EVS-EN 60424-5:2009

This part of IEC 60424 gives guidance on allowable limits of surface irregularities applicable to planar-cores in accordance with the relevant generic specification defined in IEC 60424-1. The relations between the main dimensions of planar E-, ER- and EL-cores differ from those of standard cores. For example, the width of planar cores is larger while the total height is much smaller. Also the thickness of the legs is in most cases smaller than compared to standard cores. Therefore the concept of fixed reference dimensions to determine the length of crack limits yield crack lengths which are not acceptable for this type of core. This part of IEC 60424 follows another concept which relates the crack length to dimensions of the surface on which the crack occurs.