ELECTRICAL EQUIPMENT 



magnetic field, the value of the total current at the end of the line 



being equal to 2i, Fig. 382. 



The wave travels twice forth and back over the entire length 



of the line, after which the 

 conditions return to the 

 same state as at the begin- 

 ning, Fig. 383. It will, how- 

 ever, continue to oscillate 

 forth and back until 

 damped out by the resist- 

 ance and leakage of the 

 line, after which it assumes 

 a stationary condition with 

 a charge corresponding to 

 the voltage of the generator. 

 The wave length, or 

 rather the distance which 

 the wave front travels in 

 completing the above cycle, 

 is obviously equal to four 

 times the length of the line, 

 and the frequency of the 

 oscillation is 



HI 



$ 



"T 



FIG. 383. One Complete Oscillation of a 



where I is the length of the 



line, and v or = the 

 VLC 



velocity at which electric 

 energy travels through a 

 circuit whose inductance 

 and capacity per unit 



This 



Traveling Wave Set Up when Switching length are L and C. 



in an Open-oircuited Line. velocity for overhead lines 



is equal to the velocity of 



light, or 188,000 miles per second. The waves in the above illus- 

 trations are shown of a rectangular form which could only be 

 the case if the generators had no resistance or inductance. Ordi- 

 narily, however, they are of a more or less sloping character. 



