Scaled experimental study on the initial oil thickness effect on the combustion characteristic of the typical transformer insulating oil

Abstract

Compared with mineral oil, plant insulation oil has a higher flash point, excellent natural degradation ability, and higher electrical insulation. It is expected to become the main component of transformer insulation oil, but the fire safety of this oil needs to be further analyzed and improved. In this paper, a cone calorimeter was used to test the combustion of typical plant insulating oil (camellia seed oil, soybean oil) and mineral oil (25# mineral oil) under different radiant heat flows and initial oil thickness. The combustion parameters such as ignition time, heat release rate, and carbon generation rate were measured. The combustion characteristics of 25# mineral oil were greatly affected by radiative heat flow and oil thickness. The peak heat release rate and carbon generation rate of mineral oil under high heat flow (50 kW/m2) were significantly higher than those under low heat flow (25 kW/m2) and increased with the increase of initial oil thickness. Plant insulating oil (camellia seed oil and soybean oil) had similar laws, but the peak value of the heat release rate and carbon generation rate of soybean oil were relatively small. Petrella fire risk assessment method showed that the fire risk ranking in descending order was mineral oil, camellia seed oil, and soybean oil, which provided a reference for the further popularization and application of plant insulation oil transformer.