F.A.Q

There is growing interest in using insulating vegetable oil for transformer applications. These fluids are being adopted by companies due to their excellent technical performance, environmental appeal, fire safety, and commitment to sustainability.

Biovolt vegetable oil is classified as biodegradable, meeting the strict criteria set by the EPA. Costs associated with remediating potential future spills can be reduced.

Biovolt vegetable oil is miscible with mineral oil, but high levels of contamination that compromise the key properties of the vegetable oil should be avoided. Replacing mineral oil with Biovolt vegetable oil has provided an important technical solution for transformers, offering benefits in safety, environmental performance, and higher load capacity without accelerated loss of service life.

Some additives in the new fluid may be removed during the recovery process and might need to be added back to the regenerated fluid.

The chemical structure of the insulating vegetable oil allows the fluid to have a water saturation approximately 15–20 times higher than mineral oil. This helps shift the water equilibrium toward the fluid, significantly reducing the effects of thermal degradation on the insulating paper, extending service life without reducing the fluid’s dielectric strength.

Test results, reaching voltages as high as 1800 kV in non-uniform field distribution, indicate that the breakdown voltage (BDV) and dielectric strength of Biovolt fluid are equivalent to mineral oils in all cases, except for extremely divergent geometries (needle-to-plane), where Biovolt fluid shows reduced BDV. This requires further investigation, justifying the current use of safety margins.

The classification of fire-resistant liquids depends solely on their flash point, with insulating vegetable oils falling into this category with a flash point above 300 °C. Using Biovolt allows for the elimination of fire-mitigation equipment, firewalls, and simplifies containment systems in substations.

The same analysis procedures can be used for Biovolt vegetable oil. A specific Duval triangle has been developed for insulating vegetable oils, along with an IEEE C57.155 publication for dissolved gas analysis in insulating vegetable oils.

This property is used to detect polar contaminants in mineral oils. In contrast, vegetable oils are not affected in the same way, having slightly lower values due to their chemical structure, which allows the values to remain practically stable throughout the transformer’s operational life.

Biovolt vegetable oil is not recommended for equipment that operates in continuous contact with ambient air due to its chemical structure. Even though fluid oxidation may occur over the long term, benefits such as extended transformer life could be compromised.

Used insulating vegetable oil can be recycled and also used as a raw material for biofuel production.

Thermo-vacuum treatment is an efficient method to reduce the gas and water content of an insulating vegetable oil to very low levels.