Electromagnetic Methods for PD Detection

Abstract

Partial discharge (PD) generates extremely fast PD pulse currents that radiate electromagnetic (EM) waves in the high-frequency (HF) range, the very-high-frequency (VHF) range, and the ultra-high-frequency (UHF) range with frequencies from 3MHz to 3GHz. In practice, EM PD measurement is generally divided into two categories: HF/VHF PD measurement and UHF PD measurement. Common types of PD events in the range of 3–30MHz to 30–300MHz can be adequately measured using various types of commercially available HF EM radiation sensor, such as capacitive coupler, current transformer, Rogowski coil, directional EM coupler, film electrode, and transient earth voltage sensor. As an alternative to conventional PD measurement, high-frequency EM waves generated by PD current pulses can also be measured by UHF sensors. UHF sensors can be categorized according to where they are installed (i.e. internal sensors and external sensors).