A comparative study of transformer cooling performance with fire-resistant dielectric fluids

Since the banning of PCBs, fire resistant dielectric fluids are often used where an extra margin of fire safety is needed. These dielectric coolants are also referred to as `high fire point´ and `less-flammable´ fluids. The most common fire resistant fluids have inferior cooling performance compared to both PCB based fluids and conventional transformer oils. The objective of this study is to compare the cooling performance of the alternate dielectric coolants, using both a mathematical model and actual heat runs. Comparison of the heat run data and the mathematical thermal model data indicated the fire resistant fluids performed with lower thermal gradients than predicted by the mathematical model calculations