US1295886A - Distributing system for electric railways. - Google Patents

Description

C. LE G. FOR LESCUE.

DISTRIBUTING SYSTEM FOR ELECTRIC RAILWAYS.

AFPUCA'HON FILED JUNE 5. ma.

1,295,886. Patented Mar. 4,1919.

2 SHEETS SHEET I.

WITNESSES: 32 INVENTOR /0 BY a ATTORNEY C. LE G. FORIESCUE.

blSTRIBUTING SYSTEM FOR ELECTRIC RAILWAYS.

APIUCATION nuao JUNE s. 1916.

2 SHEETS-SHEEI 2.

6 l 2 6 6 g is? 71' Q I 25" I WITNESSES 6 7 INVENT R 4 5 [bar/es Zefifirfescue UNITED STATES PATENT OFFICE.

CHAR-LES Li? G. FORTESCUE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC AND VANIA.

MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- I JIS'I'RIBUTING SYSTEM FOR ELECTRIC RAILWAYS.

Specification of Letters Patent.

Patented Mar. 1, 1919.

Application filed June 5, 1818. Serial No. 101,732.

To all whom it may concern:

Be it known that I, CHARLES LE G. Fon'ms- CUE, a subject of the King of Great Britain,

and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Distributin Systems for Electric Railways, of which t e following is a specification. My'invcntion relates to electrical distributing systems and particularly to electric railway systems that employ alternating currents for propulsion purposes. i More particularly, my invention relates to electric railway systems of the above indi: cated character which embody means for minimizing inductive disturbances that arise from the flow of propulsion currents and are impressed upon adjacent circuits, such as intelligence-transmission circuits, thereby interfering with their satisfactory operation.

Many systems have heretofore been proposed for minimizing the inductive disturb ances impressed upon one electrical circuit by another adjacent circuit but complete neutralization of the inductive efiects has not been obtained in all cases. A particular system used in connection with electric railways which has given fairly good results embodies the use of series transformers to inductively interlink the trolley conductor and the track circuit, whereby the return flow of the trolley currents may be confined to the track rails or to portions of the earth closely adjacent to the track rails. In this manner, the zones of disturbing induc-in influences arising from the return flow 0 the power currents are restricted and such currents are confined to limited regions close to the trolley conductor where their inductive efi'ects on an adjacent intelligence-transmission circuit minimize or neutralize, to some extent,

No. 66,733, filed December 14, 1915, and assigned to the Westinghouse Electric & Mfg. Company. This proposed railway system comprises a feeder conductor, a trolle conductor and a track circuit, the two ormer conductors being so positioned with respect to an adjacent intelllgenoe-transmission circuit, which is to be protected against inducti ve disturbances arising therefrom, that the resultant electromot-ive forces induced therein by reason of the current flowing in the trolley and feeder circuits shall be neutralized. to such a. degree as willnot seriousl interfere with the operation of the intelllgence-transmission circuit. Moreover, the trolley and feeder conductors are indnctivel interlinked, either with or without the traci: circuit, through transformers of a character similar to those employed in connection with the system disclosed in the above-mentioned ap lication of;Charles F. Scott.

object of iny' present invention is to provide an improvement in the systems disclosed in the aforementioned a plications and particularly in that covered i y a plica-' tion, Serial N 0. 66,733 in which distur ances arising from the flow of alternating currents III the distributing system and tending to interfere with the satisfactory operation of other circuits adjacent thereto, such as intelligence-transmission circuits, may be substantially neutralized in order to insure the satisfactory transmission of intelligence over the circuits subject to such disturbances.

To understand more fully the scope of my present invention, reference may be had to the following description and the accompanying drawings in which Figure 1 is a diagrammatic view of a railway system embodying a form of my invention; Fig. 2 is a simplified arrangement illustrating the system of Fig. 1;. Fig. 3 is a diagrammatic view showing a substitute arrangement for the transformersemployed in the systems of Figs. 1 and 2; Figs. 4, 5 and 6 are diagrammatic views of the character of Fig. 2 showing modified forms of the system of Fig. 1..

