LJGIITXLXG PROTECT ION OF BL'RIED TOLL CABLE 



265 



g(0',t) 



10 



20 



50 100 200 



t - Microseconds 



500 



1000 



r--"(^)'-"" 



Figure 4 — Function g{a , I) = I Jit 



Jo 

 J{1) = /(e-" - c^'") 

 a = 1.3 -10^ 6 = 5-10* / = 1150 amperes 



and 



Fo(.r, /) 



Ra^ 



fg(a'.v, /) - ^(^\r,/)] 



(27) 



2(a - /J) 



In Fig. 5 the crest values of l'(-v, /) and Fo(x, /), calculated for the cable 

 considered before, are plotted against .v, together with those observed in 

 the tests. When the voltage l'(0, t) at the point where current enters the 

 sheath is great enough to break down the insulation of a core conductor, the 



