IEC 63182-2:2020 specifies the dimensions that are of importance for mechanical interchangeability for a preferred range of ring-cores (also called toroids) made of magnetic powder, the effective parameter values to be used in calculations involving them, and gives guidelines on allowable limits of surface irregularities applicable to coated ring-cores.
The selection of core sizes for this document is based on the philosophy of including those sizes which are industrial standards, meaning that they are in broad-based use within the industry. This document is considered as a sectional specification useful in the negotiations between magnetic powder core manufacturers and users about surface irregularities.