MUTUAL INlKCr.lSCI-. IX ir./l/; lll.n.RS 



K7 



I'uv-'I'frmiual Equivalent Meilies. A list of r(nii\.ilfni two icrmiii.il 

 riMitance im-shrs, tliic lo Zolu-I, has hvvn n'wvn in l"\n. 17. All of tlic 

 tiuslics in I-i^s- l~ii, C ami H CDiitain two indurtaiicc elements. 

 Mutual imiurtance may exist between any two inductive elements 

 without chanvjini; fundamentally the nature of the reactance meshes. 

 This means that when mutual inductance exists hetween two coils in 



(B) 



L, C, 



(c) (D) 



Fig. 28— Equivalent Two-Terminal Reactance Networks, Only One of Which 

 Contains Mutual Inductance 



any of these meshes, the mesh may he designed to be electrically 

 equivalent to, and consequently can be substituted for, a correspond- 

 ing mesh of the same type having no mutual inductance. 



For example, consider the mesh shown in Fig. 28A which is poten- 

 tially equivalent to the first reactance mesh of Fig. 17C and, conse- 

 quently, to the other three reactance meshes of the same figure. 

 The inductance elements L/ and Lj', together with the mutual in- 

 ductance M acting between them, may be represented by an equiva- 

 lent T network, as previously stated. The reactance mesh formed 

 by Li', Li, and M, together with its equivalent T and r forms, is 

 shown in Fig. 29. By means of the relations given in Figs. 29A and 

 B, it is possible to derive, from the structure of Fig. 28A, the equiva- 

 lent structure shown in Fig. 2SB. Likewise, from formulae (4.')) and 

 (46) for the equivalence of the two structures of Fig. 17B, the mesh of 

 Fig. 28C can be obtained from that of Fig. 28B. Furthermore, if the 

 two inductances shown in series in Fig. 28C are merged, it is again 

 possible, by means of the conversion formulae for the two meshes of 



