Monopole Coil Antenna for Partial Discharge Detection in High-Voltage Equipment

Abstract

This study proposes a novel monopole coil antenna for detecting partial discharge (PD) in high-voltage (HV) and medium-voltage (MV) equipment. The proposed antenna addresses the critical challenge of distinguishing PD-generated signals from external electromagnetic interference (EMI). The integration of a low-impedance coil at power frequencies enables the antenna to achieve three key advantages. This technology is expected to enable safe installation without antenna charging, even in strong electromagnetic fields, based on the coil's near-zero DC impedance at power frequencies. Furthermore, it facilitates frequency-selective reception in the 30-300 MHz band, thereby suppressing power-line harmonics below 30 MHz and high-frequency ambient noise above 300 MHz. Finally, it enables detection of partial discharges at least 200 pC under the experimental conditions, representing a substantial improvement over conventional antenna-based approaches. Experimental validation demonstrated a sensitivity enhancement of 13-21× over a bilog antenna at equivalent phase-center placement, arising from nearfield proximity and frequency-selective termination. The simple wire design (1 mm diameter) enables easy retrofitting in existing equipment without structural modifications.