US2967256A - Protective device - Google Patents

Description

Jan. 3., 1961 F. x. REES PROTECTIVE DEVICE Filed Jan. 9, 1959 INVENTOR. F. X .R EES 7 HIS ATTORNEY United States Patent F PROTECTIVE DEVICE Frank X. Rees, Chili, N.Y., assignor to General Railway Signal Company, Rochester, NJK.

Filed Jan. 9, 1959, Ser. No. 785,818

7 Claims. (Cl. 313-188) This invention relates to insulation-connected conductors, and it more particularly pertains to the provision of a protective device wherewith an approximate ly equal, low-voltage potential is maintained between such insulation-connected conductors.

In railroads, track sections are interconnected at their joints by means of insulation. Connected to these track sections at various locations are many types of electrical apparatus which are operated by a low-voltage range ot specified potentials. These electrical apparatus are manufactured to withstand a potential some limited percent above. their particular, individual operating potentials. Potentials exceeding these withstand-ability values usual'y prove detrimental to the electrical apparatus concerned. Such potentials may arise from lightning intluences, magnetic induction from nearby power lines, and the like. Since such potentials usua'ly arise sporadically and since most ot the electrical apparatus is connected to the track sections constantly, it is desirable to provide a device .which will arrest any abnormal potential arising on any one of the track sections so that protection may be afforded to the associated electrical apparatus. It is also desirable to maintain adjacent track sections at approximately equal, low-voltage potentials since certain types of e`ectrical apparatus are inter-connected between track sections.

Various types of lightning arrestors or other protective devices are currently available with which varied degrees of protection are afforded to electrical appara-- tus in use. Such lightning arrester-s or protective devices are, however, primarily concerned with arresting abnormal potentials individual to their assoclated track sections. From this, it may be ascertained that the potential differences individual to adjacent track sections may be at distinctive and variable values.

In view of the above, one object of the present invention is the provision of a protective device which, when connected between two insulation-connected rails and two opposite, paralel, insulation-connected rails, will maintain each of the four rails at an approximately equal, low-voltage value of potential.

Another object of the present invention is the provision of a protective device constructed with such principles and with such mutually compatible materials that the usefulness and longevity of the protective device is appreciably extended while maintenance is unnecessary.

Another object of the present invention is the provision of a protective device employing an inert gas at such a desirable pressure such as to allow an abnormal potential, with respect to the pressure of the gas, applied to the protective device to be arrested and discharged to ground thereby maintaining an equal, low-voltage potential between the various electrodes and ground.

Another object of the present invention is to enable provision of protective devices for extended interconnected track sections which, when individually connected to adjacent rail sections and their paralel counterparts, will be effective to provide approximately equal, low- 2,967,256 Patented Jan. 3, 1961 ice 2 voltage potentials on each track section of the elongated unit.

Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawings, and in part pointed out as the description of the invention progresses.

In describing the invention in detail, reference will be made to the accompanying drawings, in which like reference charactres designate corresponding parts throughout the several views, and in which:

Fig. 1 illustrates a top view of the instant invention mounted on hoding clips which are further mounted to an insulation board connected to a mounting rack;

Fig. 2 shows a partial side View taken on the lines 2-2 of Fig. l which further shows the details of construction ofthe instant invention; and

Fig. 3 is a diagrammatical view illustrating the use of the instant invention with an ordinary direct current track circuit which includes a track relay and its associated resistance, and a battery with its associated resistance.

In general, with reference to Figs. 1 and 2, a protective device PD as shown consists of a cylindrical, transparent body 1 having four cylindrical, transparent arms protruded outwardly from the sides in a spaced relationship and a cylindrical, transparent arm 9 protruded out- Wardy from the top of the body 1. The ends of the arms 3 and the arm 9 are open. Fused to the circular edges of the arms 8 and the arm 9 are metallic discs 3. Butted against the outside surface of each metallic disc 3 is a metal electrode 4. Butted against the inside of each metallic disc 3 directly opposite electrode 4 is another metal electrode 5. Attached to the free end of each metal electrode 5 associated with each of the arms 8 is la spherically-shaped carbon anode 6. Attached to the free end of the metal electrode 5 associated with arm 9 is a. cylindrically-shaped ground electrode 7. The arms 5 are of suitable lengths so as to locate the anodes 6 and the ground electrode 7 in the same plane.

More specifically, the transparent body 1 has the cylindrical arms 8 protruding outwardly from its side spaced at intervals. As may be seen in Fig. 2, the body 1 and the arms 8 are formed so as to have the portions of the body 1 directly above and below each arm 3 of equal area. While the bottom of the body 1 is a flat surface, an arm 9 protrudes from the top surface. This arrn 9 is axially located with respect to the body 1. The free end of each arm is provided entirely open for the ensuing purposes. To provide the transparency and durability required of the body 1 and its associated arms, a suitable type of glass, plastic or the like is used.

