Investigation of the Influence of Temperature and Relative Humidity on Partial Discharge in Twisted Pairs and Electric Motors

This research investigates the combined influence of temperature and relative humidity on Partial Discharge (PD) activity, a key indicator of insulation health in rotating machinery. While PD detection is a well-established field, its application to low-voltage machines is challenging, since environmental factors affect PD in real-world scenarios. This study compares PD measurements on twisted-pair wire samples against a complete electrical machine pulled from an industrial installation. The findings reveal a significant deviation between the two. The complex insulation system of a full machine, comprising impregnating resins and flexible laminates, fundamentally alters the impact of temperature and humidity on PD behavior compared to simplified laboratory models of the individual components. These results demonstrate that extrapolating data from small-scale samples to complex machinery can be challenging, due to counter intuitive interactions. The entire insulation system’s design and its interaction with operating conditions and ageing influence must be considered for accurate diagnostics, highlighting a critical area for improving the reliability and safety of modern electrical machines.