Analysis of Measured Magnetization 

 and Pull Cliaracteristics 



|{y K. L. PI-:KK, Jr. 



(M;inuscri|)t received Sept einher 21,M953) 



// is shoint in this article thai the observed magnetization relations of 

 most ordinary electroniagnets conform to simple expressions which can be 

 interpreted as the Jinx vs. magnetomotive force equations of a reluctance 

 network, analogous to the current-voltage equations of a resistance network. 

 To the extent of such conform it g the magnetic circuit constants characterizing 

 the network suffice for the evaluation of the field energy and pull charac- 

 teristics of the electromagnet. The agreement between the observed mag- 

 ndization and these simple relations is close in the region of linear mag- 

 netization, and is adequate for engineering purposes at higher flux densities, 

 but the extent of agreement in the latter range varies with the type of struc- 

 ture and the location of the magnetic parts which first approach saturation. 



Specijlc analytical and graphical procedures are given for the evaluation 

 of the magnetic circuit constants from both pull and magnetization measure- 

 ments. These procedures employ relations which give linear plots indicating 

 the degree of conformity of the observed relations to the expressions used to 

 fit them. The relation of the measured constants to those which can be esti- 

 mated in design is discussed, as is the use and application of the measured 

 constants in development and engineering studies. 



1 INTRODUCTION 



In the design of telephone relays and similar switching apparatus, the 

 characteristics of the electromagnet which serves as motor element may 

 Ije distinguished from those of the mechanical system of contact springs 

 and actuating members which it operates. The performance of the elec- 

 tromagnet is characterized statically by the mechanical work done for a 

 given coil energization, and dynamically by the time recjuired to actuate 

 the mechanical load, including in this the inertia of the moving parts. 



Both the potential work output of the electromagnet and the energy 

 stored in de\-eloping its field can be evaluated from its magnetization 



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