SLOW llELEASE KELAY DESIGN 



193 



2400 



R 1600 



5 



X 1400 



O 



HI 



Z 1200 

 1000 



600 



0.5 



3.0 



1.0 1.5 2.0 2.5 



ABAMPERE-TURNS^ NI 



Fig. 4 — Release time versus ampere turns. 



for which (p = for fF + [Fc = 0, while tp" is the asymptote approached 

 by ^ as J is increased. (R" is the initial incremental reluctance, the value 

 of d'S/dif for <p = 0. If (po, as in Fig. 1, is the value of (p for fF =^ 0, the 

 resulting expression for 3^c may be substituted in (3) and this equation 

 written in the alternative form: 



'5 



<P 



<Po 



(4) 



Oi'f II II II 



Ky\. ip (p — (p ip — (pQ 



The incremental reluctance (R,, the value of d'^/d<p at v' = Vo , is given 

 by: 



(R, = (^/^)\:\ (5) 



^ 



(po 



The expression for 9'/(47r) gi\-en by (4) maj^ be substituted for Ni in 

 (2) to give an expression for the release time t. After clearing fractions, 

 the resulting efjuation is: 



t _ 4:ir{(p — cpo) 

 G ~ 



(W'ip"^ J^ \<p" — (pa ^ — <Pq/ 



d<p. 



