US1968019A

US1968019A - Electric cable

Info

Publication number: US1968019A
Application number: US648897A
Authority: US
Inventors: Charles E Bennett
Original assignee: Okonite Callender Cable Co Inc
Current assignee: Okonite Callender Cable Co Inc
Priority date: 1932-12-27
Filing date: 1932-12-27
Publication date: 1934-07-31
Anticipated expiration: 1951-07-31

Description

July 31, 1934. Q El BENNETT 41,968,019

ELECTRIC CABLE Filed Dec. 27, 1952 4, will ATTORNEYS.

Patented Jury 31, 1934 AUNITED sTATEsQPArr-:Nr opp-'ICE 1,968,019v `v 4 ELECTRIC CABLEy Charles E. Bennett, Hawthorne, N. J., assignor to The Okonite-Callender Cable Company, Incorporated, Paterson, N. J., a -corporation of New Jersey Application necember'l'zr. 1932, serial No. 648,897

conductors are maintained submerged in an in-v sulating uid such as oil which is constantly maintained under high pressure.

li In thesystem of the present applicationI propose to provide a sealed enclosure filledwith oil i or other insulating fluid and in which the insulated conductor is submerged, the' present invention providing for permitting the casing or enclosure to expand under temperature rises and to return to its original size when temperature returns to normal to provide a breathing action, thereby toinsure that the insulation of the oonductor or conductors will be maintained lled with insulating fluid at all times and that voids and gas pockets in the insulation will be avoided. In the accompanying drawing in which I have shown several embodiments of my invention:

Fig. 1 is across section `of one embodiment of the invention;

Fig. 2 is a similar view of a modification; 'and Fig. 3 is a similar view -of still another embodiment of the invention.

Referring to the drawing in detail and rstmf all to Fig. 1, my vimproved 'cable which for purposes of illustration has been shown as a three conductor cable, comprises

conductors

1, 2 and 3, insulated by oil impregnated paper, for example, 4. The insulated conductors'are drawn into'a tubular casing, pipe or enclosure 5 of ferrous metal, such as steel, for instance, of the necessary wall thickness to withstand whatever pressures it may be desired to operate at but at the same time of sulllcient elasticity to permit of the desired movement under pressure increase. I have shown an oval pipe for purposes of illustration but it will be understood that the pipe -5 may take other forms, the intent being to provide a pipe capable of being distorted under high pres,- sure and of returning to initial condition when the pressure drops( The pipe 5 is iilled with oil or other insulating .fluid 6 in which the linsulated conductors 1, 2 a'nd 3 are submerged.

If 'an initial pressure is applied to the insulating fluid it'willy be of ,the vorder mentioned in l1 Claims. (Cl. 247-3) my copending, application above referred to, say for example, ve atmospheres minimum up to several hundred pounds maximum, such pres- -1 sures being suliiciently high to increase the dielectric strength of the oil. w

As understood by those skilled in this art the operation of high tension cables causes the insulating uid of the cable to expand in volume, the

lfluid returning to its original volume during the coolingcycle. I 4wish to avail myself of these 65 changes in volume of the fluid insulating medium of the cable. Consequently I construct the pipe 5k of steel or other elastic material capable of being expanded by the pressures built up in the insulating uid on the heating cycle and of re- 'I0 A turning to its initial or normal shape on the cooling cycle. Employing apipe such as illustrated in the drawing it 'will be seen that when 'the fluid 6 in which the conductors are submerged heats up to increase its volume, the increase in pressure which results will expand the pipe 5 from the full line position to the dotted line position of Fig. 1.-

On the cooling cycle the pipe will contract or return to its original shape due to the elasticity A of the material of which it is constructed, thereby to provide a pulsating or breathing action tending to prevent the formation of voids or gas pockets in the insulation of the cable and insuring very desirable working conditions" at all. times. Furthermore, if the oil Sis maintained under a pressure of the order above referred to, then it will be understood that not only will the breathing action above referred to be morel pronounced but .I am assured of the benet of 90 an increase in the ldielectric strengthof the oil resulting from the high pressure employed. In the embodiment of my invention illustratedV v in Fig. 2 I employ the same type. of construction as just described. except that I partially nll the tubular casing or pipe 5 with a filler 7 of coarse sand, stone, or any other suitable freely movable solid material which does not pack readily so as not to destroy vor'interfere with the desired direct contact of the body of insulating uid 6 with 100 the exterior of the insulating envelope 4 of each conductor. The filler 7 reduces the volume of insulating fluid 6 necessary to ll the pipel 5, without sacrificing the area of the radiating surface of the pipe. The filler 7, particularly where sand is employed, for example, may be mixed with the insulating uid 6 and the two materials introduced together into the casing 5, the sand particles, as will be understood, settling to the bottom of the casing.

In the embodimentoi' my invention as illustrated in Fig. 3 I have shown a pipe 5, and insulated conductors l, 2 and 3, this pipe being oval shaped, as distinguished from round, but instead of making the Wall of the pipe elastic it may be rigid, the purpose-of this construction being to provide a very extensive heat radiating surface and a relatively small amount of oil as compared 'with a round pipe having the` same radiating surface.

It is to be understood ofcourse that in this embodiment of my invention having the insulating fluid initially at atmospheric pressure, or

jinitially under pressures, such ras above mensufllcient to increase the dielectric4 other than oval may be employed Within the purtrical energy, said system comprising in combination a conductor, oil impregnated insulation for the conductor, an all elastic metal non-circular tubular casing loosely enclosing the conductor and its insulation, liquid insulation in said casing and in which the conductor and its rinsulation are submerged, said enclosing casing expanding toward circular cross section by the building up of pressure in the casing due to heating of theliquid insulation on the heating cycle of the cable, to increase the capacity of the casing, the casing contracting to its original capacity on the cooling cycle.

