ABSTRACT
This paper presents the physical, chemical, dielectric properties, and the extraction process of natural ester oil, mineral oil and synthetic ester oil. Renewable resources are derived from plant, animal fats, crops, fruits and their seeds, such as soybean oil, olive oil, mustard oil, sunflower oil, palm oil, coconut oil, cottonseed oil and canola oil etc. The seed oil was refined by considering the oil with alkali to remove the free fatty acids. Polychlorinated biphenyls were banned due to their health and environmental hazards. Persistent biodegradability and toxicity have been detected in rainwater, in human tissue, many species of birds and fish, the problem of environmental pollution had still not been solved due to being a petroleum product. Natural resources have good dielectric properties and are considered best alternate of mineral oil for usage in oil-filled type transformers as an insulation and coolant. Natural ester oil is deliberated to be one of the feasible alternatives for mineral oil and silicone fluid due to eco-friendly in nature, due to non-toxic material which will not produce any dioxin and toxic hazards in environment, low explosion risk, high flash, less flammable, less time take for biodegradable and high value of pour point indicates better insulation oil medium for transformer.
