Abstract: A cooling system (11) is provided for electrical components (10, 90) in which passageways (21) are inserted in non-magnetic cores of the electrical components, and in which the passageways (21) provide both inflow and outflow of a cooling medium. The passageways (21) can be formed by drilling holes in a core of an electrical component or by mounting closed-end tubes (16–19) on a base plate-cooling manifold (20) or can be part of a conduit assembly (70). The tubes (16–19, 71) are split-flow closed-end tubes inserted from one end of the electrical component (10, 90). The tubes and passageways (16–19, 21, 71) may be partitioned into two halves or into two concentric portions. O-ring seals (28) are provided around the base of the tubes to seal the areas where the passageways communicate with hollow portions of base plates for supplying the cooling medium.