A thermal model for optimized distribution and small power transformer design

A thermal model for the design of rectangular layer windings for transformers is summarized. The model calculates thermal gradients across layers, to and from the core, and from the no-duct region under the core iron to the ducted region. The model evaluates the effects of cooling duct quantity, location, and size on the thermal performance. The model includes temperature dependent fluid properties and electrical resistivity. Fluids include mineral oil, high temperature hydrocarbons, and silicone. The overall computer program also includes the tank and radiator cooling with provisions to evaluate solar heating and wind effects. The model allows the transformer designer to control the hottest spot temperature rise and optimize the thermal performance of the transformer to meet IEEE standards and user overload requirements.