It has long been known that comparing the partial discharge results obtained from a single machine is a valuable tool enabling companies to observe the gradual deterioration of a machine stator winding and thus plan appropriate maintenance for the machine . In 1998, at the annual Iris Rotating Machines Conference (IRMC), a paper was presented that compared thousands of partial discharge (PD) test results to establish the criteria for comparing results from different machines and the expected PD levels . At subsequent annual Iris conferences, using similar analytical procedures, papers were presented that supported and expanded upon the previous criteria [6 – 21]. This paper presents the most recent statistical analysis of the database.
Previous database analyses have only separated results based on voltage class, sensor type and cooling gas pressure. This paper looks deeper by comparing the results from utility-based assets to industrial-based assets. There are a few differences in these applications that might impact the partial discharge (PD) results, but most notably are operating history and the traditional usage of surge capacitors in industrial application, which are normally not used in utility applications.