US1663730A - Electric connection - Google Patents

Description

March 27, 1928.

C. L. M. RAVUT ELECTRIC CONNECTION Filed July 8. 1924 2 Sheets-Sheet 1 C. L. M. RAVUT ELECTRIC CONNECTION Filed Jul v 8, 1924 2 Sheets-Sheet 2 k-- I 0 I Kr munication circuits which are independent v with the double pair grouping, while on the.

other hand the second class clrcuits Wlll be Patented Mar. 2?, 1928..

warren s rates marina a CAMILLE Louis MARIE we, ermine- RANCE, AssIGnon. mosoo'ln'rn INDUS- TRIELLE DES rnLnrnonns (CONSTRUCTIONS nLnc'rRIQUEs, oeou'ronouo, CABLES),

OF PARIS, FRANCE.

ELECTRIC connncrron.

Application filed July 8, 1924, Serial No. 724,870, andjin France February 28, 1924.

. The present invention relates to a system of electric connections, chiefly apphcable to long-distance telephony, in whlch the wires like communication, and with the -.use of a triple three-wire circuit we are enabled to provide a combination or phantom threewire circuit comprising two additional comof each other and independent of the communication circuitsoflered by each of the component three-wire physical circuits. In

this manner, the wires are more efficiently employed than in the known system. Taking as an example a group of72 conductors-to facilitate the calculations-,-if the conductors are disposed in double pairs they I will constitute 18 double pairs and will hence altord 36 physical communicatlon circuits of the usual type or of the first class,

as well as 18 phantom communication circuits, or circuits of the second c-lassb But if the said conductors are disposed as triple three-wire circuits, they will form8' triple three-wire circuits, i. e. 3 8=21 physical three-wire circuits providing 2 2l=48 communication lines of the first class, while the phantom circuits will afford 2 8=16 coinmunication circuits of the sec'ondclass.

By my arrangement of the conductors in triple three-wire sets, we are thus enabled to provide 4836=12 effective circuits of the first class in addition to what is obtained diminished by 1816=2 circuits. However the total gain will be (&8+16) (36+ mented by about 20 percent by my said arrangement. 1

' The characteristics of the telephone communications of the first class are identical within the limits of uniformity of the electric constants of the several conductors of *the setbut differ from the characteristics ofthe conductors of the second class.

The following description, together with the appended drawings which are given by way of example, sets forth my saidinv ention. a Figs 1 and 2 show respectivelyin cross section and in elevation the three conductors V forming a three-wire set.

V Fig; 3 represents aline circuit. Fig. 4: is a diagram of a complete installation. V V

Fig. 5 is a diagram of the arrangement of circuits atthe ends of the line.

Fig. 6 shows a line employing a triple three-wire set.

In the system according to the present in vention, the wires are disposed in three-wire sets and in triple three-wire sets. understood that the three wires of a' set-have an identicalconstruction and insulation, and

they are moreover formed 'into a cable strand of the three-wire'type, the three in- It is' sulated conductors being juxtaposed and twisted in'helical form around a common geometric axis, in such manner that the centres of the three conductors upon a plane perpendicular to the cable axis shall repre sent the three vertices of an equilateral triangle. Figs. 1 and a. WVheu this arrange ment is to be tripled, each of the constituent three-wire sets is considered as a single conrluctor, and the preceding remarks will be equally applicable. By the useof adequate arrangements at the ends of the line, in accordance with certain conditions to be hereinafter setfltorth, the independent circuits can be'properly separated. i

-The present invention, although 7 chiefly applicable to telephone cables, is independ"- ent of the nature of the conductors and the insulation, and relates to sets of overhead line wires as well as'to conductors in the form of cables, and the conditions can be transposed in an immediate manner.

Considering in the first place a single set of three conductors, the three wires are identical and are geometrically situated in conditions of symmetry such that their relative position in pairs is always the same.

Let R be the resistance of each Wire per unit length.

L the coetficient of self-induction of each wire per unit length.

C the capacity of each wire per unit length relative to the sheathin spectively between a wire and the set, and between one Wire and another; per unit length. '0 e 0 the potentialof each wire at the distance at from the initial or Zero point.

