Partial discharge behaviour of cross-linked polyethylene - natural rubber blends nanocomposites as electrical insulating material

• Main Author: Wan Mohd. Zawawi, Wan Akmal ‘Izzati
• Format: Thesis
• Language: English
• Published: 2015
• Subjects: TK Electrical engineering. Electronics Nuclear engineering
• Online Access: http://eprints.utm.my/id/eprint/54596/1/WanAkmal%E2%80%98IzzatiWanMohdZawawiMFKE2015.pdf; http://eprints.utm.my/id/eprint/54596/; http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:86668
• Institution: Universiti Teknologi Malaysia

Polymeric materials are widely used in power apparatus as electrical insulation, especially for high voltage cable insulation. However, partial discharge (PD) has always been a predecessor to major faults and problems in this field. By adding a weight percentage (wt%) of a nanofiller to the electrical insulation, the physical and electrical properties can be enhanced. In this research, natural rubber (NR) blends polymeric material of cross-linked polyethylene (XLPE) as insulation was combined with nanofillers, namely nanosilica (SiO2) or organo-montmorillonite (O-MMT). Seven samples comprising six compositions of a blend of 20 wt% NR and 80 wt% of XLPE with 2, 4, and 8 pph from SiO2 and O-MMT, and one without nanofiller were used in the experiments. Two PD tests were carried out based on CIGRE Method II technique, where 7 kVrms high voltage was applied for 1 hour and 3 hours. LabVIEW™ program was used to analyse the PD data captured from the on-line and off-line PD measuring system where PD pulse magnitudes and number of PD occurrences were measured. Results showed that samples of NR-XLPE blended with SiO2 have lower PD number than the O-MMT samples. Scanning Electron Microscopy images showed that smoother surfaces were observed as the wt% of the nanofiller increased, indicating that the samples were less degraded. Energy Dispersive X-ray measurement of samples containing SiO2 emitted more stable amounts of oxygen and carbon contents when exposed to high voltage. Analysis on Fourier Transform Infrared spectroscopy showed a reduction of OH groups in the samples. Using QuickField™, the electric field distribution of the samples confirmed that in series of 2, 4, and 8 pph nanofiller loading, there is a correlation between the amount of nanofiller and discharge activities. The findings have shown that SiO2 and O-MMT and the different loadings do enhance the insulation properties when mixed with NR-XLPE.