Effective resistance to alternating currents of multilayer windings

E. Weber (Polytechnic Institute of Brooklyn, Brooklyn, N. Y.): The most important result of the very valuable contribution of the authors is their figure 4 which demonstrates the need for careful design of windings, particularly at higher frequencies. As shown in one example, an increase of copper thickness, although decreasing the d-c resistance, increases the a-c effective resistance considerably more than proportionally, so that instead of obtaining lower losses with more copper, one thus obtains very much higher losses with the attending problem of heat dissipation. With the data of this paper available, it is now possible to design strip copper windings for higher frequencies which give the lowest losses with a minimum of copper weight; that is, the most economical winding for each individual case.