US2070974A - Electric cable system and joint therefor - Google Patents

Description

Feb. 16, 1937. F. c. MEYER ELECTRIC CABLE SYSTEM AND JOINT THEREFOR Filed April 27, 1934 J INVEN TOR.

Mhfmww A TTORNE YS.

Patented Feb. 16, 1937 UNITED STATES PATENT OFFICE ELECTRIC CABLE SYSTEM AND JOINT THEREFOR Jersey Application April 27, 1934, Serial No. 722,655

6 Claims.

` This invention is directed to an improvement in semi-stop joints which are particularly adapted for use in cable systems wherein a plurality of insulated but unsheathed cable conductors are enclosed in a pipe line lled with oil under pressure which may be as high as two hundred and fifty pounds or even higher, the pipe line being of large internal diameter to permit of relative movement of the insulated conductors so that shaking of the conductors can take place without detrimeutally affecting the installation.

One of the objects of the invention is the provision of a semi-stop joint construction in which the necessity for piping exterior to the joint is eliminated.

Another object of the invention is the provision of means for'separating or isolating the oil in sections of the pipe line.

A` further object of` the invention is the provision of a joint which permits of drawing the oil from any section of the line desired, for the purpose of repairs, inspection, renewals, etc., without the necessity of draining the oil from any other section.

A still further object ofthe invention is the provision of a construction in which the joint structure is such as to provide a stiffener structure between the pipe lines which are united by the joint. v

A still further object of the invention is the provision of a joint construction whichpermits of pipe expansion and contraction due to thermal conditions. v

In the accompanying drawing:

IFig. l is a longitudinal sectional view of a joint constructed in accordance with the invention, the section being taken on the line I-I of Fig. 2;

Fig. 2 is a cross section of the joint of Fig. 1 taken on the line 2-2 of said iigure; and

Fig. 3 is a longitudinal View of a modiiied joint.

Referring to the drawing in detail and first of all to the embodiment illustrated in Figs. 1 and 2, A and B designate the adjacent ends of the cable pipe line in which the cable is to be installed. This pipe line which may be of any suitable material, metal fiber, etc. capable of holding pressure, is of relatively large internal diameter so that the cable conductors can be readily drawn thereinto and so that relative movement will be permitted' between the several insulated conductors composing the cable thereby providing for snaking of the cable conductors when the cable is placed in service.

The ends of the pipe lines are provided with increasers I and 2 bellied at thiil inner ends a5 ample, wrapped about the conductor.` In addi- 10 l tion to the insulation 6 each conductor is provided With electrostatic shielding tape I, such as a thin copper tape wrapped spirally about the insulation.

In practice the cable conductors madeup as 15 above described are enclosed in a temporary lead sheath for shipment to the installation. In drawing the cable conductors into the pipe line the temporary lead sheath is removed as will be brought out hereinafter. l 20 8 designates the enclosing casing of the joint within which the cable conductors are to be joined.

Within the joint casing 8 adjacent each end thereof are barrier plates II of non-magnetic material such as bronze extending transversely of the casing and bolted rigidly to the upset ends of the increasers I and 2 by bolts I2. Each of these barrier plates is provided with thimbles I3 for receiving thefcable conductors, the bore in 30 each of the thimbles being slightly tapered as shown.

In making up the joint a wrapping I4, surgical webbing, for instance, or any non-magnetic material either fibrous or metallic, is applied imme- 35 diately about the short sheath length 9 which is left about each conductor, the 'remainder of each temporary lead sheath being removed as the conductors are drawn into the pipe line. This wrapping is applied spirally about the lead with a half 40 lap and the conductor so prepared is jammed into the tapered thimbles of the barrier plates II, thus providing a wedge type seal holding-the Wrapping in its proper position and thus reinforcing the sheath at this point. l 4'5 The sheath lengths 9 oier high resistance to oil flow from one side of the barrier plates to the other. The length of these sections depends on the pressure used and requirements to be met, but in any event it will be appreciated that the 50 longer the lengths the more eiective they are in reducing oil ow.

The ends of the cable conductors are brought together and joined as shown at I5 intermediate i the barrier plates I I and then wrapped with varnished cambric and paper tape I8. Finally cop-y per braid I1 is wrapped about the varnisbed cambric and paper tape and each end soldered to the wipe joints I8 which connect the ends of the short sheath lengths 9 and thimbles I3.

When the wrapping I4 is of brous material it is terminated short of the forward end of each 4casing 8 into the cable and from thence to the pipe line, there being only a slight seepage through the insulation and strands of the conductor.

As thus far described it will be appreciatedl that lengths of sheath 9 Just long enough to wipe to the thimbles I3 would be eilective as a stop feature and any additional length of these sleeves reduces the oil ow, the greater the length the less the oiliiow. A condition might arise, however, where there is an oil iiow from the joint casing through the cable insulation and the conductor strands to the pipe line, in which event a tensional stress is set up in the sheath lengths or sleeves 9, likely to cause rupture particularly close to the barrier plates. This condition is taken care of in the present construction by the wrapping Il.

