US2042421A - Electrical installation - Google Patents

Description

Patented May 26, 1936 2,042,421

UNITED STATES PATENT oFFIcE ELECTRICAL INSTALLATION Ralph W. Atkinson, Perth Amboy, and Albert M.

Hagen, Woodbridge, N. 3., assignors to General Cable Corporation, New York, N. Y., a corporation of New Jersey Application December 12, 1934, Serial No. 757,242

8 Claims. (Cl. 138-29) This invention relates to electrical installations 6 and l. Conveniently the cylindrical casing and and equipment, and more particularly to such inthe end members are made of metal and are stallations and equipment which include insula- Welded together at their contacting surfaces. In tion of a liquid character which is to be kept free the illustrative embodiment the connector 4 com- 5 of moisture, air and other gases. It is an object municates with the container through an open- 5 of the invention to provide an improved means ing in the upper end member 8.

for maintaining the integrity of the insulation. Within the container of the illustrative em- Other objects and advantages of the invention bodiment is a cylindrical wall 8 slightly smaller in will appear hereinafter. diameter and of less length than the casing 5.

10 The invention will be best understood from the This cylindrical wall is secured to the container, 10

following description when read in the light of concentrically therewith, with a fluid-tight joint the accompanying drawing illustrating a specific adjacent the lower end of the container, and conembodiment of the invention. In the drawing: venient y y be Welded at its lower end to the Fig. 1 shows in vertical section a reservoir for end member 1. Thus there is provided a thin liquid insulation connected, by way of example, annular Space between the casing 5 d e Wal 15 with a cable joint; and 8 for a portion of the length of the container.

2 shows to enlarged scale the valve for In the drawing this annular space is shown controlling the flow of liquid insulation into and w at exaggerated in t k s mer ly for out of the reservoir. purposes of illustrating the construction.

In electrical installations and equipment For reinforcin t W and for Other 20 which include Within a confining wall a body of reasons which will appear hereinafter, the upper insulation of a liquid character, for example an and 0f the Cylindrical Wall 3 desirably is Closed oil-filled cable, it is desirable to provide means to with a flang d member 9, the flange around its accommodate for the expansion and contraction ute e e nv ni tl bein We d d to the of the insulating material without permitting pp end of the Wall end mber 9 also 25 ingress of air and moisture, and without the foras a pwa y e i entra y located mation of voids or gas spaces in the insulation. ge 10 defin ng an opening ll throu the To further this end it is desirable that this member 9- Meunted Within the container, b ve means continuously maintain pressure on the inthe e d member is an inverted D p d sulating material. As used herein the expression member comprisin in e u at e bed liquid insulation includes any insulating mament, a cylindrical wall !2 extending downwardterial which in the course of service manifests 1y nto t e annular Space formed w n he characteristics of fluidity. Ordinarily the liquid casing 5 and the cylindrical wall 8, and a flanged insulation will be an oil, and conveniently may end member I3, conveniently welded to the upper be so described. end of the cylindrical wall I2. 35

Referring to Fig. l of the drawing, two cable The inverted cup shaped member is free to lengths 3| are united within a joint casing 32 move vertically within the container, and desirwhich is connected fluid-tight at its ends to the able means are provided for accurately guiding sheaths of the cable lengths, as by means of the cup shaped member in its vertical movement wiped joints. The confined space within the to prevent contact between the wall I2 and the 40 joint casing 32 surrounding the united cable ends casing 5 or the Wall 8, thereby reducing frictional ordinarily is filled with a liquid insulation, usualresistance to movement of the cup shaped memly in direct continuity with the insulation in one her. In the illustrative embodiment this guidor both of the connected cable lengths. ing means comprises a guide rod I4 depending The joint casing 32 is connected by means of from and secured centrally of the end member 45 a pipe 33 and the connector 4 with a variable oa- 13. This guide rod l4 passes downwardly through pacity, fluid-tight container or reservoir conthe opening H in the end member 9 into a guide taining a body of liquid insulation, and having sleeve l5 conveniently secured at its lower end means for exerting pressure on the liquid into the end member 1. Rotation of the cup shaped 5O sulation. In the illustrative embodiment a conmember within the container may be prevented, fined. body of gas under pressure is relied upon if desired, by providing the guide rod M with a for exerting pressure on the liquid insulation, key slot l6 and the guide sleeve 15 with a set and the container comprises a vertically arranged screw II, the inner end of which enters the key cylindrical casing 5 closed at its upper and lower slot I6.

ends, respectively, by the flanged end members It will be apparent from the description thus 55 far that the inverted cup shaped member is free to move vertically within the container, such movement being accurately guided to insure the maximum freedom of movement. As shown in the accompanying drawing, the cup shaped memher is nearly at the lowest point of its vertical movement. Continued downward movement of the cup shaped member will be halted when its end member l3 engages the flange IE on the member 9. By suitably dimensioning the parts, this engagement desirably will occur before the lower end of the cylindrical wall l2 engages the bot tom of the container.

