Understanding the influence of water droplet initiated discharges on damage caused to corona-aged silicone rubber
13 Sep 2017-IEEE Transactions on Dielectrics and Electrical Insulation (IEEE)-Vol. 24, Iss: 4, pp 2421-2431
TL;DR: In this paper, surface charge accumulation studies indicate that the charge retention capability of the insulating material gets reduced drastically with silicone rubber damaged due to corona, causing degradation of surface.
Abstract: Corona activity on the surface of silicone rubber has high impact on variation in hydrophobicity of the material, and on corona inception voltage (CIV) of water droplet sitting on the corona degraded surface. The CIV is high under negative DC as compared to positive DC/AC voltages. Increase in conductivity of water droplet reduces CIV. Surface charge accumulation studies indicate that the charge retention capability of the insulating material gets reduced drastically with silicone rubber damaged due to corona causing degradation of surface. Irrespective of the number of cycles of corona discharge activities carried out, the time constant of charge decay, after the removal of charge injection, remains the same. The water droplet initiated discharges under AC and DC voltages radiate UHF signal in the bandwidth 0.3–1.2 GHz. With single droplet sitting on top of the corona damaged silicone rubber, the amount of charge retained by the water droplet is low when the droplet is placed and charged immediately after corona discharge activity to surface of the insulating material. When the water droplet is placed after a certain time period, the charge accumulation characteristics of silicone rubber are regained. Leakage current measured during water droplet discharge studies through recurrent plot (RP) analysis reveals that, under AC voltage, it is possible to classify corona inception, arcing and bridging of water droplet between high voltage and ground electrode. The RP obtained for the current signals generated due to water droplet discharges under positive and negative DC voltages are different. The amount of damage caused to silicone rubber due to water droplet is high under negative DC voltage as compared to positive/AC voltages. While correlating the level of damage to the insulating material due to water droplet and the RQA parameters of RP, it is observed that higher the recurrence rate along with high determinism can cause severe damage to the insulating material. Structural analysis using ATR-FTIR and pyrolysis-GC/MS studies reveal significant functional group variation on surface of silicone rubber, especially when the number of cycles of corona ageing is more.
Citations
More filters
TL;DR: In this paper, the AC charged aging test of the silicone rubber sample in an acid environment was carried out, and then its physicochemical and electrical properties were tested, including microscopic morphology, hydrophobicity, infrared spectroscopy, and electrical strength.
3 citations
TL;DR: In this article , the AC charged aging test of the silicone rubber sample in an acid environment was carried out, and then its physicochemical and electrical properties were tested, including microscopic morphology, hydrophobicity, infrared spectroscopy, and electrical strength.
3 citations
01 Mar 2019
TL;DR: In this article, the performance of electrically stressed silicone rubber insulating material in a cyclic salt fog test has been investigated, and surface potential accumulation studies indicate that salt fog aged silicone rubber shows characteristic variation in accumulated potential magnitude and the decay characteristics.
Abstract: The present work investigates the performance of electrically stressed silicone rubber insulating material in a cyclic salt fog test. Corona Inception Voltage due to water droplet initiated discharges changes after salt fog ageing. The Ultra High Frequency signals radiated during corona discharge activity under AC voltages have a frequency span of 0.8–1.5 GHz, whereas under DC voltages span lies in the range of 0.5–1.5 GHz. Contact angle reduces with the increase in number of salt fog ageing cycles. Surface potential accumulation studies indicate that salt fog aged silicone rubber shows characteristic variation in accumulated potential magnitude and the decay characteristics. Further tdv/dt of surface potential decay characteristics enables to understand the charge penetration depth. Weight loss studies and surface roughness analysis during salt fog test are used to quantify the amount of damage.
2 citations
07 Apr 2019
TL;DR: In this article, the effects of contaminated water droplets on the surface corona discharge characteristics of composite insulators in arid areas were studied, and the effect of conductivity of different contamination types on the corona onset voltage was studied.
