ESTIMATION AND C'ONTllOL OF Ol'KK A TK I'lMK OK KKl^AYS 



J71 



Solving 



RiK = 



2Ri + R2 



2 + 



iW 



(32) 



/?2K = 2 ( R, + ^' - RlE 



Because the equivalent coil constants have the same ratio as the e(iui\'a- 

 lent resistances, the voltage division will be: 



l^iE — 



RieEo 



Ri + 



Ri 



(33) 



With these, the equivalent coil constants and powers can be computed 

 and charts such as Fig. 6 used as before. 



Selection of Optimum Coils, Identical Structures 



Neither Winding Known, Operate Times Given 



In the above discussions it was assumed that the windings were known 

 and that the operate time data were sought. The procedure can be re- 

 versed, starting with a desired operate time, or times, and then choosing 

 optimum coils. From time curves such as Fig. 6, the watts corresponding 

 to the desired times can be obtained pro^'ided thej^ are read from the 

 same coil constant vertical because the same current flows through 

 both and hence the effective coil constants necessarily must l)e eciual. 



E,E 



^ E2E — * 



— Wv — ^M^P — 



N, R,E 



^^WP — VW— R^E N2 



— \AA — ^"SM^ — 

 Fig. 10 — Transformation of series-parallel rela}' circuit. 



