314 



BELL SYSTEM TECHNICAL JOURNAL 



Feeder-Rail, Trolley-Rail Base 



A'. Actual Network Connections 



i 1 A4T-R 



B' . Equivalent Network for Trolley-Rail Short Circuits 

 I , 



/z'ip:ip + 0-v')Z|2:34 



Z \a:7>a 



0-v')(z;2:i2-z;2:34) 



T 



Zl4:24=Z'-v'(l-v')Cz'|2:i2-Z[2:34)+(l-v')^CZ34-.34-Z|2:34) 



C. Equivalent Netzvork for Feeder-Rail Short Circuits 



v'(Z|2:i2-Zi2:34) 



Z|3:23 



I-V')Z'|2:I2+^'Z'|2:34 



T 



Z;3:23 = Z'-V'0-V')(ZI2:|2-Z;2:34)+^1^'.>^(Z34:34-Z;2:34) 

 Fig. 4 — Continued from page 34:6. 



driving-point impedance between terminals 1, 2 and the transfer 

 impedance to terminals 3, 4 for the'network shown on Fig. lA may be 

 formulated immediately as: 



Zi2:12 = (1 + il:n)Z'^, 

 Zi2:34 = - t„:12Z<"). 



(14) 



The positive sense for currents inn and 4;i2 is taken as indicated on 

 Fig. lA, namely, in the direction from terminal 2 to terminal 4 on 

 side 2. 



From the voltage equation around the loop formed from sides 1 and 2 

 in their entirety and the terminal shunt impedances, the difiference of 

 these impedances may be expressed by: 



Zi2:12 - Zi2:34 = - E (^l^^) + Z^^''^ - 2Z n^'^)i,..n. (15) 



4=1 



