This study attempts to elucidate whether the addition of micro and/or nano-silica(SiO_(2))particles can enhance the resistance of pure polydimethylsiloxane against synergistic effects of UV,temperature and high-voltag...This study attempts to elucidate whether the addition of micro and/or nano-silica(SiO_(2))particles can enhance the resistance of pure polydimethylsiloxane against synergistic effects of UV,temperature and high-voltage stress.Four types of composites(U-SR,M-SR,MN-SR and N-SR)are fabricated by adding micro and/or nano-silica particles and then subjected to multi-stress degradation in a test chamber.Results show that there is an apparent surface discoloration in the form of yellowish pale tint and a significant resistance to hydrophobicity reduction is offered by N-SR and MN-SR followed by M-SR and U-SR.Scanning electron microscopy and surface roughness findings proclaimed that N-SR and MN-SR offer excellent resistance against filler exposure and an increase in surface roughness.There is a minor reduction in absorbance level of Si(CH_(3))_(2) and Si-O-Si functional groups of composites but interestingly,hydrophilic hydroxyl group absorbance level is found higher in the U-SR comparatively.Furthermore,dielectric response measurements indicate considerable sensitivity to weathering with N-SR and MN-SR giving the lowest dielectric loss.Results indicate that the addition of nano-silica to pure and micro-silica filled SR can enhance its UV weathering resistance considerably by building an effective UV shielding layer.展开更多
Thermal depolymerisation induced tracking and erosion of polymeric insulators is one of the key insulation failure modes and this process adversely affects the reliability of power delivery networks.This study reports...Thermal depolymerisation induced tracking and erosion of polymeric insulators is one of the key insulation failure modes and this process adversely affects the reliability of power delivery networks.This study reports the tracking,erosion and thermal distribution of micron-AlN and micron-AlN+nano-SiO_(2)co-filled silicone rubber composites.A tracking-erosion model is presented to explain how the co-filled set of particles directly affects such mechanisms.Aluminium nitride(AlN:5-10μm)and silica(SiO_(2):20 nm)particles were procured for fabricating test samples.The inclined plane test according to IEC 60587 was carried out using tracking voltage method 2 with an initial applied voltage of 3 kV and a ramping rate of 0.25 kV/h over the duration of 240 min.Measurement results show co-filled composites exhibit significantly lower physical tracking and erosion as compared to micron-AlN filled composites.Thermal accumulation and average leakage current in co-filled composites are found noticeably lower than micron-filled counterparts.Moreover,the increased surface area of the combined co-filled particles in the composites provides better scattering and reduce secondary electron collision.This may impede the release of high energy causing thermal degradation.展开更多
Measurement of partial discharge(PD)is a vital method to assess the health of the electrical insulation in high-voltage power equipment.As diagnostic testing at very low frequency(VLF)is increasingly being used,it is ...Measurement of partial discharge(PD)is a vital method to assess the health of the electrical insulation in high-voltage power equipment.As diagnostic testing at very low frequency(VLF)is increasingly being used,it is important to investigate PD behaviours under such a low-frequency voltage excitation.This study presents the PD characteristics at VLF excitation under different applied voltage waveforms,including sinusoidal and trapezoid-based waves.Also,the effects of cavity size on PD behaviours at VLF are investigated.Experiments were performed to measure PDs in a cylindrical void bounded by solid insulation.The results show that discharge activities at VLF,in general,exhibit lower magnitude and repetition rate when compared with power frequency.Also revealed is the strong dependency of discharge parameters on the rate of voltage rise.Physical mechanisms to explain discharge behaviours are given.展开更多
文摘This study attempts to elucidate whether the addition of micro and/or nano-silica(SiO_(2))particles can enhance the resistance of pure polydimethylsiloxane against synergistic effects of UV,temperature and high-voltage stress.Four types of composites(U-SR,M-SR,MN-SR and N-SR)are fabricated by adding micro and/or nano-silica particles and then subjected to multi-stress degradation in a test chamber.Results show that there is an apparent surface discoloration in the form of yellowish pale tint and a significant resistance to hydrophobicity reduction is offered by N-SR and MN-SR followed by M-SR and U-SR.Scanning electron microscopy and surface roughness findings proclaimed that N-SR and MN-SR offer excellent resistance against filler exposure and an increase in surface roughness.There is a minor reduction in absorbance level of Si(CH_(3))_(2) and Si-O-Si functional groups of composites but interestingly,hydrophilic hydroxyl group absorbance level is found higher in the U-SR comparatively.Furthermore,dielectric response measurements indicate considerable sensitivity to weathering with N-SR and MN-SR giving the lowest dielectric loss.Results indicate that the addition of nano-silica to pure and micro-silica filled SR can enhance its UV weathering resistance considerably by building an effective UV shielding layer.
基金This work was financially supported by a Postdoctoral Writing Fellowship of Faculty of Engineering,University of New South Wales,Australiathe State Key Laboratory of Electrical Insulation and Power Equipment(SKLEIPE)Opening Project of Xi'an Jiaotong University,P.R.China.
文摘Thermal depolymerisation induced tracking and erosion of polymeric insulators is one of the key insulation failure modes and this process adversely affects the reliability of power delivery networks.This study reports the tracking,erosion and thermal distribution of micron-AlN and micron-AlN+nano-SiO_(2)co-filled silicone rubber composites.A tracking-erosion model is presented to explain how the co-filled set of particles directly affects such mechanisms.Aluminium nitride(AlN:5-10μm)and silica(SiO_(2):20 nm)particles were procured for fabricating test samples.The inclined plane test according to IEC 60587 was carried out using tracking voltage method 2 with an initial applied voltage of 3 kV and a ramping rate of 0.25 kV/h over the duration of 240 min.Measurement results show co-filled composites exhibit significantly lower physical tracking and erosion as compared to micron-AlN filled composites.Thermal accumulation and average leakage current in co-filled composites are found noticeably lower than micron-filled counterparts.Moreover,the increased surface area of the combined co-filled particles in the composites provides better scattering and reduce secondary electron collision.This may impede the release of high energy causing thermal degradation.
文摘Measurement of partial discharge(PD)is a vital method to assess the health of the electrical insulation in high-voltage power equipment.As diagnostic testing at very low frequency(VLF)is increasingly being used,it is important to investigate PD behaviours under such a low-frequency voltage excitation.This study presents the PD characteristics at VLF excitation under different applied voltage waveforms,including sinusoidal and trapezoid-based waves.Also,the effects of cavity size on PD behaviours at VLF are investigated.Experiments were performed to measure PDs in a cylindrical void bounded by solid insulation.The results show that discharge activities at VLF,in general,exhibit lower magnitude and repetition rate when compared with power frequency.Also revealed is the strong dependency of discharge parameters on the rate of voltage rise.Physical mechanisms to explain discharge behaviours are given.
