Comparison of streamers characteristics in jatropha curcas methyl ester oil and mineral oil under lightning impulse voltage

Abstract

Due to their high biodegradability, non-toxicity and fire safety guarantee, vegetable-based oils are considered today as a potential substitute for mineral and synthetic liquids for electrical insulation and especially in high voltage power transformers. However, most of known vegetable oils are derived from food materials (rape-seeds, sunflower, soybeans, palms, corns and others). And one has to be vigilant to the fact that the replacement of mineral oil by natural ester fluids based on “renewably sourced” vegetable oils, does not create new problems as this could cause global food crisis due to diversion of food into insulating material oils or others (fuel). An interesting product can be jatropha curcas oil extracted from the fruits of jatropha curcas plants (“miracle tree”) which is non-food crops. These plants can be grown on marginal or degraded soils (thus avoiding the need to utilize those more fertile soils currently being used by smallholders to grow their staple crops); and it will readily grow in areas where annual rainfall levels are significantly lower than those required by other species such as rape-seeds, sunflower, palm, soybeans, corns and others. This paper presents an experimental study of streamers phenomena in jatropha curcas methyl ester oil (JMEO) and mineral oil (MO) under positive and negative lightning impulse voltages (1.2/50 μs). It is shown that basing on the shape and stopping length of streamers, JMEO could constitute a potential substitute for mineral and synthetic oils for electrical insulation and especially in high voltage power transformers.