Referring to Figs. 1 and 2, a trolley conductor 1 supplies power to a railway svstem comprising a trac into a plurality of insulated sections 3 (one only of which is shown) employed for signahng purposes, This is a usual way of dividing the track circuit into a series of block sections each one of which may be procircuit 2 that is dividedtoo v the trolle tected by its own locally-controlled signal- A return feeder 4, aralleling conductor 1, provi es means whereby t e propulsion currents may return to the source of power supply of the system which, in this instance, is represented as a single pbase alternator 5. One terminal of the alternator 5-is connected to the trolley conductor 1 and the other terminal -is con nected to the return feeder 4, the full potential of the alternator 5 bein impressed across the aforementioned con uetors. At spaced intervals in the, trolley conductorl, are insulating joints 6, similar joints 6 being correspondingly positioned in the return feeder 4. For convenienc'e, the insulating joints 6 and 6 may be placed at points coring device.

responding to the position of insulating joints 7 in the track circuit 2, the latter be-' ing provided in order that sections of the track circuit may be'employed as local circuits or blocks for the electric si alin system. Associated with pairs 0 insu ating joints 6 and 6 are transformers 8 and 8, the primary windings 9 and 9 thereof being connected in series-circuit relationship with the trolley conductor 1 and in shunt to the insulating joints 6, and secondary windin 10 and 10 being connected in series-circuit relationship with the feeder conductor 4 and in shunt to the insulating joints 6. Two transformers 11 and 12 are associated with each division of the trolley and feeder conductors '1 and 4, one of said transformers having windings 13 and 14', and the other havingwindi 15 and 16. The windings13 and 14 an the windings 15 and 16 are interconnected with *each other at common points 16" and 16", respectively, which points, in turn, are connected, through a conductor 17, to mid-points 18 on im edance bonds 19 that are inserted on I th sides of the t ack-insulating oints 7. -The impedance bonds 19 are of t e usualform of construction, such as are employed in electric railway s stems e uipped with electrical signaling evices 0 any usual form. When the signalin system comprises a plurality of insula block sections, correspondingterminals of thev windings 13 and 15 of the transformers 11 and'12, respectively, are connected by means of conductors 20and 21 to the terminals ofthe primary windin 9 of the series transformerfi, as shown in the drawing. The other terminals of the windings 13 and 15.areconuected to the windings 14 and 16, respectively, the free terminals of these latter windings being connected, by means of conductors 22 and 23,

to the terminals of the secondary winding 10 of the series transformer 8. A condensive reactance element 24 of proper value is connected directly across the terminals of the winding 9 and, similarly, a second condensive element 25 is connected across the terwindings of the separate transformers.

related, as mentioned-above.

minals of the secondary winding 10 of the series transformer 8.

An intelligence-transmission circuit 26, shown as a telephone circuit, is disposed in. proximity to the trolle conductor 1 and the eeder 4, and is,there ore, subject to the inductive effects arising from the flow of propulsion currents in the railway system. For

the satisfactory operation of the telephone circuit 26, it is essential that the inductive disturbances impressed thereupon be mini fore, by proplerly proportioning the currents" flowing m t e several directions in thedistributing circuit, and b suitably placing the circuit conductors wit respect to the telephone circuit, the electromotive forces induced in the tele honecircuit will be substantially neutra lzed by inducing therein equal and oppositely-directed electromotive forces under all conditions of load distribution on the railway system.

