High current power inductors are usually used in high power applications which flow relatively high current through, so there are strict requirements for the effective cross-sectional area of wire and DCR.

The effective cross-sectional area of the round enameled wire is smaller than that of the flat wire. There is a gap between the turns of the round wire, and the utilizations of the winding window of the magnetic-core insufficient. Therefore, with the same size, the current capacity of the round enameled wire product is smaller than that of the flat wire, and there will be a problem of temperature rise. That is why engineers design high current power inductor with flat wire, not round wire.