US1969721A - Cable system - Google Patents

Description

Aug 14, 1934. c E, BENNETT CABLE SYSTEM File-d. Dec. 21. 1952 I I IiZVENTOR.

Patented Aug. 14, 1934 UNITED STATES PATENT OFFICE CABLE SYSTEM corporated, Paterson, New Jersey N. J., a corporation of Application December 21, 1932, Serial No. 648,161

3 Claims.

This invention is directed to animprovement in electric cable systems, and is a further devel opment of the pressure cable system constituting the subject matter of my copending application Serial No. 553,714, filed July 29, 1931.

One of the objects of the present invention is the provision of a cable system in which the insulated conductors of the cable are enclosed in fibre, steel, iron, lead or other suitable material capable of withstanding high internal pressures, the pipe or sheath being sufliciently large internally to provide a reservoir for oil or other insulating liquid under pressure about the insulated cable conductor. As set out in my copending application above referred to, the volume of the insulating liquid and the pressure are such as to improve the thermal properties of the system, substantially increase the dielectric strength of the insulating liquid and to insure that the insulation of the cable conductors will be maintained thoroughly impregnated with insulating liquid thereby improving the operation of the cable and increasing its carrying capacity. So far as pressure is concerned I have found that best results are obtained when operating at pressures not substantially less than five atmospheres.

In the drawing accompanying this application:

Fig. 1 is a more or less diagrammatic view of a cable system constructed in accordance with the present invention; and

Fig. 2 is an enlarged view of a part 01. the system 01' Fig. 1.

Referring to the drawing in detail, 1 designates a tubular casing such as pipe or steel, iron, fibre, lead or other suitable material of sufficient strength to withstand the internal pressures to which it is to be subjected in practice, this pipe or sheath being buried in the ground and extending from end to end of the system. It will be understood that this pipe or sheath will be of suflicient internal diameter or of such internal construction as to provide a reservoir for a substantial volume of oil or other fluid insulating liquid about and in contact with the insulation of the cable conductors. At intervals the sheath or pipe 1 is provided with semi-stop joints 2.

At each end of the system, that is, at each end of the pipe or sheath 1, I provide pressure supply tanks 3 communicating with the pipe or sheath and containing fluid insulating material such as oil 4, an inert gas such as nitrogen being provid 6. over the top of the oil and maintained un er pressure to hold the oil in the system at the desired pressure. It may be necessary owing to'the length oi the system to provide tanks similar to the tanks 3 intermediate the ends of the system and such a tank has been shown at 6.

The conductors of the cable are terminated in potheads 7 and 8, passing out of the pipe or sheath 00 through manifold outlet pipes 9. This construction in detail constitutes the subject matter of another copending application and hence will not be described in further detail. At each end of each joint 2 I provide a by-pass pipe 10 equipped with an automatic valve 11, the purpose of this construction being to prevent drainage of the entire system in the event of a leak in the pipe or sheath 1. The valves 11 are of such construction that should a leak occur in the pipe or sheath 1 that section of the pipe or sheath in which the break or leak has occurred will be isolated automatically from the rest of the system. This structure is also the subject matter of a copending application and hence will not be described in further detail.

It may be desirable, as for example in the event of a break in the, system, to be able to drain any pipe or sheath section between joints 2, and to this end I provide a pipe 12 paralleling the system and connected thereto by valve controlled pipes 13, each of which as will be seen is equipped with a shut-off valve 14. By closing the proper valves 14 it will be appreciated that any section of the system between shut-off valves may be isolated and drained without necessitating drainage of the rest of the system, thereby permitting of the repair or replacement of any part of the system at the minimum of expense.

What I claim is:-.

1. An electric cable system comprising in combination a tubular casing enclosing the insulated conductors of the cable, supply tanks at each end of the system communicating with the interior of said tubular casing for supplying fluid insu- 95 lating material to the interior of said tubular casing, an inert gas under pressure in said tanks for maintaining the fluid insulating material in the tubular casing of the system at a minimum pressure of substantially five atmospheres, ter- 100 minals for the system communicating with the interior of said tubular casing, semi-stop-joints at intervals along the cable system, by-pass pipes connecting each end of said joints with the adjacent cable length, and an automatic valve in each 105 of said pipes operable in the event of a leak in the system to isolate the leaking section or the tubular casing from the remainder of the system, thereby preventing accidental draining of the system.

2. An electric cable system comprising in combination a tubular casingfor the insulated conductors of the cable, a supply tank at each end of the system and communicating with the interior of said tubular casing for supplying fluid insulat lng material thereto at a pressure not substantially less than five atmospheres, a terminal for each end of each conductor, each of said terminals communicating with the interior of said tubular casing, an inert gas in each of said tanks for maintaining the fluid insulating medium throughout the system at a pressure oi not substantially less than five atmospheres, joints at intervals in said system, a by-pass pipe at each end of each joint connecting the same with the tubular casing adjacent thereto, an automatically operable valve in each by-pass pipe, said valves operating in the event oi! a leak in said system to isolate the leaking length from the remainder of the system, a drain pipe paralleling the tubular casing, and valve controlled connections between said drain pipe and the tubular casing to permit of draining predetermined lengths or sections of the tubular casing independently of the remainder of the tubular casing.

3. An electric cable system comprising in combination a tubular casing, an insulated cable conductor within said casing, said conductor being freely movable within said casing, means for maintaining said casing filled with liquid insulating material under pressure in which the conductor and its insulation are submerged, automatic valves operable in the event of a leak in the system to isolate the leaking section of the casing from the remainder of the system, a normally empty drain pipe paralleling the said casing, and valve controlled connections from the casing to the said drain pipe to permit of draining and isolating the leaking section of the said casing independently of the oil supply means and of the remainder of the system.

CHARLES E. BENNETT.

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