The enclosing casing 8 of the joint overlaps the ends of the-increasers I and 2. The iointcasingfl 28, the increasers I and 2 and the end of ther enclosing joint casing 8. lBolts 22 serve to draw up the rings 28 to provide a liquid tight joint between the joint casing and the pipefincreasers 'me cable pipe .une is kept snee with ou 24'l under suiiiciently high pressure to increase the l dielectric strength of the oil, for example, iron-i ilve atmospheres upwards and inasmuch as com-l munication is desired betweenA the interior of the y joint casing 8 and the cable ypipe line, while avoidng piping exterior to the joint, I provide, at each end of the joint a valve-controlled pipe 23. These pipes lie wholly within vthe joint casing and pipe line. The valves controlling these pipes may be hand operated or automatic and will be closed either manually or automatically in the event of a leak in the system.

It'will be seen from the foregoing that this structure eliminates the necessity of external piping for maintaining` communication .between y the following advantages.

joint and the section of pipe line containing the cable to which access is desired. The joint casing 8 could then be slipped to one side, the barrier plate thus exposed removed and the cable withdrawn and another section pulled in without disturbing any of the rest of the line at all.' So that here I have a joint for buried in -the ground" cable systems which necessitates merely W190i'- ering a joint for the purpose of obtaining access toa cable section, thus avoiding the trouble and expense of uncovering an entire length of cable which has been necessary heretofore withk buried in the ground cable systms. If manholes are erected with this type of construction not only do I obtain the advantages of present day conduit constructions but the advantages of a buried in the ground system.

While I have described a construction in which the sheathed lengths 9 have been left on the cable at the barrier plates I I, it is to be understood that if desired packing glands may be substituted for these sheath lengths.

l In the embodiment of my invention illustrated in Fig. 3 I provide barrier plates II, eachv equipped with thimbles I3 for receiving the cable conductors. The increasers I and 2 of Fig. l are done away with, and instead of securing the barrier'plates to these increasers, I provide the barrier plateswith a large diameter sleeve-like rearward extension Il', these extensions being telescoped by the joint casing 8. The extensions II' where they project from the joint casing are `materially reduced in diameter to provide offset or eccentric sleeves 25 of the same diameter as the pipe lines and in alignment therewith. These eccentric sleeves or extensions terminate short y of the ends of the pipe line to leave a gap 26.

Each of the eccentric sleeves 25 of the barrier plates is provided with a ring-21 and surrounding the adjacent end of the pipe line lengths to be joined is a ring 28. Between these two rings 21 and 28 and surrounding the eccentric sleeve 25 of the barrier plates as well as the cable pipe line is a sleeve 28. Lead tipped gaskets 30 are interposed between the ends of the sleeve 28 and the rings 21 and 28 and the sleeve-like extension 28 of the barrier plate and cable pipe line.

Bolts 3| connect the rings 21 and 28, and when these bolts are drawn up a liquid-tight joint is providedbetween the ends of the extension oi' the-barriei'plates and the cable pipe line. 'Ihis traction of the pipe line dueto thermal condidesignates a loose ring similar to the ring 28 of Fig. 1 surrounding each barrier plate extension A lead tipped gasket 34 is interposed between the ring 33, the end ofthe joint casing 8 and the extension II' of the barrier plate so that when vthe bolts 35 connecting the rings 32 and 33 are set up a liquid tight joint is provided between the end of the joint casing and the bar--A rier plate. By providingthe large diameter extensions or sleeves II it will be appreciated enough friction will be provided to prevent detrimental relative movement between 4the barrier plates and joint casing,l and by providing the reduced diameter sleeves 25 which terminate short'of the pipe line movement'ofV the pipe line is permitted without transmitting this movement to the joint.

To maintain communication between the in# terior of the joint casing 8 ,and of the cable pipe line and yet eliminate the necessity of external piping, I provide a valve 36 in each /of the barrier plates Il, the valve stems lying within the sleeves Il', the valve stems projecting from the offset between the sleeves il' and 25 so as to be accessible for adjustment if desired or necessary. These valves 36 may be flow operated or otherwise automatically operated if desired.

It will be understood that the cable conductors in this embodiment of my invention may be joined in the same manner as in Fig. 1 and that the thimbles I3 in the barrier plates will be wiped to the short sheath lengths 9.

In this embodiment of my invention, therefore, I have eliminated all external piping, provided for stiffening the joint so that the barrier plates Il will remain at a fixed distance apart, and at the same time provided for a certain amount of movement of the pipe line relatively to the joint, due to settling and thermal conditions without transmitting such movement to a detrimental extent to the joint.

