142 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1954 



Tho olTect of the magnetic drag on the motion time is apparent in the 

 curves of Fig. 10. The motion timc^ for a given vahie of n increases as 

 tin/tE decreases, corresponding to increascnl drag. Thus a reduction in 

 reliound ])y increased magnetic drag is, of course, accompaniedbyaionger 

 motion time. It is of interest to note that the increasing acceleration 

 resuhf^ in an armature displacement which varies as the culx^ of the 

 time, as in the relation applying in operate. 



The results shown are for the case (\^ = 5. For Cl = 3, corresponding 

 to higher leakage, the results are similar, but the drag ratio W/V values 

 are from 5 to 10 per cent lower than those for Cl = 5, and the values 

 of I/Im are correspondingly smaller. Thus the value of Cl applying has 

 only a secondary effect on the release motion. 



While these results are formally limited to the special case of a con- 

 stant retractile force, the conclusions are of broader application. A load 

 curve that decreases as the gap opens modifies the solution for the same 

 operated load Fo only in reducing the net accelerating force, increasing 

 the drag ratio and the motion time. The residual magnetism, neglected 

 in this discussion, has a similar, and minor, effect. The results show Cl 

 to have little effect on the motion, which is governed primarily by the 

 values of u and Im/Ie applying. 



0.5 

 0.4 



0.03 



0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 



W 

 V 



Fig. 11 - Energy absorlx-d by niagiiolic drag in release motion. 



