Emission and Propagation Mechanisms of PD Pulsesfor UHF and Traditional Electrical Measurements
International Journal on Electrical Engineering and Informatics
Partial Discharge measurements are considered as a powerful technique for testing and monitoring the condition of high-voltage insulations sinceit serves as an early breakdown indicator. In the present contribution, the authors describe the fundamentally different propagation mechanisms of electrical impulses in the conventional measurement frequency range according IEC 60270 and in the ultra-high frequency range. Electromagnetic field simulation and measurements in GIS are used to elaborate
... sed to elaborate the signal propagation mechanisms. The low-frequency components of the PD signals propagate mainly via the conductor, whereas the high-frequency components (UHF signals) are radiated as electromagnetic waves. The sensitivity and spectrum of the measurement depends strongly on the geometric position of the PD, damping and resonances of the propagation path, and the frequency response of the receiver. Due to their different, complex propagation mechanisms, apparent charge level after IEC 60270 and UHF antenna peak voltage cannot be compared directly nor can frequency spectra be easily used for deriving information about the physical nature of the defect.