Cargill Envirotemp FR3 fluid

Envirotemp FR3 is a Cargill natural ester dielectric fluid for liquid-filled transformers. It is plant-based and made mostly from vegetable oil, specifically soybeans. It has a fire point of 360 °C. It is FM Approved and UL Classified as a less-flammable liquid under NEC Article 450-23. Cooper Envirotran Solar transformers and Cooper three-phase pad-mounted compartmental transformers are available filled with FR3 fluid. FR3 mixes fully with mineral oil, so distribution and power transformers can be retrofilled with it. Cargill recommends that residual mineral oil stay at or below 7 percent, and it recommends a design review for transformers above the 138 kV class. Cargill recommends FR3 for transformers that do not breathe freely. Free-breathing units need a system that limits air exchange with the fluid. After a retrofill, the transformer may run about 5 °C warmer, and the voltage class does not need to be derated. Cargill says loading capacity may rise by up to 15 percent if the transformer is rerated. The fluid draws moisture out of paper insulation. It is biodegradable and non-toxic, which lowers cleanup costs after a spill. Some fuse assemblies have lower current ratings when mounted in the sidewall in FR3 fluid than in mineral oil. Check the fuse catalog ratings for the fluid you are using.