UHF-Based Partial Discharge Diagnostics in SF6-Alternative Gases

This paper specifically focuses on ultra-high frequency-based PD measurement analysis for three candidate alternative gases. A series of custom-designed test cells were fabricated to replicate idealized defect topologies commonly found in GIS. Partial discharge inception voltage measurements were performed using all test gases for different pressures to compare their performance. The characteristic features of phase-resolved partial discharge data are compared for the different defects in both C4-FN gas mixtures and atmospheric gases. By referencing historically established PD characteristics in SF6, we evaluate the applicability of existing diagnostic criteria to the new gas mixtures and identify case-specific deviations. Fast

Fourier Transform (FFT) spectral analysis reveals defect-dependent characteristics, with distinct frequency peaks observed across different defect types. These observations are further supported by variations in the energy distribution specific to each PD defect.

These findings link key PD metrics with eco-friendly gases to identify defect signatures.

Frequency response analysis enables the distinction of different PD defects, as each type of defect produces a distinctive FFT spectrum and energy distribution. The findings are particularly relevant to industry, especially for network operators requiring condition monitoring of assets insulated with alternative gases using UHF PD sensors.