238 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1954 



quence, then the vahie per relay of one milHsecond is 



WaJ) WaJ) 



= 1^ , Mi etc., for path B, (20) 



WbJ) WboV 



= — , in general, (dollars per millisecond). 



wp 



These eciuations give the general expression for the value of functioning 

 time in terms of cost. They permit the direct comparison with cost of a 

 relay design, including its coding cost, manufacturing cost, or power 

 drain cost, in deciding on how much investment is warranted in switch- 

 ing apparatus in order to shorten the marker work time. 



1 .43 Simple Examples of Relay Design for Speed 



The above relations make it possible to rapidly evaluate design changes 

 for speeding up relaj^s, or to state the value of seeking a design change 

 that will make speed possible. Several examples will be given. 



(a) Relay Involved in a Major Event 



Suppose the following^ typical conditions are given: 



No. of markers per line = p = 0.0006. 



Path factor = g = 1. 



Relays per marker function = w = 1 . 



Value per millisecond per line = Ct = SO. 04. 



Then value per millisecond per relay is 



^ 004 X 1 ^ 

 0.0006 X 1 



In this case a very large investment per relay could be justified in order 

 to gain small savings in time. 



(6) Relay Involved in a Suhevent 



Suppose the following tj^pical conditions are gi\-en: 



No. of markers per line = p = 0.0006. 



Path factor = q = % = 0.25. 



