ESTIMATIOX AXD COXTKOL OF ( JPKKATK TIMK OF RELAYS 



l()5 



0.25 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.5 2 2.5 3 3.5 



RATIO OF VARIABLE TO NOMINAL VALUE 



Fig. 9 — Mass controlled operate time variations. 



relay always must operate. However, the purpose of these variation 

 curves is to adjust measured data. The coil constant is the independent 

 variable in any measurement and can always be set exactly. Hence it 

 does not reciuire an adjustment. 



The chart shows clearly that the single most important factor is the 

 armature travel. Following are power W , and leakage reluctance (R^ . 

 The least sensitive is the pole face area .4, because it has been optimized 

 in the design. Taking the slopes at the (1, 1) point, the operate time, 

 expressed in a separated variable form, becomes: 



0.66 



F\ 



(Ro m 



0.21^.084^.056 



.4^ 



IfO -4561 0.33^.084 



(28) 



The exponents are a measure of sensitivity — the nearer they ap- 

 proach zero, the less the sensitivity. In designing electromagnets for 

 speed, every effort should be made to keep the armature travel to a 

 minimum as it is outstanding in its effect on time. 



For our present purpose, the chart is used to adjust measured operate 

 time data to the average value. The factors to be corrected are Fi , 

 m, Xi , ^3 , A, (Ro , (Rl , i.e., all the pertinent geometric and load factors 

 shown in Fig. 7. This completes the description of the method used for 

 establishing the average mass controlled operate time curves. 



