GB1233955A - - Google Patents

Abstract

1,233,955. Substation circuits; line balancing networks. SOC. ITALIANA TELECOMUNICAZIONI SIEMENS S.p.A. 11 Oct., 1968 [23 Oct., 1967], No. 48298/68. Headings H4K and H4R. A subset incorporating a hybrid transformer is matched to line by means of a capacitive network such that the reactance of the set plus network is a minimum at the high frequency end of the speech band. The normal characteristics of a subset and a line are depicted in Fig. 1 where curves 1, I<SP>1</SP> and 2, 2<SP>1</SP> indicate the characteristics with respect to frequency of the resistive and reactive components of lines using 26 and 22 gauge conductors respectively and Ra, jxa indicate the similar characteristics for a set. A mathematical discussion shows that by capacitively loading the essentially inductive set a good match with an essentially capacitive line can be obtained in respect of both resistive and reactive components. Fig. 2 shows the improved characteristics obtained by using a parallel RC network across the line and the remaining Figures (not shown) indicate the similar improvements obtained by using: a single shunt capacitor; a series RC network in shunt with the line; a parallel RC network in series with a capacitor across the line; a capacitor in shunt with transformer winding I or transformer windings I and III (Figs. 6, 7, not shown); a capacitor or a resistor in shunt with the line and another capacitor in shunt with winding I; and a series RC network across the line with a capacitor in shunt with winding I (Fig. 10, not shown).