Evaluation of several techniques and additives to de-moisturise vegetable oils and bench mark the moisture content level of vegetable oil-based dielectric fluids

Highly biodegradable and renewable seed-based oils can be an alternative source of dielectric fluids to replace the non-friendly mineral oil-based dielectric fluids. However, the high moisture content of vegetable oils is not suitable for a viable dielectric fluid formulation for safe, economic and trouble free operation of power and distribution transformers. The reduction of the moisture level of vegetable oils to an acceptable and safe working level is one of the major steps of development of a highly biodegradable and environment friendly dielectric fluid. This paper describes an analytical method to bench mark the moisture content level of vegetable oil-based dielectric fluids and evaluates several techniques and products for lowering the moisture content level of vegetable oils below the bench marked level for safe operation of power and distribution transformers. The paper also presents the acute toxicity and biodegradation characteristics of the processed vegetable oil-based base fluid to demonstrate its environmental compliance. Experimental results of de-moisturisation using some absorbing materials indicate that the moisture level of vegetable oils can be reduced below the bench marked level to ensure the functional behaviour of vegetable oil-based dielectric fluids. The acute toxicity and biodegradation tests of the base fluid indicate virtually non-toxic and readily biodegradable characteristics for dielectric fluid that can be formulated using the base fluid.