Comparative Analysis of Lightning Properties of Different Types Ester Fluids

- A&A Fratelli Parodi. A vegetable based synthetic ester Paryol Tras 24 (marked as SE), a high oleic sunflower natural ester Paryol Electra 7426 (NE), and a vegetable based blended ester Paryol Agrilec 6312 (BE) were tested. These were compliant with the IEC 61099:2010, 62770:2024, and 63012:2019 respectively. Dielectric liquids listed have been recently introduced, therefore obtained results were compared with other ester liquids previously tested by the High Voltage Group of Lodz University of Technology. All tests were performed in a point to sphere electrode system, with an inter-electrode gap of 25 mm, for both negative and positive polarity, and standard lightning impulse voltage (1.2/50 µs). The Vi value was identified based on the light pulses recorded by the photomultiplier during the development of discharge. LIBV was determined by the step method in line with IEC 60897:1987 standard.

The voltage waveforms were recorded using an oscilloscope. Additional metric used to categorise dielectric liquids was acceleration voltage (Va). It is the voltage at which the discharges’ order of propagation shifts from slow to fast. Va was determined by applying higher voltage values compared to previously determined LIBV and observing the time to breakdown on recorded voltage oscillograms. The research was supported by photos of discharges recorded with a high-speed camera.

The findings show that the lightning performance of the evaluated synthetic, natural, and blended esters are comparable to that of their analogues avaliable on the market. There are minor variations in the obtained results that could lead to conclude either in favour of or against using a given liquid.