US1750233A - Railway signaling track-circuit regulator - Google Patents

Description

March 11, 1930. s. M. LUCAS 1,750,233

RAILWAY SIGNALING TRACK CIRCUIT REGULATOR Filed Nov. 22, 1927 INVENTAOR 1 5 M A u 0a s,

Patented Mar. 11, 1930 UNITED STATES PATENT: OFFICE SAMUEL M. LUCAS, or PITTSBURGH, PENNSYLVANIA, ASSIGNOR To THE UNION SWITCH & SIGNAL COMPANY, or SWISSVALE, PENNSYLVANIA, A CORPORATION or PENNSYLVANIA RAILWAY SIGNALING TRACK-CIRCUIT REGULATOR Application filed November 22, 1927. Serial No. 234,935.

My invention relates to railway signaling track circuit regulators, and has for an ob- .ject the provision of novel and improved means for preventing excessive energization of the track relay when the track ballast is dry, and, consequently, has relatively high resistance.

I will describe several forms of track circuit regulators embodying my invention, and will then point out the novel features thereof in claims. a

In the accompanying drawing, Fig. 1 is a diagrammatic View showing a track circuit having applied thereto one form of regulator embodying my invention. igs. 2 and 3 are views showing modifications of the regulator shown in Fig. 1 and also embodying my invention.

Similar reference characters refer to similar parts in each of the several views.

Referringfirst to Fig. 1, the reference char- 4 insulated joints 2 to form a track section. I

This section is provided with a track circuit comprising the rails of the section, a source f I -in which equation E is the applied potential, e is the over-voltage, and 1" is the internal resistance of the cell. Considering this equation, it is obvious that when E is a variable of current connected across-the rails at one point, and a track relay R having a winding connected across the railsat another point. As here shown, the source of track circuit current is atransformer T having its secondary connected across the rails 1 and 1 and having its primary connected with a source of alternating current which is not shown in the drawing. A limiting impedance 3 is interposed between the secondary of transformer T and one of the track rails in accordance with usual practice.

In a track circuit of the type just described, it is necessary to so adjust the source of current that it will maintain the normal operating voltage across the relay winding during the lowest value of ballast resistance, that is, during the time of maximum saturation of the ballast with water. When the ballast resistance rises, however, the voltage provided to prevent an increase of current in the relay due to increase of voltage across the track rails at the point at which the relay is connected with the rails.

In accordance with my invention, I provide a regulator connected across the rails adjacent the relay and so adjusted as to conduct current when and only when the voltage across the relay winding rises a given amount above the normal operating value. As shown in Fig. 1, this regulator is an electrolytic cell of such nature that a gas is evolved when current flows through the cell, and current will not flow through the cell until the potential between the electrodes exceeds a definite value known'as over-voltage. Vhen the applied potential exceeds the over-voltage, the current which flows through the cell is limited only by the internal resistance of the cell, that is,

, m E e between zero and maximum, no current will flowthrough the cell until E exceeds 6, but

when E does exceed e, if r is small, the current through the cell will increase very rapidly with increase of'E. The combination of electrodes and electrolyte is so chosen that e, the over-voltage of the cell, is slightly higher than the normal operating voltage of I the relay R. It follows that when the ballast resistance is low, no current will flow-- through the cell C, and the relay R will then receive all of the energy transmitted to the relay end of the track section. When the bal- ,.last resistance rises, however, current will .flow through the cell G as soon as the potential across the relay exceeds the over-voltage of the'cell. By suitably proportioning the .cell to they track circuit characteristics, the consequent in urlous eflects unless means are cell can be made to preventany decided increase in thecurrent through the. relay, andso to prevent injurious eflects on the relay due to over-energization.

It may not always be possible to secure the most economical operation of the relay when the relay is designed for an operating voltage which would match with the overvoltage of a given electrolytic cell. In such cases a transformer may be interposed between the cell and the track rails, as shown in Fig. 2. Referring to this view, the transformer A has its primary connected across the track rails and its secondary connected with the electrodes l and 5 of the cell C. The transformer A has such ratio that the over-voltage of the cell 0 is substantially equal to the normal operating voltage of the relay R multiplied by the ratio of the transformer. v

Referring now to Fig. 3, the regiilatingdevice in the form here shown, comprises two electrolytic cells C and C each having a tantalum electrode and a lead electrode immersed in a solution of sulphuric acid 6. A cell of this character has a much higher resistance in one direction than in the other direction, and, consequently, it is necessary to oppositely connect two cells in multiple when the source of current for the track circuit is alternating.

Although I have herein shown and described only a few forms of track circuit embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention. Y

Having thus described my invention, what I claim is:

1. In a railway signaling track circuit of the type comprising track rails, a source of current connected across said rails, and a track relay having a winding connected across said rails,the combination with the aforementioned instrumentalities 'of an electrolytic cell connected across said rails and adjusted to conduct current when and only when the voltage across said relay winding is above a given value. 1

2. In a rallway signaling track clrcuit'of the type comprising track rails, a track relay having a winding connected across said rails, and a source of current also connected across said rails and adjusted to maintain the normal operating voltage across said relay winding during the lowest value of ballast resistance, the combination with the aforementioned instrum'entalities of an electrolytic cell connected across said rails and adjusted to conduct current when and only when the voltage across said relay winding rises a given amount above the normal operating value. p

3. In a railway signaling track circuit of the type comprising track rails, a track relay having a winding connected across said rails,

and a source of current also connected across said rails and adjusted to maintain the normal operating voltage across said relay Winding during the lowest value of ballast resistance ,the combination with the aforementioned instrumentalities of a device connected across said rails and having the characteristic of conducting current when and only when the voltage across said relay winding rises above the normal operating value.

4. In a railway signaling track circuit of the type comprising track rails, a track relay having a winding connected across said rails, and a source of current also connected across said rails and adjusted to maintain the normal operating voltage across said relay Winding during the lowest value of ballast resistance, the combination with the aforementioned instrumentalities of an electrolytic cell connected across said rails and having an electrolyte and electrodes characterized by the fact that gas is evolved when Cltllht flows through the cell, said cell being adjusted to conduct current when and only when the voltage across said relay winding rises a given amount above the normal opcrating value.

5; In a railway signaling track circuit of the type comprising track rails, a track relay having a winding connected across said rails, and a source of current also connected across said rails and adjusted to maintain the normal operating voltage across said relay winding during the lowest value of ballast resistance, the combination with the aforementioned instrumentalities of a transformer having its primary connected across said rails, and an electrolytic cell connected with the secondary of said transformer, said cell being adjusted 'to conduct current when and only when the voltage across the cell rises above the normal operating voltage across said relay winding multiplied by the ratio of said transformer.

In testimony whereof l' fiix my signature.

' SAMUEL M. LUCAS.

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