Modeling and Analysis of Surface Contamination in Ceramic and Polymeric Insulators Using Partial Discharge Signal Characteristics

Abstract

This study aimed to model and analyze the impact of surface contamination on ceramic and polymeric insulators by characterizing and comparing their partial discharge (PD) signal behavior to support condition-based monitoring and predictive design. An experimental laboratory design was employed to expose medium-voltage ceramic and polymeric insulators to controlled contamination layers prepared with standardized saline and artificial pollutants. PD signals were captured under alternating current stress using an IEC 60270–compliant setup consisting of a high-voltage source, coupling capacitor, and Rogowski coil/high-frequency current transformer sensors. Raw signals underwent wavelet-based denoising to suppress environmental noise and were further analyzed using Fast Fourier Transform (FFT) for spectral features and phase-resolved partial discharge (PRPD) mapping to visualize discharge activity across the AC cycle. Equivalent electrical models of contaminated surfaces were developed to simulate PD inception and growth, and the outputs were validated against laboratory measurements. Ceramic insulators exhibited an abrupt transition from sporadic to high-energy discharges once contamination created a conductive film, reflected by sharp increases in apparent charge and dense PRPD clusters around voltage peaks. Polymeric insulators demonstrated a more gradual rise in PD activity with smaller but persistent pulses distributed across the cycle. FFT analysis revealed dominant low-to-mid frequency peaks intensifying faster in ceramics, while polymeric responses remained broader and less concentrated. The electrical models closely matched experimental PD thresholds and spectral signatures, confirming their ability to predict contamination-driven surface breakdown. Surface contamination strongly influences PD activity, and material type governs the discharge evolution pathway.