ECONOMICS OF TELEPHONE RELAY APPLICATIONS 



243 



rlcr 



10 10^ 10-^ 



COIL RESISTANCE, R, IN OHMS 



Figs. 10 and 11 — K^ and NI values versus resistance for various wire gauges 

 for a typical relay. 



COST WHEN OPTIMUM RESISTANCE CONDITION IS NOT SATISFIED 



There will, of course, be cases in practice where the optimum re- 

 sistance is not used, for such reasons as standardizing of certain coil 

 sizes, need for speed, or insufficient winding space. The penalty in cost 

 from departing from the ideal winding size may be found by comparing 

 the cost for any value of resistance, (cfiuation 21), with the cost if re- 

 sistance were optimum, (equation 23): 



C _ Kx/R + K2R 



Co " 



2 \R "^ 7?„ 



(24) 



