Simulation of the diffusion behavior of water molecules in palm oil and mineral oil at different temperatures

AC breakdown channel of PPLP multi-layer insulation for HTS cable

Mineral oil has traditionally been used as a cooling fluid in power transformers, but its low biodegradability and low fire point have motivated the search of alternatives. In this work, six different dielectric fluids have been studied, including four vegetable liquids, from sunflower, rapeseed, soybean, and palm, one synthetic ester and a mineral oil used for comparison. These oils were subjected to an accelerated thermal ageing in glass vessels at 150°C for four weeks (672 hours) in presence of Kraft insulating paper. Different oils parameters were measured during the ageing, i.e. breakdown voltage, dielectric dissipation factor, permittivity, DC resistivity, density, kinematic viscosity, flash and fire points, interfacial tension, acidity, and dissolved gases; additionally, the degree of polymerisation (DP) of the paper was measured. Results showed that the changes of the natural esters properties, except for the palm oil, were similar along the ageing time. Palm oil results were similar to those of the mineral oil, whereas synthetic ester showed a behaviour similar to natural esters. The kraft paper degradation was higher in the mineral oil, followed by the synthetic ester and the palm oil. No significant differences were found in the ageing with the natural esters.

https://doi.org/10.1109/access.2023.3239895

Understanding the Ageing Performance of Alternative Dielectric Fluids

Mineral oil has traditionally been used as a cooling fluid in power transformers, but its low biodegradability and low fire point have motivated the search of alternatives. In this work, six different dielectric fluids have been studied, including four vegetable liquids, from sunflower, rapeseed, soybean, and palm, one synthetic ester and a mineral oil used for comparison. These oils were subjected to an accelerated thermal ageing in glass vessels at 150°C for four weeks (672 hours) in presence of Kraft insulating paper. Different oils parameters were measured during the ageing, i.e. breakdown voltage, dielectric dissipation factor, permittivity, DC resistivity, density, kinematic viscosity, flash and fire points, interfacial tension, acidity, and dissolved gases; additionally, the degree of polymerisation (DP) of the paper was measured. Results showed that the changes of the natural esters properties, except for the palm oil, were similar along the ageing time. Palm oil results were similar to those of the mineral oil, whereas synthetic ester showed a behaviour similar to natural esters. The kraft paper degradation was higher in the mineral oil, followed by the synthetic ester and the palm oil. No significant differences were found in the ageing with the natural esters. 

/pdf/understanding-the-ageing-performance-of-alternative-2woyyvm7.pdf

Investigation on the partial discharge characteristics of eco-friendly nanofluid insulation of corn oil nanofluid

The AC breakdown properties of Kraft paper, pressboard and the enamel insulation layer in rice oil, peanut oil and corn oil were investigated under both new and aged conditions. The ageing of paper insulators and the enamel insulation layer in oils with the open cup method was carried out at 130 oC for 500 h in an air circulation oven. The puncture breakdown strength was determined by varying the number of layers and thickness of Kraft paper, while various electrode gap distances were used to measure the surface breakdown strength. Experimental results show that the breakdown strength and the tensile strength of paper insulators impregnated with these vegetable oils are comparable to that in mineral oil, and the surface breakdown strength of paper insulators is slightly affected by types of impregnating oils. The ageing significantly reduces both the breakdown strength and the tensile strength of paper insulators in investigated oils. In addition, it was also found that the enamel layer in vegetable oils withstood higher puncture breakdown strength than in mineral oil, and the ageing process significantly reduced the puncture breakdown strength of the enamel layer. This enamel layer was observed to markedly enhance the surface breakdown strength of pressboard.

https://ietresearch.onlinelibrary.wiley.com/doi/epdf/10.1049/iet-smt.2018.5580

Long Phuoc Nguyen

Papers

Investigation of AC breakdown properties of paper insulators and enamel insulation impregnated with rice oil, corn oil and peanut oil for transformers