71, '5 i the current in each wire at the distance as from the zero point. p For the distance a: from the Zero point,

the equations of propagation will be:v

M the coefficient of mutuaTinduction of (1) -g =Mi R+L)i +1\/I i any two wires oi the set, per unit length. m t r at C the capacity of any two wires relative L to each other, per unit of length. 5:13 575 at G and G the losses per unit length reand e +2e co-mm la{mega-(meg 5' 6 2 ;=-(e+c v (G +2G)+(C +2C)%IQJ G+C QJ a a a a (o tc ael-o )a+l c +ze o wm j If we desi nate by oz and 1x the two imagi- 6 6 nary cube Toots of unity, and by x )I A i x =p. =q. four numerical coelfi- 3 5 cients which can be temporarily given any x :[3G+G0+ G o) g j i desired value, and are subjected solely to the condition a ag A2/1#O, or what is the same, (3) pq#O We can at once substitute for the six equations (1) and (2) the three pairs of equations:

defined by the equations The equations (4) characterize the propagation of the potential 1) and the current 1 2 along a line consisting of two wlres of the three-wire set in series, the third wire being separate. The equations (5) characterize the propagation of the potential 0, and the current t, alongan identical line. These The equivalence of the equations ('1) and (2) on the one hand and of the three pairs of equations (4) (5) (6) on the other hand, shows that the real propagation of potentials and currents 12 ,42 0 2' i 46 in the three Wires of the set is equivalent to the superposition of three virtual propagations of an independent nature which have been above specified.

Since the imaginary cube roots of unity have introduced the symbol 1, it will be henceforth supposed that the considerations will bear upon potentials and currents which are functions of the time and have the form A. e it being understood that finally, by retaining only the real portions, for instance,

and not departing from linear relations be-' the, three wires of the set, by two pairs of terminals A A 1 A A' to two independent sources of current, and by the last terminal A to a third source of current whose other pole is grounded; this disposition has the following particular features:

1. The source of current connected at A A 1 only intervenes in the value of the line potentials and currents by modifying the value of the potential 22, and the current 7/ A A 2 acts only upon the combinations 2),, and i of the line potentials and currents.

3. The source of current connected at A acts only upon the combinations v +v +12 and Since the nature of v i 1),, i will depend upon the arbitrary values X, p, q, a great variety of dispositions can be employed, according to the values which are selected for these four factors, it being however stipulated that 1) must be other than g. It can be readily demonstrated that p+q should have a zero-value. We niay likewise determine the conditions to be complied with by an arrangement comprising three outgoing terminals B B B and two pairs of incoming terminals A A A A; with an additional incoming terminal A in order to possess the above mentioned properties. We will indicate the required conditions and show how these are obtained. In this case it is understood that if a disposition comprising the above-mentioned incoming and outgoing terminals complies with the conditions to be hereinafter set forth' which can be shown by experimentthe values A a p q (real or imaginary) will exist, by means of which we may set out potentials and currents 12, i 0,13,, in accordance'with the formulae (7), in such manner that the action will takeplace as if the source of current connected at A A 1 acted directly upon the potential 1), and the current; i the source connected at A A upon the potential 12,,

and the currenti and the source con- 22 +12 nected at A upon the potential and the current "i +i +i I If we connect two identical arrangements to the two ends of the line (Fig. 4), the

2. The source of current connected atdistributed in three groups.

lent, and will act at'the receiving end upon did not exist. A like action will take place between A A; and C U and between A and C We thus obtain on. the threewire set three entirely separate communications. i

Since the potentials and currents a g i,

1 r or v, 5 t, are each propagated along a line similar to what would be constituted by two wires of the three-wire se t-thethird wire being isolated it will be observed that whatever may be the values of A ,u. p q, the sole fact that the terminal circuits comply with the conditions to be hereinafter set forth implies the obtainment of three independent communications.

We will briefly indicate the method of attaining the condition 1) q =0, and the conditions stipulated for the terminal circuits.

