Natural ester-based insulating fluids are fire-resistant dielectric liquids derived primarily from vegetable oils. These fluids are used in transformers with increased environmental and fire safety requirements. Their composition typically includes refined vegetable oils and specially selected additives that improve their operational properties.
Natural ester-based insulating fluids provide improved fire safety due to their high flash and fire points compared with conventional mineral transformer oils. Depending on the formulation, their flash points generally exceed 300°C. These fluids are also readily biodegradable, which can help reduce their environmental impact in the event of accidental releases. However, appropriate spill prevention and containment measures remain necessary.
Another advantage of natural ester-based insulating fluids is their potential compatibility with certain other transformer insulating liquids and materials. However, their viscosity is generally higher than that of conventional mineral transformer oils, particularly at low temperatures. Therefore, compatibility, cooling performance, and operating conditions must be evaluated before replacing an existing insulating liquid.
Possible Applications
Natural ester-based insulating fluids can be used in both outdoor and indoor transformers designed or approved for their application. Their high fire points make them particularly suitable for installations where fire safety is a major consideration, including underground substations, basements, and electrical equipment located near occupied buildings.
These dielectric fluids are used in distribution transformers and certain power transformers installed at substations, industrial facilities, and electrical distribution networks. Their suitability depends on transformer design, operating conditions, and applicable technical requirements.
Natural ester-based insulating fluids can also be used in transformers located at industrial plants, public buildings, and facilities with increased environmental and fire safety requirements. Their biodegradability and fire-resistant properties can be particularly beneficial for electrical equipment installed at food processing plants, pharmaceutical facilities, and other industrial sites.
Purification and Regeneration
Natural ester-based insulating fluids can provide reliable long-term performance when operated under appropriate conditions. However, like conventional mineral transformer oils, they are subject to oxidation, contamination, and aging. Over time, these processes may affect their physical, chemical, and dielectric properties, potentially reducing transformer reliability.
Purification and regeneration processes can help maintain or restore certain properties of insulating fluids. While established treatment methods are widely used for mineral transformer oils, natural ester-based insulating fluids require special consideration due to differences in their chemical composition, viscosity, moisture behavior, and oxidation characteristics. Treatment equipment and operating parameters must therefore be selected according to the properties and condition of the fluid.
GlobeCore successfully tested its Clean Marine equipment in July 2015 while processing a natural ester-based insulating fluid. The fluid was used in a transformer installed on an offshore drilling platform approximately 250 kilometers off the Nigerian coast. Offshore installations are subject to demanding operating conditions and strict fire safety requirements, making fire-resistant insulating fluids an important option for such applications.
The tests demonstrated the capability of GlobeCore equipment to process natural ester-based dielectric fluids and improve their operating characteristics. The treatment restored the monitored fluid quality parameters to acceptable levels, allowing the insulating fluid to remain in service. Appropriate purification and maintenance can help extend fluid service life, support transformer reliability, and maintain the required level of operational safety.