' In Fig. 2, I have shown a simplified form of the system in Fig. 1 in which the transformer windings are more suitably arranged to facilitate in explaining their inter-relations. to be uniformly and equally spaced from the trolley conductor 1 and the return feeder 4. The track circuit 2, in this instance, is held at a potential midway between the potential of the trolley conductor 1 and that of the feeder conductor 4 by means of the transformers 11 and 12, since the track circuit 2 .is connected to the points 16" and 16 which re resent common mid-points between Xhe ccordingly, the ratio of the windings of each of the transformers 11 and 12 is unity, the secondary windings 13 and 15 having induced therein electromotive forces equal to those impressed u on the windings 14' and 16, since the win ings 15 and 16 and the windings 13 and 14 are mutually inductively Furthermore, the windings 9 and 10 of the series transformers 8 are mutually inductively related and, in this instance, comprise equal numbers of turns. The condensers 24 and 25 are selected to have suitable capacities for supplying the magnetizi currents of the transformers 8 and 8". n other words, the im pedance oil'ered by the windings 9 and 10 of the series transformers 8 and 8 to the'flow The telephone circuit 26 is assumed all of the propulsion currents in the railway system is annulled or rendered negligible. This condition is maintained for currents having the frequency only of the propulsion 5 currents. The signaling currents,,for which the insulated track section 3 constitutes a local circuit, are afforded a very high impedance by the combination of the condensers 24:, and their associated inductive windings 9 and 10, and are, therefore, substantially precluded from flowing between adjacent traclc or block sections which is a very desirable condition since it lessens the danger of signaling devices indicating wrong trailic conditions.

To further illustrate the electrical conditions obtaining in the railway systempf Fig. 2 at a certain instant, assume that a' locomotive 26' occupies the mid-position on the track section 3. The propulsion currents, which traverse the trolley and feeder circuit and which are represented b the full-line arrows 27, flow through the winding 9 015 the transformer 8, along the trolley conductor 1 and a trolley pole 28 to the locomotive 26. int, the propulsion currents divide that flow along the At this equally in two portions track circuit 2 in-opposite directions, since it is presumed that t e track circuit 2 constitutes a uniform conductor and the train 26 occupies a mid-position thereupon, as mentioned above. One-half of the ropulsion current flows through the impedance bonds 19, the conductor 17, the winding 16 of the transformer 12, the conductor 23 and the secondary winding 10 of the transformer 8 to the return feeder 4. The other half of the propulsion current flows along the track circuit 2, the impedance bonds 19" the conductor '17", the winding 14" of the transformer 11 to the return feeder 4. It will be apparent,,therefore, that the propulsion currents flowing in the trolley conductor 1 intermediatethe generator 5 and the point A of the stem is equal in value to, and opposite in direction from, that of the propulsion ctfirrent flowing in the corresponding portion a o .the

ductive fefi'ects arising from the fiowof the propulsion currents over this portion of the railway system are neutralized. T.

, 'It becomes necessary, therefore, to ne'utralize the inductive effects arising from the flow of the propulsion currents in the por- 5 tion of the railway system extending between the two groups of-transformers. As mentioned above, one-half of the propulsion current flows through the winding 16 0f the transformer 12. An equal and o winding 15 of the transformer 12, which induced current is represented, in direction, by the broken-line arrows 29. A local closed circuit, is consequently, established over i which an induced current, equal to onereturn feeder 4. Therefore, 'the in ptpositely directed current is therefore induce in the half of the propulsion current, flows, and this local circuit comprises the winding 15 of the transformer 12, a section of the trolley conductor 1, the trolley pole 28, the train 26, a portion of the track circuit 2 and the impedance bond 19. Similarly, one-half of the pro ulsion current flows also throu h the winding 14" of the transformer 11". m consequence thereof, current which is represented by the dot-and-dash arrows 30 and is equal in value to the second portion of the propulsion current but flowing in an o posite direction thereto,'is induced in a coal closed circuit which comprises thewinding 13" of the transformer 11", the conductor 20", a section of the trolley conductor 1, the trolley pole 28, the train 26, a section of the rail circuit 2, the im edance bond 19* and the conductor 17". ince the induced current flowing through the windirgltr" is equal and opposite to the induced current flowing in the winding 15, the said currents, simultaneously traversing the trolley conductor 1, neutralize their separate inductive Teffects impressed upon the telephone conductor 26. Again, the inductive effects arising from the propulsion current flowing along the trolley conductor 1 to the trolley pole 28 are neutralized by the inductive effects arising from the flow of the ortion of the propulsion current flowing a ong the section of the return feeder ,that is intermediate the two groups of transformers. Since, as previously assumed, the train 26" occupies a illll dposition on the track section 3, the corre sponding section of the trolley conductor 1, over which the entire propulsion current flows, subtends a length of the telephone circuit 26 that is equal to one-half the length thereof subtended by the aforementioned portion of the return feeder 4 intermediate the two transformer groups, over which pore tion of the return feeder one-half of the pro- The propulsion curpulsion current flows. rents, in all instances, pedance when flowing throu h the series transformers 8 and 8 since t e condensers 24 and 25 are so selected or tuned with the inductive reactance of the windingsof the transformers as to annul the impedance of are offered zero imthe windings 9 and 10 with which they-are associated. As a result of the aforementioned distribution of the prop lsion' cur-" rents, the inductive disturbances, impressed upon the telephone circuit 26 are substantially neutralized under all load obtaining in the railway system.