Within the annular space between the container wall 5 and the cylindrical wall 8, and surrounding the depending wall 52 of the inverted cup shaped member is a body 23 of liquid which is heavier than the insulating liquid. This liquid, for example mercury, constitutes a seal between the lower edge of the invert-ed cup shaped member and the container wall 5, and divides the container into two chambers comprising the gas and the liquid insulation compartments. In the illustrative embodiment the upper compartment contains the liquid insulation and the lower compartment contains gas under pressure, but this arrangement may be reversed if desired.

Since the inverted cup shaped member is free to move vertically within the container, the pres sure on the liquid insulation in the upper portion of the container normally will be substantially the same as the pressure on the gas in the lower portion of the container. There being no material difference in these pressures, the mercury or other liquid 23 will function as a seal between the bodies of gas and liquid insulation, normally preventing all contact therebetwcen. As the volume of liquid insulation within the container varies, because of changing conditions of service in the electrical installation, the pressure on the gas within the container will vary, but the pressure on both sides of the inverted cup shaped member will always equalize.

Desirably a valve i8 is provided for the oil outlet pipe which is closed automatically as the inverted cup shaped member approaches the upper limit of its range of movement. This valve prevents passage of the mercury or other sealing liquid and the gaseous pressure medium into the electrical installation or equipment 'in the event that the reservoir is emptied of its liquid insulation.

The valve may be secured to the connector 4 in such a manner that it will be closed as the inverted cup shaped member moves upwardly against it. Or, as shown in Fig. 2, the lower part of the connector 4 may serve as the valve seat, and the valve closure member may be secured on top of the inverted cup shaped member.

Centrally secured on top of the end member I3 is a low spider or yoke 4% Secured on the upwardly spread arms of this spider is a plate 4| which closes the opening to the connector 4 when the inverted cup shaped member is moved to its upper limit. Conveniently a gasket 32 of oil resistant material insures a tight closure. The parts are proportioned so that as the reservoir empties of liquid insulation the valve closes before any of the sealing liquid is forced out of its channel. To take care of any small leak through the Valve 18 some movement of the cup shaped member may be permitted as by the use of a helical spring between it and the valve, or by making the spider 43 of elastic material. Y

When the flow of liquid insulation rvers esthe by pass valve 43, hinged to the plate 4! and normally held in closed position by a spring 44, is forced open by the pressure. This opening of valve 43 permits return of liquid insulation into the reservoir until the pressure is sufiicient to force the inverted cup shaped member downwardly to open the main valve, whereupon the valve 43 again closes.

Ifa valve is not provided to close the outlet to the pipe 33 as the inverted cup shaped member approaches the upper limit of its range of movement, a stop should be provided to prevent the members l3 and 6 being forced directly together. Such a stop functions to halt upward movement of the floating cup shaped member while there still is suflicient space so that if all of the liquid insulation were drained out of the container there would be no chance of the mercury following the oil into the cable or other electrical installation. That is, the residual space between the members l3 and 6 Would be able to retain as much of the mercury as could be forced out of the annular groove by the gas pressure.

Means are provided for supplying liquid in-- sulation to the upper portion of the container, and conveniently this means may take the form of a valved grease plug l9 secured in an opening in the upper end member 6. This grease plug desirably is protected against dirt and moisture by a cap 20.

Gas under pressure conveniently is supplied to the lower portion of the container through a tire valve 2| secured in an opening in the lower end member 1. This valve may be protected against dirt and moisture by a cap 22.

Desirably means are provided for observing the amount of liquid insulation contained within the reservoir at any time. In the illustrative embodiment a window 24 is provided in the casing 5 intermediate its ends. Conveniently this window is provided with a pane 25 of glass held in place by the rim 26. Gaskets are provided at the edge of the glass to prevent breakage and to provide a fluid-tight seal. Pressure on the rim 25 against the glass conveniently is obtained by means such as the screws 28 and the nuts 29.

