TEV Sensor-Based PD Measurements with a Focus on PRPD Patterns and FFT Analysis

Assessing the insulation condition of high-voltage equipment using non-intrusive partial discharge (PD) measurement is widespread nowadays. The transient earth voltage (TEV) method, a relatively new non-intrusive approach, operates by detecting the surface current induced by electromagnetic waves (EM) propagating from PD, which spreads out through the discontinuities of the equipment's outer surface. This paper evaluates the performance of TEV sensors compared to the IEC 60270 standard for detecting PD caused by various defect types inside and outside a metal enclosure in a laboratory setting. Phaseresolved PD (PRPD) pattern and fast Fourier transform (FFT) indicate that each defect has its own characteristic. The FFT analysis reveals that PD can only be effectively detected at specific frequencies where it is distinguishable from background noise.