BS EN 60205-2017 pdf free download.Calculation of the effective parameters of magnetic piece parts This document specifies uniform rules for the calculation of the effective parameters of closed circuits of ferromagnetic material.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
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4 Basic rules applicable to this standard
4.1 All results shall be expressed in units based on millimetres, 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.
4.2 A min is the nominal value of the smallest cross-section. A g is the geometrical crosssection of a ring core with rectangular shape. All the dimensions used to calculate A min shall be the mean values between the tolerance limits quoted on the appropriate piece part drawing. All results shall be expressed in units based on millimetres, and shall be accurate to three significant figures.
The minimum physical cross-section area A min is given as: A min = min (A i )
NOTE A g to be used for the measurement of the saturation flux density B max on ring cores with rectangular crosssection.
4.3 Calculations are only applicable to the component parts of a closed magnetic circuit.
4.4 All dimensions used for the purpose of calculations shall be the mean value within the tolerance limits quoted on the appropriate piece part drawing.
4.5 All irregularities in the outline of the core, such as small cut-outs, notches, chamfers, etc.
shall be ignored unless otherwise described.
4.6 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.
Calculation of effective parameters l e , A e and V e .
The effective parameters can be defined as
where
l e is the effective magnetic length of the core (mm);
A e is the effective cross-sectional area (mm 2 );
V e is the effective volume (mm 3 );
C 1 is the core constant (mm −1 );
C 2 is the core constant (mm −3 ).
5 Formulae for the various types of cores
5.1 Ring cores
5.1 .1 Ring cores in general
Drawings of ring cores are shown in Figure 1 .
When the winding is uniformly distributed over a ring core, it may be expected that, at all points inside the ring core, the flux lines will be parallel to its surface.
No leakage flux will therefore leave or enter the ring core. This justifies the use of a theoretically more correct derivation of the effective parameters, which does not make use of the assumption that the flux is uniformly distributed over the cross-section.BS EN 60205 pdf download