In Fig. 3, the transformer 8 is shown as comprising a third winding 81 which is in- 'ductively related to both windings 9 and 10. A condensive-reactance element 32 is connected in closed circuit with the winding 31 and, in this manner, means'are provided for annulling the inductive characteristics of the windings 9 and 10 resulting from the flow of conditions Ill the magnetizin currents therein. The structure shown in ig. 3 is substantially an electrical e uivalent of the transformer 8 of Fig. 1 in which the condensers 24 and 25 are respectively connected in shunt to the windin 9 and 10.

efcrring to Fig. 4, the windings 9 and 10 of the'series transformers 8 are connected across the insulating. joints 6 and 6 in the trolley conductor 1 and the return feeder 4, respective] through resonating transformers 33. ach resonatin transformer 33' comprises a. primary winding 34-and a secondary winding 35, the latter being connect ed in closed circuit with a condensive element 36. By the use of such an arrangement, 9. much smaller condensive element may be employed and the combined effect of the reactive element and such condensive element is that of a comparatively large condenser. The condensive reactance of such a resonating transformer is so selected that it compensates for the inductive reactance of the transformer windings 15, 16, etc., when alternating currents having the fre uency of the propulsion currents traverse t e several circuits described in detail in connection with the system of Fi 2. In other words, the local circuits estab ished by the transformer windings 15 and 16 and the locomotive 26'-constitute mr'ies resonant circuits for alternating currents having the frequency of the propulsion currents. This condition is maintained irrespective of the position of the locomotive 26 on. the track. The division of the propulsion currents between the several local circuits is. conseuently dependent only upon the ohmic resistance of the separate circuits, which resistance varies in value as the locomotive traverses the system. This insures a correct division of the propulsion current, under all conditions of operation inthe railwa sections occupied by the locomotive an consequently, the inductive disturbances that may be impressed u on the telephone conductor 26 will be su stantially neutralized, since the induced currents in the telephone circuit will, under all conditions, have proper phase relationships. Of course, in selecting the condensers 36, the electrical characteristics of the locomotive 26" must be ascertained in order to insure that the local circuits formed bythe locomotive 26 will constitute series resonant circuits of suitable character.

In Fig. 5, the condensers 36 of Fig. 4 are connected intermediate the power transformer windings 15 and 16 and the windin 9 and 10 of the series transformer 8.. ff: this position, the condensers 36 are subject to the currents flowing through the transformer windings-15 and16 only. The condensers 36, however, are so chosen that the local circuits established by the locomotive 'derstood by 26 will, in all instances, constitute series resonant circuits, as mentioned above.

In Fi 6, the condensers 36 are connected intermedi and 16 and the impedance bonds 19. In this position, they act under all conditions as the condensers 36 of Fig. 5, the object also being, in this case, to provide series resonant circuits.

