LINE CURRENT REGULATION 629 



and the expressions for the ratios of the received currents to corre- 

 sponding line currents, /i, I2 and I3 are: 



il = a(l/2r+ri) .^. 

 /i (r+ri) {2a + b)+ab 



i, i?,(l/2r+r2) ^5) 



/2 {r+r2){2Ro + b)+R-:h 

 H a{l/2T+r,) 



(6) 



/3 (i?3+r+r3) (2a+6)+a6 

 where, 



a, represents the constant resistance of each bridge arm in ar- 



rangements (1) and (3); 



b, the resistance of the receiving relay; 



£, the voltage of the line battery which is assumed to be equal at 

 both stations and may be either negative or positive; 



G, the constant resistance in series with the line battery taps in 

 arrangements (2) and (3) ; 



T, the resistance of the line between the duplex sets. 



i?i, R2 and Rz are the regulating resistances in the different locations 

 corresponding to the subscripts. In the equations for arrangement 

 (1), G is assumed to be contained in Ri and in the equations for 

 arrangement (2), a is assumed to be contained in R^. The equations 

 for the parameters, ri, r^ and rz are as follows: 



.. = ^17-+Gr+g ^-+^-^^-+^^^ -|r (8) 



r^= ^\T- + GT+Rz{T+Rz + 2G)^- 



2aRz{a + b)-{-aT{a-\-b)-j-ab(a-\-2G) 



2a-\-b 



-hT (9) 



While the line current and the received current can be calculated for 

 any values of R and T from equations (1) to (9) inclusive, explicit line 

 current equations are needed for calculating the received current for a 

 definite value of line current, such as shown by curves ii, U and h, 

 Fig. 2. It is clear that these curves cannot be calculated from equa- 



