This part of IEC 60424 gives guidance on allowable limits of surface irregularities applicable to ring-cores in accordance with the relevant generic specification defined in IEC 60424-1. This standard is considered as a sectional specification useful in the negotiations between ferrite core manufacturers and customers about surface irregularities.
IEC 60424-4:2015 history
2015IEC 60424-4:2015 Ferrite cores - Guidelines on the limits of surface irregularities - Part 4: Ring-cores
2001IEC 60424-4:2001 Ferrite cores - Guide on the limits of surface irregularities - Part 4: Ring-cores