IEC 60205-2009 pdf Calculation of the effective parameters of magnetic piece parts

1 Scope This International Standard lays down uniform rules for the calculation of the effective parameters of closed circuits of ferromagnetic material.
2 Basic rules The following basic rules are applicable to this standard. 2.1 All results shall be expressed in units based on the millimetre, shall be accurate to three significant figures, but to derive l e , A e , and V e the values of C 1 and C 2 shall be calculated to five significant figures. All angles are in radians. NOTE The purpose of specifying this degree of accuracy is only to ensure that parameters calculated at different establishments are identical and it is not intended to imply that the parameters are capable of being determined to this accuracy. 2.2 A min is the nominal value of the smallest cross-section. All the dimensions used to calculate A min shall be the mean values between the tolerance limits quoted on the appropriate piece part drawing. 2.3 2.4 Calculations are only applicable to the component parts of a closed magnetic circuit. All dimensions used for the purpose of calculations shall be the mean value within the tolerance limits quoted on the appropriate piece part drawing. 2.5 All irregularities in the outline of the core, such as small cut-outs, notches, chamfers, etc. shall be ignored unless otherwise described. 2.6 When the calculation involves the sharp corner of a piece part, then the mean length of flux path for that corner shall be taken as the mean circular path joining the centres of area of the two adjacent uniform sections, and the cross-sectional area associated with that length shall be taken as the average area of the two adjacent uniform sections.