Abstract: A dry-type transformer having an iron core, with high voltage and low voltage coils encapsulated in casting resin. The high and low voltage windings may be cast separately, or together. Either or both of the coils may have integral axial cooling channels, as may the annular axial space between the inner and outer windings (usually low voltage and high voltage, respectively). Coil cross-section is a modified oval (Rectoval.TM.) shape, in that the sides of the coil are substantially linear and the ends of the coils are substantially semi-circular. The aspect ratio (L/W) of the coil, when viewed in radial cross-section, ranges from greater than 1.0 to about 2.5. The rectangular nature of the coil allows for the use of a core member having a rectangular cross-section, thereby reducing the manufacturing expense involved with shaping the core member. The circular nature of the ends of the coil provide improved strength similar to that of circular/cylindrical coils.