Turret-Electrode Antenna for UHF PD Measurement in Power Transformers - Part I: Introduction and Design

This contribution is the first part of a two-part series which deals with proposing a new type of UHF probe to overcome problems of UHF partial discharge (PD) measurement in power transformers. In the first part, the main obstacles of using the UHF technique in power transformers including problems of installation, unfeasibility of calibration, low sensitivity, etc. are addressed. Moreover, a new type of UHF sensor called the “Turret-Electrode” antenna is presented to deal with the above obstacles. In the new antenna, the transformer turrets employed as the housing of open waveguide antenna (horn antenna with zero flare angle), while an electrode inside of the turret is designed to capture the electromagnetic (EM) waves produced by the PD signals inside of the transformer tank. The significant characteristics of the proposed antenna are investigated in detail and a prototype of the antenna is investigated via practical measurements. The results show the antenna parameters are quite appropriate for online PD measurement. The second part of the paper shows how the proposed antenna can resolve the problems pertaining to the UHF PD measurement in power transformers.