of partial discharges observed from the measurements. It was found that the stator bars had a significant amount of partial discharge within them and that most of the worst cases could likely be due to the stress grading of the bars. The comparison of electrical partial discharge analysis and acoustic partial discharge analysis showed that in this case the two methods complimented each other, where the electrical method provided more detailed results for deeper analysis. Furthermore, the attempt to perform breakdown tests showed that despite the large amount of partial discharges in the bars, most of the bars were in no danger of breaking down due to electrical stress had they been kept in operation.