No abstract

UHF method to detect partial discharge phenomenon has been proven to be an effective way. Many types of UHF antennas have been developed in order to achieve a better sensitivity and accuracy in certain bandwidth (300 MHz -3.0 GHz) for detecting the ultra-high frequencies generated by partial discharge. Bowtie antenna is one type of broadband antenna proven to be sensitive, accurate and easily designed and fabricated. This paper focused on the bowtie antenna characteristics both the measurement using vector network analyzer and simulation. The finite-difference time-domain (FDTD) technique is applied to model and confirm the antenna under observation in this research and later on modify to enhance the better performance. Simulation has proven, antenna achieves the optimum angle at flare angle of 60° as per simulation within the frequency range over 913 MHz -3.0 GHz as per measurement. The simulation results are used to construct the new modified antenna which showed the better sensitivity in the frequency bandwidth of partial discharge. The Gigahertz transverse electromagnetic (GTEM) like environment also used to simulated the sensitivity of antenna as compared to the calibration value approximately 11.0 mm.

Partial discharge (PD) properties and dissolved gas analysis (DGA) are investigated on two kinds of fatty acid alkyl esters synthesized from palm oil with additive, namely Pastell 2H-08 and Palm Fatty Acid Ester (PFAE) to be adopted in power transformers. For comparison, the properties of mineral oil which is commercially used transformer oil were also investigated in the research works. The results revealed that PD repetition rate number of the ester oils with additive increase remarkably at above 15 kV rms of voltage application than that of mineral oil. PD charge of ester oils with additive tends to saturate at about 10,000 pC, while PD charge of mineral oil seems to keep increasing with increasing the applied voltage at above 20 kV rms . The amounts of generated hydrocarbon gases in ester oils with the additive are higher than that of mineral oil. It is found that combustible gas pattern of the ester oils with the additive are different from that of conventional mineral oil. Duval analysis of ester oils with additive and mineral oil are classified as high energy electrical discharge, while for mineral oil is classified as low energy electrical discharge.