A comparison of online PD measurement systems applied to gas compression plant motors

There are a number of competing online partial discharge (PD) measurement systems available in the marketplace today. Since most of these systems utilize procedures and equipment that differ from one another, it has been difficult to compare the results between the varying systems and difficult to provide guidelines that apply to all. To undertake a comparison of several competing systems it was necessary to apply the instruments on the same machines, at the same time, using a baseline sensor system that all vendors agreed to work with. This paper summarizes the results of the comparison, provides objective insight into the similarities of and the differences between the three vendors, and introduces a scaling F factor that allows for normalization of PD data measured in different units. Although this paper comments on the inconsistency found in some PD data with respect to loading and temperature rise, its primary focus is the consistency between PD data taken with a variety of competing equipment.