Let 2'2 22 22 (Fig. 4) be the potentials of the three terminals B1 B2 B516 m the potential differences applied between the terminals A and A 1 and between the terminals A A and u the potential applied to the terminal '65 C C for instance, as if the other receivers,

A j jg j are the currents from the terminal 1 potentials. 7

We will take as a starting point the general theory indicated by M. IC. Ravut in the Revue Gnrale delElectricite, vol. XIV, N0. 17. This theory shows that in a circulation network having 8 poles or terminals connected by connecting currents with out-,

arrangement which maintain the various side sources of supply, if the said-poles constitute n groups in such manner that in each group the connecting currents have a simple relation such as a linear relation, there will exist a function, quadratic, homogeneous and of the second degree, H, of the connectingcurrents of the other s-n poles,"su ch that thehalf-derivative of this function H relative to one of these s-n connecting currents shall be equal to the difference of potential between the corresponding pole and areference pole chosen fromeach of the it groups.

The terminal disposition here considered is in fact, a network having 8' terminals 1. The group B B B whereof ence pole is the pole A thecurrents being poles being a reference pole, the currents being 1' and j in such manner that .3. The group A A one of these two poles being a reference pole, thecurrents being 3: and -j in such 'manner that the refer- 4 i i and j in such manner that i +i i i l 2. The group A A one of these two a quadratic function. of five currents i i i 3 jg, for instance. I

The equation 12 (7):; 04 22 E (v -u aha-a a (22 u permits the formation of the linear functions (7) 12 i v, '5 depending upon the second members of the first three equations (9).

We then substitute in the first three equa c d Cgdg and we also find whence: p q 0, these latter equations be ing compatible with the equations (10).

If a given arrangement complies with the conditions (10) we find for e i 7), i the Values 7),, /1 ((1 11 (Z202 (lg U n I i' l z' z a s) and n being coefiicients of proportionality which are not defined, the .c and the d being the coeflicients of the characteristic H of the arrangement.

By reason of the first conditions (10), e t 1) i will in fact have the form indicated in the equations (7), and the problem is solved wherein we act individually by the 8 sources upon potentials and currents propagated over the three-wire set according to the equations (4) (5) and (6).

The coefficients a; b, c, d of the function H (which are homogeneous with impedances) may be calculated according to the diagram of circuits; they may also be measured upon an arrangement which is constituted in order toascertain whether the conditions (10) have been properly carried out.

We may provide aphysical expression of the conditions (10) by returning to the equations (9). We can readily verify whether these conditions (10) are equivalent to the following:

1. Condition b =O.The two outer circuits A A and A A should beindependent of each other after the manner of the two diagonals of a balanced Wheatstone bridge, when the outer terminals B B B are isolated.

2. Conditions c +c +c =O and d +d d =O.lf a potential difference it is used between the terminals A A the sum of the potential differences between each outer terminal B 1 2 B and the supplementary terminal A should be null, and irrespectively of the value of the external impedance inserted between the terminals A and A The same is true if in the preceding case we use A A g instead of A A or A A instead of A A 3. Conditions a (r (1 (r (L33 (1 If We isolate the four terminals A Ai A A g and use between each terminal B B B and the terminal A potential differences whose sum is zero (e. g. three potential differences on the V three-phase system) the current traversing the supplementary terminal A should be null.

a m 21 21, 2 2 e 0 d 0 d c 11 Since the terminals A A A A and B B are isolated a current i is caused to enter at the terminal B and to leave at the terminal A It produces between A and A a potential difference u between A and A g a potential difference a and between B and- ]3 a potential difference v t We deter mine the fourth proportional factor if) for these three potential differences. If wenow treat the three terminals B B B by circular permutation, while maintaining a constant value for the current i, this fourth factor should remain constant in the three measurements. In this case as well as in the rest of my exposition, the potentials are considered in the vector form 22=Ve 6 being the phase of v with respect to an initial point which is of an arbitrary nature.

5. Condition 0 cZ,+c c +d d =0.This condition is satisfied when the conditions specified in the preceding paragraph are 4. Conditions satisfied. The independence of the communications exchanged between A A, and C C on the other hand, between A A and C C on the other hand, and further, between A and C will prevail irrespectively of the variations in the as, bs, cs and ds relative to the pulsation, at least for all pulsations for which the conditions are complied with; but in this case the potentials and currents 22 i and 2),, i, which are propagated individually over the three-wire set are differently compounded, according to the frequencies, with the potentials and currents of the For this reason one of the communications will be entirely confused and unintelligible upon the Whole length of the line connecting the end outfits, although it will be veryvclear and without confusion between the corresponding outfits; 'The whole action will take place as if the various pulsations concerned in the telephone comground. munication became separated in the connecting arrangement at the transmitting end and were separately distributed, each in its own manner, upon the three wires of the set between the outfits at each end,then coming together in an accurate manner in the connecting arrangement at the receiving endexcept for any distortion which may be due to the length of the three-Wire line. V

cal connectingthree wires of the set.

