Diagnostics of medium-voltage motors

Contribution deals with the problem of insulating system´s condition diagnosing with aim to upgrade the level of its real state ranking. After the description of diagnosing methodology used real on-site acquired data are presented. Main accent is at monitoring of discharge activities. This method is perhaps the only, which enables to detect smaller anomalies in high-voltage insulation systems as well. It´s most important requirement is the reliable pattern-of-defect recognition upon measured apparent charge´s phase-distribution. This objective can be solved by discharge-activity simulation. Data comparison from real measurements and from created digital discharge-activity simulator with the possibility of statistical data analysis validates the correctness of selected technique.