Systematic analysis of induction coil failures

Frequency affects the performance of the induction system and the coil life. While all electromagnetic properties are important and affects efficiency, longevity, and frequency selection of induction heaters, two of them have the most pronounced effect, electrical resistivity and magnetic permeability. There will be higher coil efficiency when the ratio of the workpiece diameter and current penetration depth is greater than four. When it is less than three, there will be an increase in coil copper losses and necessitates having greater coil water cooling. If water cooling is not sufficiently increased, premature coil failure could result due to copper overheating and degradation. This can be addressed by selecting an operating frequency that avoids eddy current cancellation and is based on current penetration depth at the end of heating.