As an example of a practl arrangement, we will describe the a ment which is illustrated in Fig. 5. transformer in which the middle part of the secondary is accessible, this being analogous to a coil of the telegraphic type which is in current use for two-Wire telephone circuits; T is a transformer of. the usual type with T T 3 T are three. similar ch is provided with two windings.

transformers each of whi two windings.

The primary W1 T1 is a a a (1 rrangendings of'thetransformers T T' T are disposed on the star system about a central point which is connected to the external incoming terminal A primary windings are each connected to one The said of the three outgoing terminals 13, B B to which are connected the ends of the three wires of the telephone line. r

The secondary windings of the transformers T T .T are also disposed on the star system about an isolated central point. Further, the secondaries Nos. 1 and 2, corresponding to the outgoing terminals B and B are each connected tov one end of the secondary of the transformer T The middle point of the secondary of T is connected to the outgoing end of the secondary No. 3 of the group T T 3 T corresponding to the terminal B through the secondary of the transformer T The primary of T is connected to the two incoming terminals A A and the primary of T to the two incoming terminals A A The sources of current are disposed as follows: (1) between A and A,, (2) betweenA and A (3) between A -and,

The following designations are employed: fZT the impedance 'ofthe primary circuit 0 I fgfZ' the total impedance of the secondary O I y ZM the mutual induction between the primary of T .and the entire secondary.

M the mutual induction between the two halves of the secondary of T Y Z the impedance of the prirnary of T Z 'the impedance of thev secondary of T M the mutual induction between the two windings of T J Z the impedance of theprimary of T T or T Z the impedance T3, T;;' 01 TH3. i l

' M the mutual induction between the two windings of T T or T If we employ Kirchoffs equations for this system, and if we seelrfori thecoeliicients a b c d of the characteristic-function H, we will find the followingequations by an easy calculation. a 1

of the secondary of The arrangement thus verifies the condi so that the compounding of 72 and v with tions (1 O).

2),, assume the simple forms In this particular case, 1)), and v v2 v -will not vary with the pulsation. The said arrangement verifies the conditions (10) irrespectively of. the pulsation 19g w, and it can thus be employed both for telephony and telegraphy. The preceding considerations will now be 1applied to the case of a triple three-wire inc. 7

1. We made use of three triple circuits of the type which has been above considered, these resembling each other as closely as possible.

2. The three triple circuits are also wound together in a cable, each being treated as a separate conductor of a three-wire circuit.

In these conditions We may make the following suppositions:

1. The resistance per unit length of any one of the nine wires of the three triple circuits is the same, this being represented by R. V

2. The self-induction of eachwire per unit length is also the same, this being represented by L. V 3. The mutual induction of the wires of any given three-wire set, taken in pairs, is the same (represented by -M) irrespectivoly of the three-wire set containing the same.

4. -The mutual induction of any two wires, one pertainingto a given three-wire set and the second to another three-wire set, is the same (M 5. The capacity of a pair of wires of a given three-wire set is the same (C) irrespectively of the three-wire set containing the said wires; the same is true for the conductance representing the losses (G).

6. The capacity of a pair of Wires whereof one pertains to a given threewire set and the second to another three-wire set is the same ((3') the same is true for the value of element of the length and the effect of the ohmic resistance as well as the electromiotive forces of induction, and in like manner for each wire, the equation evaluating the leakage current which leaves the conductors at each point, taking due account of the capacities and losses as well as the distribution of potential in the plane perpendicular to the centre line of the three triple circuits.

We will specify for each three-wire set the abovementioned potentials and currents e, i, 2),, i,,; in this case, the values of v 2),, and relative to a three-wire circuit comprise only the currents pertaining to this same circuit, so that all that has been stated for one three- 1 wire set concerning the propagations of v, i

and of 2),, 11,, will hold good. We will further specify 12 +v +v for each three-wire set,

and it is found that the equations giving (v +v +c for the three triple circuits do not contain the currents of the nine Wires in question, except by the combination i +i employed for each three-wire set. We thus postulate c +v +e =e for the first threewire set, 1/ for the second set, and 0' for the third set. In like manner, we have i +i +i =t or i or i for the three sets respectively; between the values of 1; and 'L, the equations have exactly the same form as the initial equations (1), and only the values of the coefiieients have changed.