Fused to the circular end of each of the arms 8 and the arm 9 are metallic discs 3. Each of the discs 3 is preferably formed of a metal compound which contains iron, nickel, and cobalt. The symbolic designation for this compound is commonly given as FeNiCo and for convenience, this compound will be referred to hereinafter by its symbolic equivalent. FeNiCo was selected for use in this instance because of its coeflicient of expansion, i.e., it has the same coeicient of expansion as does the glass material specifically used in forming the body 1, the arms 8 and the arm 9. This selection is made to insure a compatible relationship between the glass and FeNiCo. That is, should the coeicient of expansion be different, the glass could very possibly crack or break when heated repeatedly. This is very common in glass bulbs or tubes sold commercially, i.e., many of these bulbs or tubes provide leadin wires and glass having dilerent coeicients of expansion. When heated re* peatedly, the glass has a tendency to crack or break as is experienced where the pinched glass method is utilized.

The protective device PD constructed as above described is exhausted to yield a partial vacuum within the glass enclosure of such a value that abnormal potentials may be discharged from the conductor with minimum delay an-d resistance. The extent of the partal vacuum to which the device is exhausted may be'obtained by a choice ofsuitable pumps, such as are commonly used in the art. To enhance the effectiveness of the protective device PD, it is desirable to include an atmosphere of a monatomic gas such as argon, neon, helium, or the like. The variable pressures which the different gases may assume permits wide-spread use of a standardized prote-tive device such as is presented herein. When the above is accomplished, the glass enclosure may be hermetically sealed in any suitable fashion.

A metal conductor electrode 4 is butted against the outside of each metallic disc 3. These electrodes 4 may be suitably secured to the disc 3 by soldering, Welding, or the like. On the inside surface of each disc 3 directly opposite each electrode 4 is butted another metal conductor electrode 5. These electrodes 5 may be secured in the manner as stated above. The electrodes 4 butted to the outside surface of the disc 3 associated with arms 8 are provided for mounting purposes and for connecting the protective devices PD in a desired circuit while the electrode associated with arm 9 is for providing a ground connection.

Attached to each of the four electrodes 5 associated with the arms 8 on their free ends is a carbon anode 6. This anode 6 is preferably spherical-shaped except where it is connected to its respective electrode 5. A cut-out portion 16 is provided in anode 6 so as to receive the end of its respective electrode 5. Carbon is suggested as being used for the anode material because of its conducting characteristics, but it should be understood that material with similar conducting characteristics may be used.

A cylindrical ground electrode 7 is attached to its electrode 5 which is associated with arm 9. This is accomplished by by inserting electrode 5 into a cut-out portion provided in the ground electrode 7. The electrode 5 is allotted a length such as to provide the anodes Gand the electrode 7 in the same plane. This structure is effective in realizing a more etiicient dissipation of abnormal potentials existing between any one of the anodes 6 and the ground electrode 7.

The protective device PD may be mounted on an insulation block 12, as is shown in Fig. 2. Connection is provided to any desired circuit through mounting clips 13. The metal electrodes 4 associated with arms 8 are inserted into these clips 13, as shown. The block 12 may be secured to a mounting rack 19 by bolts 18 and their respective nuts 17. A ground connection is made directly to the electrode 4 associated with arm 9.

To further clarify the extent of protection that the instant protective device PD would normally encompass singly and in multiple, a typical track circuit is diagrammatically shown in Fig. 3. Here, two protective devices PD are shown to be connected respectively to four of six rails 30, 31, 32, 33, 34 and 35. Insulation 25 is provided to insulate the rails at their respeciive joints 22, 23, 28 and 29 located at stations l and 2.

As in a normal track circuit, a track battery B and a limiting resistance R1 are connected in series fashion from rail 31 to rail 33 and correspondingly from rail 34 and 35. Between the rails 30 and 32 separated respectively from rails 31 and 33 by insulation material 25 at station 1, a track relay TR and a relay series resistance R2 are connected in series fashion. Likewise, a relay TR and a relay series resistance R2 are connected in series fashion between rails 33 and 31 separated respectively from rails 34 and 35 at station 2. The relay TR may be used for a variety of purposes, such as control of signal mechanism and the like. It is well known that a track relay TR can withstand voltages up to approximately 2500 volts. Protection must be alorded for greater voltages to insure against destruction and/or damage to the relay-TR andits associated circuitry. This sort of protection may well be rendered by the instant invention. For example, as sume that a voltage of substantial magniture, i.e., approximately 3000 volts, is induced onto rail 32 by an extraneous source. This couldv very well be detrimental to relay TR associated with rails 30V and 32 as noted above. Assuming the pressure, andbdistribution of the gas in the device PD is in accord with the various aspects to be taken into consideration such as the distance between the separate anodes 6 and the ground electrode 7, the breakdown voltage desired, and the like, the gas between anode 6 and the ground electrode 7 will immediately become ionized due to the potential difference, thus allowing the abnormal voltage to be discharged to ground. Ionization of the gas or dielectric used permits smaller potential differences than 3000 volts which may exist between rails 30, 31 or 33 and the ground electrode 7 to be discharged at the same time, thereby maintaining equal voltages between the anodes 6 and the ground electrode 7. This is based on the assumption that each of these smaller voltages is of insufficient value in itself to ionize the gas molecules, or in any way cause a breakdown of the gap between each anode 6 and the ground electrode 7 of the protective device.

