ESTIAIATIOX AXD COXTKOL OF OPKKATK TIMK OF HKLAYS 



IGl 



5 6000 



9-4000 



LL 3000 



^J ^ \ \ \ \ \ 



1 2 3 4 5 6 7 8 9 10 11 12 13 



TIME,t, IN MILLISECONDS 



Fig. 8 — General character of winding flux and armature force rise. 



the pole face gap flux as given by (17). Hence, the initial force rise will 

 be parabolic, as shown by the lower portion of the curves of Fig. 8. 

 After a long enough time however, the flux will have reached its maxi- 

 mum and the finally developed force will be constant with time. This is 

 shown by the force curves approaching horizontal lines to the right in 

 the same force diagram. As the force curve is continuous, there also 

 must be an inflection point in the curve, and the entire curve has the 

 general shape as shown. 



The waiting time ^i occurs while the magnetic force builds up to Fx , as 

 indicated, amounting to 2 millisec for the example shown. This time 

 generally includes all of the parabolic part of the curve. Following the 

 waiting time, the initial force l)uild-up necessarily is almost linear be- 