The mercury which acts as a seal between the liquid insulation and the body of gas is much heavier than the liquid insulation. The level where the insulating liquid and the mercury meet may be readily observed through the glass 25. As the amount of insulating material within the container increases, the mercury level will rise in the glass, and as the volume of insulating material decreases, the mercury level will fall.

This construction lends itself readily to the use of 'an alarm and signal system for giving electrically an indication of the amount of oil within the reservoir. The mercury is itself a conductor, and can be used to complete electrical circuits through contacts mounted in the outer wall of the container at or near the extreme limits of movement in each direction.

A window similar to the window 24, or a gauge glass, notshcwmmay be provided in the bottom of the "reservoir to permit inspection for determining whether any of the liquid insulation has been forced through the mercury seal. Any such liquid may be withdrawn through the valve 2 I.

If the insulating liquid and the sealing liquid are of such natu "es that the latter may dissolve or evaporate slightly into the former, means desirably are provided to remove these traces of sealing liquid from the insulating liquid. Where 7 5 ing a screen or mass 35 of metal for which the mercury has a high affinity. For example, 35 may comprise copper, brass or lead W001.

The reservoir thus far described is comparatively simple and inexpensive to manufacture. Since there are no thin flexible metal diaphragms or tubes such as have been employed heretofore in reservoirs for this type of service, all danger of contact between the insulating liquid and the gaseous pressure medium due to failure of the metal is eliminated.

Furthermore, the construction is comparatively foolproof as regards handling during installation. There is no necessity for supplying the mercury to the reservoir until the reservoir has been mounted in its place of installation, as by means of brackets 39. However, if the mercury is supplied to the reservoir before it has been mounted in its final position, there is practically no danger of permanent displacement of the mercury during the handling of the reservoir.

If the reservoir is tipped sufficiently the seal between the gas and the liquid insulation compartments will be broken. But when the reservoir is again returned to its normal position the mercury will at once fall back into the annular recess between the casing 5 and the wall 8, re-establishing the seal. By reason of the shapes of the members 9 and I3, and the provision of the flange it on the member 9, it is practically impossible for any of the mercury to escape into the bottom of the container.

If during installation or service there should be a sudden surge of pressure on the insulating liquid sufiicient to blow some of the insulating liquid through the mercury seal, the mercury seal would immediately re-establish itself, and such oil blown through the seal would merely float on top of the mercury between the members 9 and R3, or if sufiicient in quantity would flow through the flanged opening ll into the bottom part of the reservoir.

It will be understood that the invention may be variously modified and embodied within the scope of the sub-joined claims.

We claim:

1. The combination with a length of sheathed, oil-filled cable, of means for preserving the integrity of the cable insulation under changing conditions comprising a fluid-tight container, an inverted cup shaped member smaller and of less length than the container within and connected fluid-tight at its open end to the lower end of the container, said cup shaped member having a flanged opening through its closed end, a second inverted cup shaped member within the con- Itainer having its wall extending downwardly into the annular space formed between the first mentioned cup shaped member and the wall of the container, means for supplying gas under pressure to the container on one side of the second mentioned cup shaped member, means for supplying oil to the container on the other side of the second mentioned cup shaped member, means connecting the container with the cable permitting the flow of oil therebetween, and a body of liquid heavier than the oil within the said annular space constituting a seal between the gas and the oil while permitting movement of the second mentioned cup shaped member as the volume of oil within the container varies.

2. The combination with a length of sheathed, oil-filled cable, of means for preserving the integrity of the cable insulation under changing conditions of service comprising a fluid-tight container having formed within its lower part an annular space, an inverted cup shaped member within the container having its wall extending downwardly into the said annular space, means for supplying gas under pressure to the container on the under side of the cup shaped member, means for supplying oil to the container on the upper side of the cup shaped member, means connecting the container with the cable permitting the flow of oil therebetween, and a body of liquid heavier than the oil within the said annular space constituting a seal between the gas and the oil while permitting movement of the cup shaped member as the volume of oil within the container varies.