Abstract: Corona discharge is a common gas discharge phenomenon on the surface of power equipment such as high-voltage transmission lines and insulators. Long-term corona discharge will gradually damage the insulation properties of power equipment, threatening the safe and stable operation of the power system. With the continuous development of China's high-voltage transmission lines, the entire transmission network is spread all over the country. The climate varies greatly in different regions, and the insulators will be in an environment of drought, humidity, ice coating and heavy pollution. The degree of corona discharge will be affected by electric field strength, humidity, contamination and other factors. In extreme operating environments, local corona discharge activity on the insulator surface may increase. The energy generated by the corona discharge and the effect of the electric field force will damage the surface characteristics of the insulating material. Long-term repeated action will accelerate the aging of composite insulators and shorten the service life. Therefore, it is of great theoretical significance and application value to study the corona discharge characteristics of composite insulator surfaces in extreme environments. At present, research on the surface corona discharge of insulators mainly focuses on non-contact detection of abnormal discharge activities caused by factors such as contamination and rainfall. However, there are few studies on the effects of extreme environments on the corona discharge characteristics of insulator surfaces. In this paper, the effects of contaminated water droplets on the surface corona discharge characteristics of composite insulators in arid areas were studied. In arid areas, especially in summer, the air is dry and the temperature difference between day and night is large. After reaching the dew point temperature, the surface of the insulator will easily form morning dew. Surface contamination dissolved in the morning dew will form contaminated water droplets, which will affect corona discharge activity. Long-term corona discharge not only accelerates the aging of the insulating surface material, but also increases the risk of insulator flashover. To this end, this paper built a corona discharge test platform to detect the corona discharge activity on the surface of the insulator. The effects of contaminated water droplets on the corona discharge activity of the composite insulator surface and the corona onset voltage were studied. Firstly, NaCl, CaSO 4 and Na 2 SO 4 were used to simulate the salt contamination in arid areas. The pollution severity was simulated by changing the conductivity. The effect of conductivity of different contamination types on the corona onset voltage was studied. Secondly, by changing the number of contaminated water droplets, the mixing ratio of the three salts, and adding kaolin, the water droplets in the actual operating environment were simulated, and the variation of the corona onset voltage was studied. In addition, the force and deformation of the contaminated water droplets under the influence of the electric field were analyzed. The results show that different types of contamination reduce the corona onset discharge voltage to different extents. The higher the conductivity, the lower the corona onset voltage. By analyzing the characteristic curve between the number of water droplets and the corona onset voltage of the mixed contamination water droplets, it is found that the type and content of the contamination and the number of water droplets will greatly affect the corona discharge activity. The research results of this paper have a certain reference for the design of composite insulators in arid areas.
2 citations
Cites methods from "Understanding the influence of wate..."
...[5] used a needle-needle electrode to study the effect of corona discharge induced by water droplets on DC and AC voltages on the aging of silicone rubber materials....
[...]
...This conclusion is consistent with [5]....
[...]
1 citations
References
More filters
TL;DR: In this paper, a combination of traditional kinetic formal treatments and computer simulation has been made to analyze polydimethylsiloxane (PDMS) thermal degradation, and it was shown that PDMS thermally decomposes to cyclic oligomers through Si-O bond scission in a chain-folded cyclic conformation energetically favored by overlapping of empty silicon d-orbitals with orbitals of oxygen and carbon atoms.
635 citations
TL;DR: In this paper, the products of the thermal degradation of polydimethylsiloxane (PDMS) are determined by the heating conditions, since two competing mechanisms are involved: molecular splitting of oligomers from loop conformations of the PDMS chain and assistance on the part of empty silicon d-orbitals.
430 citations
TL;DR: In this paper, contact angle measurements of a high-temperature-vulcanized polydimethylsiloxane (PDMS) elastomer have been obtained for different periods of time in dry air.
406 citations
TL;DR: In this article, the evolution of volatile materials from pure poly(dimethylsiloxane) heated under temperature programmed conditions (10° min−1 under vacuum) is detectable at 343° and reaches a maximum at 443°.
347 citations
TL;DR: In this article, a critical evaluation of the chemical and physical mechanisms responsible for hydrophobicity loss and recovery is presented, where the authors evaluate the properties of silicone rubbers based on polydimethylsiloxane (PDMS).
Abstract: Water repellency, high surface resistivity, vandalism resistance, low density and good processability have made silicone rubbers based on polydimethylsiloxane (PDMS) very attractive materials in housings for outdoor insulation. Their ability to recover hydrophobicity after oxida. tion or contamination is of paramount importance and this is the topic of this review. A critical evaluation of the chemical and physical mechanisms responsible for hydrophobicity loss and recovery is presented.
318 citations