.SLOW KKLEASE RELAY DESIGN 



201 



given by the equation: 



; = 2'"«"'"0 + 2i)' 



(14) 



in which 6\^ = x/A, the vahie of 6\o which would apply it' the .spherical 

 radiu.s were infinite, and both mating area.s plane. On .substituting this 

 expression for (Rg in (13), there is obtained the following e(]uation for 

 the pull at a domed pole face: 



F = 



StA 



mo 



(R 



27r/?(R„ 



1 + 2ir72«, 



(15) 



The right hand side of (14), and the expression given by (15) for the 

 ratio of F to <p^/(STrA) are both functions of a single dimcnsionless 

 parameter: R(R^ . These two ratios are plotted against this parameter in 

 Fig. 10. These curves show how the reluctance and pull values compare 



= 2wR\n ( 1 + -~ ) 



Let: (R„ = - = 



(R, 

 (R. 



A iriaR)^ 



= 2TR6{Jn 1 + 



27r/?(R^ / 



Pull for Flux <p 



V^ d(R(; 



Sir dx 



^ d(S{.G 

 Sir/t d(R„ 



_ J^ X l^-"V X - 



27r7?(R. 



.Jl 



x+h 



A-77(a;R) 



+ 27r7?(R„ 



Fig. 9 — Reluctance and pull of a domed i)ole face. 