3. The combination with an electrical installa tion which includes a body of liquid insulation within a confining wall, of means for preserving the integrity of the insulation comprising a vertically disposed, fluid-tight cylindrical container, a cylindrical wall slightly smaller in diameter and of less length than the container within and connected fluid-tight at its lower end to the lower end of the container, a cover secured fluid-tight to the upper end of said cylindrical wall, an inverted cup shaped member within the container having its wall extending downwardly into the annular space formed between the said cylindrical wall and the wall of the container, means for supplying gas under pressure to the container on one side of the cup shaped member, means for supplying liquid insulation to the container on the other side of the cup shaped member, means connecting the container with the said installation permitting the flow of liquid insulation therebetween, and a body of mercury within the said annular space constituting a seal between the gas and the liquid insulation while permitting movement of the cup shaped member as the volume of liquid insulation within the container varies.

4. The combination with an electrical installation which includes a body of liquid insulation within a confining wall, of means for preserving the integrity of the insulation under changing conditions comprising a fluid-tight cylindrical container, a cylindrical wall smaller in diameter and of less length than the container within and connected fluid-tight at one end to the lower end of the container, an inverted cup shaped member within the container having its wall extending downwardly into the annular space formed between the said cylindrical wall and the wall of the container, means for supplying gas under pressure tothe container on one side of the cup shaped member, means for supplying liquid insulation to the container on the other side of the cup shaped member, means connecting the container with the said installation permitting the flow of liquid insulation therebetween, a body of liquid heavier than the liquid insulation within the said annular space constituting a seal between the gas and liquid insulation while permitting movement of the cup shaped member as the volume of liquid insulation within the container varies, and means for preventing flow of the sealing liquid out of the said annular space into the electrical installation under abnormal operating conditions.

5. A variable capacity reservoir for supplying liquid insulation under pressure to an electrical 75 installation comprising, in combination, a fluidtight cylindrical container, a cylindrical wall slightly smaller in diameter and of less length than the container within and connected fluidtight at one end to the lower end of the container, an inverted cup shaped member within the container having its wall extending downwardly into the annular space formed between the said cylindrical wall and the wall of the container, means for supplying gas under pressure to the container on one side of the cup shaped member, means for supplying liquid insulation to the container on the other side of the cupshaped member, a body of mercury within the said annular space constituting a seal between the gas and the liquid insulation while permitting movement of the cup shaped member as the volume of liquid insulation within the container varies, and a window in the wall of the corn tainer permitting observation of the mercury level to indicate the volume of liquid insulation within the container.

6. The combination with a length of sheathed, oil-filled cable, of means for preserving the integrity of the cable insulation under changing conditions of service comprising a fluid-tight container having formed within its lower part an annular space, an inverted cup shaped member within the container having its wall extending downwardly into the said annular space, means for supplying gas under pressure to the container on one side of the cup shaped member, means for supplying oil to the container on the other side of the cup shaped member, means connecting the container with the cable permitting the flow of oil therebetween, a body of liquid heavier than the oil within the said annular space constituting a seal between the gas and the oil while permitting movement of the cup shaped member as the volume of oil within the container varies, valve means for controlling the flow of oil between the container and the cable, and means for closing said valve automatically when the quantity of oil within the container reaches a predetermined minimum.

'7. The combination with a length of sheathed,

oil-filled cable, of means for preserving the in-* tegrity of the cable insulation under changing conditions of service comprising a fluid-tight container having formed within its lower part an annular space, an inverted cup shaped member within the container having its wall extending downwardly into the said annular space, means for supplying gas under pressure to the container on one side of the cup shaped member, means for supplying oil to the container on the other side of the cup shaped member, means connecting the container with the cable permitting the flow of oil therebetween, a body of liquid heavier than the oil within the said annular space constituting a seal between the gas and the oil while permitting movement of the cup shaped member as the volume of oil within the container varies, and means associated with said annular space for causing the sealing liquid to return to the annular space and re-establish the seal following any surge of pressure which temporarily may have broken the seal.

8. The combination with a length of sheathed, oil-filled cable, of means for preserving the integrity of the cable insulation under changing conditions of service comprising a fluid-tight container having formed within its lower part an annular space, an inverted cup shaped member within the container having its wall extending downwardly into the said annular space, means for supplying gas under pressure to the container on one side of the cup shaped member, means for supplying oil to the container on the other side of the cup shaped member, means connecting the container with the cable permitting the flow of oil therebetween; a body of liquid heavier than the oil within the said annular space constituting a seal between the gas and the oil while permitting movement of the cup shaped member as the volume of oil within the container varies, and filter means in the connection between the container and the cable for removing from the oil any of the sealing liquid which may have been dissolved in the oil.

RALPH W. ATKINSON. ALBERT M. HAGEN.

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