For this reason we may consider the three additional incoming poles A A A of the arrangementsserving to connect each threewire set of the triple combination as forming the end of one of the wires of the phantom three-Wire circuit. In like manner at the other end, as concerns the. additionaloutgoing poles C C C the same conditions prevail. So that all that has been specified for the three-Wire circuit alone will now prevail for the phantom three-wire circuit, and the conditions (10) will apply to the end connecting arrangements for the phantom threewire circuit. But the optimum specification, i. e. the conditions to be complied with by the constants of the line will not be the same for the end connectingarrangements pertaining to the phantom three wire set as for the arrangements used with the physical three-wire sets.

With reference to the above-mentioned form of construction, Fig. 6 shows the end 160 connecting arrangements for a triple threewire set whose phantom three-wire circuit is utilized. The independent communications are as follows:

First three-wire set: V I A f 1 71th 011 0 1 A2 'A g XVl'lih C21 "21 Second three-wire set:

WI 2 k 2 I 2 1 '1 with 1 1 1 Phantom .circuits A}! 1 Wlbll C1: 1;

There will. also be an independent com- "Vitrh 02 3 2 'munication betweenA and C relatin to potential in each wire in the specification of 130- 1. A system of long distance telephonic or 'other electric communication comprising three insulated wires having an identical construction'and insulation, juxtaposed and twisted in helical form around a common geometric axis, in such manner that the centers of the three conductors upon a plane perpendicular to the twisting axis occupy the three vertices of an equilateral triangle, thus forming whatis called a three-wire set, another three-wire set analogous to the first one, a third three-wire set analogous to the others, the common winding of the three three-wire sets being juxtaposed and twisted in helical form around a common geometric axis in such manner that the traces of the axes of the three three-wire sets upon a plane perpendicular to the common twisting axis occupy the three vertices of an equilateral triangle, three transformers at each end of each three-wire set, two independent sources of current, a transformer connected to the.

two poles of the first independent source of current, the primaries of the three first transformers being connected respectively with the wires of the three-wire set and disposed on the star system about a central point connected to a special wire, the secondaries of the three first transformers being disposed on the star system about an in sulated point, said secondaries being connected respectively with the ends and the middle point of the secondary of the fourth transformer and the series intercalationof the secondary of the second independent source upon the connecting wire ending at the middle point of the transformer which is connected to the two terminals of the first independent source of current, the application to the three special wires provided each in a three-Wire set of a terminal arrangement similar to those applied to each three-wire set. v

2. A system of electrical communication such as a long distance telephone system comprising the following instrumentalitles:

three conducting units or sets of three wires each twisted in a helical form around a common geometric axis, sothat the centers of the three conductors in each set in anyplane perpendicular to the common axis are at the vertices of an equi-lateral triangle, all of the three unit sets being likewise twisted around a common geometric axis so that in any planes perpendicular to said axis the geometric centers of the three several units will also form an equi-lateral triangle; three transformers at each end of each three-wire set or unit, and two independent vsignaling circuits; one terminal .of the primary of each of said transformers being connected to one of the wires of the three-wireset or unit, and the other terminals of said primaries being connected together and to a special neutral conductor; the secondaries of said three transformers being connected ina star connection without any neutral conductor; a fourth and a fifth transformer, the primaries thereof being connected to said independent transformer having one terminal connected to the central point of the secondary of the fourth transformer and its other terminal connected to the secondary of the remaining one of the first three transformers; the three neutralwires from the three unit sets being conducted to a fourth transformer set arranged in the same manner in every particularas the transformer sets for the individual units, and also connected with two independent signaling circuits; nine individual wire conductors function first in groups of three; each group ofthree serving two circuits; and then the three groups of three function by means of their neutral wires as units forming an additional triplet set, and serve two additional signaling circuits.

In testimony whereof I have signed this specification;

cAMrLLE LOUIS Mann: RAVU'I.

whereby

Images