Partial discharge pulse propagation in power cable and partial discharge monitoring system

Partial discharge (PD) based condition monitoring has been widely applied to power cables. However, difficulties in interpretation of measurement results (location and criticality) remain to be tackled. This paper aims to develop further knowledge in PD signal propagation in power cables and attenuation by the PD monitoring system devices to address the localization and criticality issues. As on-line or in-service PD monitoring sensors commonly comprise of a high frequency current transformer (HFCT) and a high-pass filter, the characteristics of detected PD pulses depend on the attenuation of the cable, the HFCT used and the filter applied. Simulation of pulse propagation in a cable and PD monitoring system are performed, based on analyses in the frequency domain using the concept of transfer functions. Results have been verified by laboratory experiments and using on-site PD measurements. The knowledge gained from the research on the change in pulse characteristics propagating in a cable and through a PD detection system can be very useful to PD denoising and for development of a PD localization technique

Determination of essential oil from Scutellaria baicalensis Georgi (Lamiaceae) by GC-MS, and assessment of its insecticidal properties

Purpose: To isolate essential oil from the aerial parts of Scutellaria baicalensis using GS-MS, and to assess its insect-killing effect against booklice (Liposcelis bostrychophila).Methods: The oil from the aerial parts of S. baicalensis was hydro-distilled and subjected to gas chromatographic and mass spectroscopic (GC-MS) techniques. The components of the oil with insectkilling potentials were fractionated through bioactivity-guided isolation, and the isolated oil and its components were screened for their toxic effects on booklice.Results: A total of 31 components were obtained, with eugenol as the most abundant. When used to fumigate S. baicalensis, the oil and two of its constituents (myristicin and eugenol) exerted appreciable toxic effects. Moreover, the oil and its isolates manifested contact toxicity against booklice.Conclusion: These findings indicate the insecticidal benefits of the essential oil and its components against Liposcelis bostrychophila