Of course, it will be understood that the ratios between the transformer windings of the transformers 11 and 12 of Figs. 1 and 2 need not necessarily be unity. as has been assumed in the foregoing description. The potential of the track circuit, 2 may be other than the mid-potential between the .trolley conductor 1 and the return conductor 4. In this instance, however, the spacing in the trolle conductor 1 and the return feeder 4, with respect to the telephone conductor 26, should be so adjusted and proportioned that the inductive efi'ects impressed thereupon by reason of the flow of the propulsion currents may be substantially neutrahzed. It will be presumed, however, that the currents flowing in the several 10- cal circuits will, in all cases, be substantially inversely proportional to the impedances 'of several circuits which, when properly tuned to the frequency of the propulsion currents, constitute circuits having ohmic resistance only.

hile I have shown and described several embodiments of my invention, it will be unthose skilled in the art that many modifications may' be made therein without departing from the spirit and scope of the appended claims.

I claim as my-inventionz 1. An electric railway system comprising a trolley conductor, a return feeder therefor, a track circuit, a. transformer having its inducing and induced windings connected in series relationshi between the trolley conductor and the eeder, inductively related windings for interlinking the trolley conductor and the feeder with each other, means for connecting an intermediate point of the said transformer windings to the track circuit, and condensive-reactance elements connected in circuit to compensate for the inductive reactance of the windings of said transformer when alternatin currents of a given frequency are impresse upon the system.'

2.'An electric railway system comprising a trolley conductor, a return feeder therefor, a track circuit, means whereby the propulsion currents flowing from the track circuit to the return feeder may induce currents to flow in a local circuit comprising the trolley conductor and the track circuit, and additional means whereby said local circuit may constitute a resonant series path for the flow of alternating currents of a certain predetermined frequency.

ate the transformer windings 15 1,295,888 til ductor with each 01 her, a plurality of trans-' formers having inductivel '-related windin and connected in circuit on each side of said first inductively-related windings, the primary windings of said transformers being interconnected between the track circuit and the return feeder, and the secondary windin 5 thereof being connected to the track circult and the trolley conductor.

4. An electric railway system comprising a-trolley conductor, a return feeder therefor, a track circuit, a plurality of spaced series transformers for inductively interlinking the trolley conductor and the feeder, and a transformer connected in circuit on each side of said series transformers for interconnecting said trolley conductor, said return feeder and said track circuit with one another.

5. An electric railway system comprising a trol cy conductor, a return feeder therefor, a trac circuit, a plurality of spaced series transformers for inductively interlinking the trolley conductor and the feeder with each other, a transformer connected on each side of said series transformers having its primary winding connected between the track circuit and the feeder and its secondar winding connected between the track circuit and the trolley conductor, and condensivereactance elements to compensate for the phase lag of the magnetizing currents supplied to said transformers.

6. An electric railway system comprising a trolley conductor, a return feeder, a track circuit, a plurality of spaced inductively related windings for interlinking the trolley conductor and the feeder with each other, transformers for interconnecting the trolley conductor, the feeder and the track circuit with one another, and condensivc-reactance elements to compensate for the inductive reactance of said transformers, whereby the several circuits comprising said transformers, the trolley conductor, the feeder and the track circuit constitute series resonant circuits for alternating currents having a predetermined frequency.

7. An electric railway system comprising a trolley conductor, a return feeder therefor a track circuit, series transformers inserted at spaced intervals for inductively interlinking the trolley conductor and the feeder with each other, a power transformer connected in circuit with the railway system positioned at each side of said series transformers, and condensive-reactance elements associated with said power transformers, whereby their inductive reactance may be completely compensated for when subjected to the flow of alternating currents having a predetermined frequency.

8. An electric railway system comprising a trolley conductor, a return feeder therefor, a track circuit, insulating joints inserted at corresponding points in the trolley conductor and the fee er, series transformers havin their windings connected across said insu ating joints to inductively interlink the trolley conductor and the feeder with each other, inductively related windings on both sides of said series transformers, said inductively-related windings being connected in series relationshi across the trolley conductor and the fee er and having intermediate points thereof connected to said track circuit, and condensive-reactance elements associated with said inductively related windings to compensate for their inductive rcaotanoe when impressed with alternating cur rents of a predetermined frequency.

In testimony whereof, I have hereunto subscribed my name this 27th day of May, 1916.

CHARLES LE G. FORTESCUE.

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