What I claim is:-

1. In combination a joint casing for high tension electric cable systems, a barrier plate within said jointy casing adjacent each end thereof, a pipe line filled with oil maintained under high pressure, insulated cable conductors in said pipe line, means for rigidly connecting said barrier plates to the adjacent ends of two lengths of the pipe line, thimbles for said barrier plates for receiving said cable conductors, the cable conductors extending through said thimbles into the interior of the joint casing, means for joining the ends of the conductors within said joint casing, each of said cable conductors being provided with a short length of an impervious metal sheath surrounding the insulation of the conduc- 40 tor and extending through said thimbles, a nonmetallic wrapping about that portion of each impervious metal sheath which extends through a thimble, a wiped joint uniting veach of said thimbles with the metal sheath of the conductor passing through that thimble, oil under high pressure filling the cable pipe line and oil under the same pressure filling the joint casing.

2. In combination a joint casing, barrier plates within the joint casing adjacent each end thereof, a cable pipe line, said barrier plates being sealed to said pipe line, insulated cable conductors in said pipe line, means for connecting each end of the joint casing to the cable pipe line liquid tight, thimbles for said barrier plates, each of said conductors being provided with a short length of lead sheath about the insulation thereof, a non-magnetic material about the, short length of lead sheath of each conductor, the lead sheathed portion of each conductor extending through a thimble of said barrier plates into the interior of said joint casing, means for joining the adjacent ends of the conductors within said joint casing, a wiped joint for uniting each thimble with the lead sheath of its conductor, oil under high pressure filling the pipe line and oil under the same pressure iilling the said joint casing, and anenclosed valve controlled pipe extending from the pipe line through each of said barrier plates and terminating within the joint casing to maintain communication between the interior of the joint casing and of said cable pipe line.

3. In combination a joint casing, barrier plates within the joint casing adjacent each end thereof, a cable pipe line, insulated cable conductors in said pipe line, means for connecting each end of the joint casing to the cable pipe line liquid tight, thimbles for said barrier plates, each of said conductors being provided with a short length of lead sheath about the insulation thereof, a fibrous 'material about the short length of lead sheath oi' each conductor, the lead sheathed portion of each conductor extending through a thimble of said barrier plates into the interior of said joint casing the fibrous material extending into the thimble and terminating short of the forward end thereof, means for joining the adjacent ends of the conductors within said joint casing, a wiped joint for uniting each thimble with the lead sheath of its conductor, oil under high pressure filling the pipe line and oil under the same pressure filling the said joint casing, and an enclosed valve controlled pipe extending from the pipe line through each of said barrier plates and terminating within the joint casing to maintain communication between .the interior of the joint casing and of said cable pipe line.

4. A joint for high tension electric cable systems of the type in which the insulated cable conductors are laid in a pipe line of sufilciently large diameter to permit of free relative movement of the insulated conductors, the pipe being filled with oil maintained under high pressure, said joint comprising in combination an enclosing joint casing within which the conductors are to be joined, a barrier within the joint casing at each end thereof, and rigidly attached to the ends of adjacent pipe sections and overlapped by the joint casing, thimbles integral with said barriers, each of said thimbles having a tapered bore, an insulated cable conductor passing through each of said thimbles to the interior of the joint casing for joining within the casing, that portion of each conductor passing through said thimbles being provided about its insulation with a short length of lead sheath and with fabric wrapped about said sheath, insulation about the joint of the cable conductors, a metal covering about the `last mentioned insulation, said metal covering, the lead sheath and said thimbles being connected by wipe joints, a ange adjacent each end of the joint casing and rigid therewith, a ring loosely surrounding each of said pipe sections, packing between the said rings, the pipe sections and the ends of the joint casing, and bolts connecting said fianges and rings whereby a liquid-tight joint is provided between each end of the joint casing and the cable pipe, oil filling the joint casing and a valve controlled pipe at each end of the joint lying within the pipe line and passing through said barrier plates and terminating within the joint casing, whereby the oil within the joint casing is maintained at the same high pressure as the oil within the pipe line.

5. A joint for high tension electric cable systems of the type in which the insulated cable conductors are laid in a pipe line of sufiiciently large diameter to permit of free relative movement of the insulated conductors, the pipe line being filled with oil under high pressure, said joint comprising in combination an enclosing joint casing, barrier plates within the casing adjacent the'ends thereof, means for rigidly connecting the barrier plates to the ends of the pipe line, and a pipe passing through the barrier plates and enclosed by the joint casing and pipe line and terminating within the casing for maintaining communication between the joint casing and pipe line.

6. Inl combination a pipe line nlled with oil maintained under high pressure, a joint in the pipe line,y said joint comprising a joint casing the ends of whichrare secured liquid-tight to the pipe line, barrierlvpiates within the joint casing secured to the ends oi the pipe line.

stiiening members within said joint casing secured to said barrier plates and extending from` vthe barrier plates at one end oi' the casing to the barrier plates yat the opposite end of the casing, insulated cable conductors passing liquidtight through said barrier plates and spliced to each other within said casing, and valve -controlled pipes terminating within the joint casing for maintaining communication between the pipe line and the interior of the joint asing whereby the joint casing is kept filled with oil at the same pressure as the oil in the pipe line.

FREDC. MEYER.

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