2. A cable system of the oil filled type for the underground transmission of high tension electrical energy, said system comprising in combination a conductor, oil impregnated insulation for the conductor, an all elastic metal noncircular tubular casing of uniform Awall thickness loosely enclosing the conductor and its insulation,` liquid insulation in said casing and in which the conductor and its insulation are submerged, said enclosing casing expanding towards circular cross section by the building up of pressure in the casing due to heating of the liquid insulation on the heating cycle of the cable, to lincrease the capacity of the casing, the

ycasing contracting to its original capacity on the cooling cycle. y f

3. A cable system of the oil lled type for the underground transmission of high tension electrical energy, said system comprising in combination a'plurality of unsheathed cable conductors of the solid stranded type, oil impregnated insulation foreach of said conductors, an all elastic metal non-circular tubular casing loosely enclosing said conductors and their insulation, liquid insulation in said casing and in which the conductors and their insulation are submerged, said enclosing casing expanding toward circular cross section by the building up of pressure in the casing due to heating of the liquid insulation on the heating cycle of the cable, to increase the capacity of the casing, the casing contracting to its original capacity on the cooling cycle.

4. A cable system of the oil lled type for the underground transmission of high tension electrical energy, said system comprising in combination a 4plurality of unsheathed cable conductors of the solid stranded type, oil impregnated insulation foreach of said conductors, an all elastic metal non-circular tubular casing loosely enclosing said conductors and their insulation, liquid insulation in said casing and in which the conductors and their insulation are submerged, means for maintaining said liquid insulation under pressure, said enclosing casing expanding toward circular cross section by the building up of pressure in the casing due to heating of the liquid insulation on the heating cycle of the cable, to increase the capacity of the casing, the casing contracting to its original capacity on the cooling cycle.

5. A cable system of the oil iilled type for the underground transmission of high tension electrical energy, said system comprising in'combination a plurality of unsheathed cable conductors of Vthe solid stranded type, oil impregnated in sulation for each of said conductors, an all elastic metal non-circular tubular casing loosely enclosing said conductors and their insulation,'liquid insulation in said casing and in which the conductors and their insulation are submerged, means for maintaining said liquid insulation under suiiiciently high pressure to increase its dielectric strength, said enclosing casing expanding toward circular cross section by the building up vof pressure in the casing due to heating of the liquid insulation on the heating cycle of the cable, to increase the capacity of the casing, thel casing contracting to its original capacity on the cooling cycle.

6; A cable system of the oil lled type for the underground transmission of high tension electrical energy, said system comprising in combi-` and their insulation, a loosely packed freely movable solid material Within said` casing for reducing the capacity thereof, and liquid insulation filling the space in said casing unoccupied by the insulated conductors and said loosely packed solid material, said conductors and their insulation being submerged in said liquid insulation and loosely packed solid material, said enclosing casing expanding toward circular cross section by the building up of pressure in the casing due to heating of the liquid insulation on the heating cycle of the cable, to increase the capacity of the casing, the casing contracting to its original capacity on the cooling cycle.

7. In the installation of multi-conductor high tension electric cable systems the method which i a.. In the instauacionfof multi-conductor high tension electric cable systems the method which comprises drawing a plurality of unsheathedy conductors each provided with permeable insulation into a pipe line and lling the spaces in the'y pipe line unoccupied bythe conductors and their insulation with oil and a loosely packed freely movable solid material so that the conductors and their insulation are at all times submerged in said oil and loosely packed material, and placing the oil under a pressure not substantially less than ve atmospheres to increase its dielectric strength.

9. A multi-conductor high tension electric cable system comprising in combination a plurality of unsheathed cable conductors each conductor being independently insulated with permeable impregnated insulating material, a pipe line enclosing said conductors, the internal diameter of said pipe line relatively to the space occupied by the conductors and their insulation being such as to permit of said insulated conductors being drawn into the pipe line, oil and a loosely packed freely movable solid material filling the space unoccupied by said conductors and their insulation and in' which the conductors and their insulation are submerged and in which the insulated conductors have free movement relatively to each other, and means for maintaining said oil under sufficiently high pressure to increase its dielectric strength.

10. A multi-conductor high tension electric cable system comprising in-ccmbination a plurality of unsheathed cable conductors of the solid stranded type each conductor being independently insulated with permeable impregnated insulating material, a pipe line enclosing said conductors, the internal diameter ot said pipe line relatively to the space occupied by the conductors and their insulation being such as to permit of said insulated conductors being drawn into the pipe line, oil and a loosely packedfreely movable solid material illling the. space unoccupied by said conductors and their insulation and in which the conductors and their insulation are submerged and in which the insulated conductors have free movement relatively to each other, and means for maintaining said oil under a pressure of not' substantially less than ve atmospheres to increase its dielectric strength.

ll. A multi-conductor high tension electric cable system comprising in combination a plurality of unsheathed cable conductors of the solid stranded type each conductor being independently insulated with permeable impregnated insulating material, a pipe line of elastic metal enclosing said conductors, said' pipe line being sutilciently elastic to permit it to change its capacity in accordance with variations in the volume of the liquid insulation by reason of thermal changes in the system, the internal diameter o! said pipe line relatively to the space occupied by the conductors and their insulation being such as to permit oi' said insulated conductors beingdrawn into the pipe line, oil and 'a loosely packed freely movable solid material iilling the space unoccupiedl by said conductors and their insulation and in which the conductors and their insulation are submerged and in which the insulated conductors have free movement relatively to each other, and means for maintaining said oil under a pressure of not substantially less than five atmospheres to increase its dielectric strength.

CHARLES E. amm.