540 



THE BELL SYSTEM TECHNICAL JOURNAL, MAY 1954 



o 



o 

 > 



o 

 < 



h- 

 z 

 o 

 o 



300 



TIME,t, IN 10"^ SECONDS 



Fig. 4 — Contact voltage transient with sustained arc on break of an inductive 

 circuit. Pd contacts in atmospheric air, E = 50 volts, L = 0.025 henry, R = 115 

 ohms, C = 20 X 10~'^ farad. Velocity of contact separation 40 cms/sec. 



tical purposes one may neglect the voltage drop time which is the initia- 

 tive period of the arc. For the circuit in Fig. lb, the current through the 

 arc is the summation of the main circuit current and the transient current 



from the l-c circuit. The transient current is (Vai — y)(T)^'%in ^'{Icf^. 



Fig. 7, (a) and (b), represent diagrammatically the voltage and current 

 transients for lumped and distributed circuits. In both cases the arc is 



300 



lU 

 < 



O 

 > 



o 



z 

 o 

 o 



500 

 TIME,t, IN 10"^ SECONDS 



Fig. 5 — Contact voltage transient with glow discharge on break of an inductive 

 circuit. Pd contacts in atmospheric air, E = bO volts, 700 ohms relay coil and C = 

 200 X 100~i2 farad. Velocit^y of contact separation = 40 cms/sec. 