To better comprehend how two such protective devices might co-act to provide an equal low-voltage potential on their associated rails, let it be assumed that the 3000 volts was induced onto rail 33 between stations 1 and 2. In this instance, the gas or dielectric within the two protective devices shown would ionize or otherwise breakdown which further would result in a discharge of voltage to ground through the ground electrode 7. It is impera-- tive, in this case, that the pressures of the gas or other dielectrics within the two protectivedevices be as equal as is feasible. This would allow the two protective-devices to be equally effective against any such extraneous abnormal voltages.

It should be noted here that the ground as shown in Fig. 3 should be common to all electrical apparatus which may be connected to any one or all of the six rai-153i?, 31, 32, 33, 34 and 35. This is of utmost importance since it is well known that various and different grounds are not necessarily at the same values of potential, i.e., when a discharge of abnormal voltages is being effected, various grounds may have potential diierences as much as several thousand volts. In view of this, it is desirable to have a common ground for any one particular elongated length of track sections. Such a ground may be conveniently provided by an extensive water system.

In some instances, however, such as with coded track circuits, it may be desirable to eliminate the ground electrode 7 and its associated metal electrodes 4 and 5. In these cases, the electrical conductors or rails are of suficient length and the like to dissipate the energy resulting from an extraneous potential inducement or the like onto a particular rail associated with a device PD, thus negating the need of a ground connection. The device PD will then maintain the potential value on its associated four rails in accordance with the pressure and type of gas used as well as the spacing of the anodes 6.

Having described a protective device, as one specic embodiment of the present invention, it is desired to be understood that this form is selected to facilitate in the disclosure of the invention rather than to limit the number of forms which it may assume; and, it is to be further understood that various modifications, adaptations `and alterations may be applied to the specific form lshown to meet the requirements, without in any manner departing from the spirit or scope of the present invention.

What I claim isz.

1. A protective device comprising, in combination, a centralv body, a plurality of longitudinal electrodes intersecting said body and supported thereat, each of said electro-desA within said body having -a carbon tip electrically connected thereto, one of said electrodes being connected to ground, the other of said electrodes being radially disposed and substantially equally spaced about said one electrode and normal to said one electrode, the carbon tips of said other electrodes being substantially equally spaced about the carbon tip of said one electrode and in the same plane as the carbon tip of said one electrode.

2. A protective device as specified in claim 1 wherein each of the carbon tips for the other of said electrodes are spherically shaped and the carbon tip for said one electrode is cylindrically shaped to provide a spark gap which increases in width in the direction of movement of the arc thereby causing the arc to be extinguished.

3. A protective device as specified in claim 2 wherein said body has a plurality of arms extending outwardly in one plane each for receiving one of said other electrodes and an arm extending outwardly in another plane for receiving said one electrode.

4. A protective device as specified in claim 3 wherein each of said plurality of arms has a shaped conductor having substantially the same coeicient of expansion as the body material fused to its end furtherest from said central body.

5. A protective device as speciedin claim 4 wherein each of said longitudinal electrodes comprises two longitudinal electrodes with one such electrode fused to each side of the shaped conductor for a respective arm along the same axis.

6. In combination, an electrical circuit, a plurality of quickly detachable mounting clips, a protective device having a hollow central body formed of nonconducting material, a plurality of longitudinal electrodes intersecting said central body in a predetermined manner and supported thereat, and a plurality of carbon tips each connected to one 0f said longitudinal electrodes within said body and spaced so as to form spark gaps therebetween, said clips being adapted in combination to physically support and electrically include said protective device in said electrical circuit to permit abnormal voltage surges occurring in such electrical circuit to be discharged by said protective device.

7. A combination of elements as specified in claim 6 wherein each of said longitudinal electrodes outside of said body has a cylindrical shape so as to be readily adapted to one of said plurality of quickly detachable mounting clips for arranging said other electrodes in said clips in one plane for facilitating in the connection to said electrical circuit.

References Cited in the file of this patent UNITED STATES PATENTS 1,181,576 Day May 2, 1916 2,116,702 Kern et al May l0, 1938 2,830,216 Laurin Apr. 8, 1958 2,854,567 Staples et al Sept. 30, 1958 2,875,366 Bauman et al. Feb. 24, 1959

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